ABS pulsation felt in brake pedal
05-21-2014, 08:45 AM
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ABS pulsation felt in brake pedal
Now that my new battery has arrived, I will pull a fresh set of codes, so I can start troubleshooting the ABS and traction control lights. I hope it is just cold solder joints in the relay, but am prepared to go the course.
I was out on a test drive a couple of days ago. I didn't do anything wild. just trying to get used to driving the new toy. The ABS light was on the whole time, except when I stopped for a light. I felt a 1 second pulsation in the pedal, and I noticed the light went off. It stayed off the rest of the way back home. When I restarted the engine several hours later, it was back on.
I'm just wondering what this means as far as to help me diagnose the problem. Is this the symptom of the cold solder joints in the ABS relay, or a bad ground?
I was out on a test drive a couple of days ago. I didn't do anything wild. just trying to get used to driving the new toy. The ABS light was on the whole time, except when I stopped for a light. I felt a 1 second pulsation in the pedal, and I noticed the light went off. It stayed off the rest of the way back home. When I restarted the engine several hours later, it was back on.
I'm just wondering what this means as far as to help me diagnose the problem. Is this the symptom of the cold solder joints in the ABS relay, or a bad ground?
05-21-2014, 12:07 PM
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Need to know the codes. There are dozens of different codes that can set the ABS light.
Taking a stab the light on and then going off would seem like an intermittant electrical problem. Loose or poor connection, bad solder joint, failing sensor.... Question is which component(s) of the ABS system are experiencing the issue. EBCM? Wheel Speed Sensors? Steering wheel Position Sensor? Yaw sensor?????? Codes tell you. Without codes you STAB in the dark.
Taking a stab the light on and then going off would seem like an intermittant electrical problem. Loose or poor connection, bad solder joint, failing sensor.... Question is which component(s) of the ABS system are experiencing the issue. EBCM? Wheel Speed Sensors? Steering wheel Position Sensor? Yaw sensor?????? Codes tell you. Without codes you STAB in the dark.
05-21-2014, 06:27 PM
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Update on the new codes:
P1571 H C ASR Desired Torque
TCS No Communication
SDM U1040 H C Loss of Communications with TCS
Did some digging, and found this about the grounds:
G101 provides the ground for the BPMV and is located on the left frame rail in front of the windshield washer reservoir.
G108 provides the EBCM ground and it is located in the forward lamp harness, below the battery tray on the frame rail (CKT 1251).
G106 is the PCM ground is which is located in the engine harness, RH side of the engine, above the starter (CKT 451).
I'm thinking this is a good place to start. Any comments welcomed...
Here is the section dealing with the P1571 code:
________________________________________ _____________________________
P1571
One of the following conditions exists:
The PCM detects that requested torque signal is out of the valid range.
The PCM does not receive the requested torque signal.
Action Taken When the DTC Sets
If equipped, the following actions occur:
The EBCM disables the TCS/VSES for the duration of the ignition cycle.
The PCM will store conditions which were present when the DTC set as Fail Records data only.
The Traction Control and Active Handling indicator turns ON.
The DIC displays the following messages:
Service Traction System
Service Active Handling
The ABS remains functional.
Conditions for Clearing the DTC
The condition for the DTC is no longer present (the DTC is not current) and you used the scan tool Clear DTC function.
The condition for the DTC is no longer present (the DTC is not current) and you used the On-Board Diagnostics Clear DTC function.
The EBCM automatically clears the history DTC when a current DTC is not detected in 100 consecutive drive cycles.
The PCM automatically clears the history DTC when a current DTC is not detected in 40 consecutive warm-up cycles.
Diagnostic Aids
The following conditions can cause this concern:
An open in the requested torque circuit
An short to ground or voltage in the requested torque circuit
A wiring problem, terminal corrosion, or poor connection in the requested torque circuit
A communication frequency problem
A communication duty cycle problem
The PCM is not receiving information from the EBCM
Loose or corroded EBCM ground or PCM ground
A DTC P1571 may set along with several other PCM DTCs if the key is held in the CRANK position while the engine is running. The starter lockout function of the PCM is enabled several seconds after the engine is running and prevents the starter from engaging while the engine is running. This will cause a partial loss of power to some components and systems.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
Clear the DTC in order to verify that the fault is present.
Measure the requested torque signal in order to determine if the signal has a valid duty cycle.
Measure the requested torque signal in order to determine if the signal has a valid frequency.
This vehicle is equipped with a PCM which uses an electrically erasable programmable read only memory (EEPROM). When replacing the PCM, the replacement PCM must be programmed.
Step
Action
Values
Yes
No
Schematic Reference: ABS Schematics
Connector End View Reference: ABS Connector End Views or Powertrain Control Module (PCM) Connector End Views in Engine Controls-5.7 L
1
Did you perform the ABS Diagnostic System Check?
--
Go to Step 2
Go to Diagnostic System Check - ABS
2
Inspect the EBCM ground and PCM ground, making sure each ground is clean and torqued to the proper specification. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?
--
Go to Step 13
Go to Step 3
3
Install a scan tool.
Turn ON the ignition, with the engine OFF.
Use the scan tool in order to clear the DTCs in both the EBCM and PCM.
Turn OFF the ignition.
Start the engine.
Does the DTC reset as a current DTC?
--
Go to Step 4
Go to Testing for Intermittent and Poor Connections in Wiring Systems
4
Turn OFF the ignition.
Disconnect the EBCM harness connector.
Install the J 39700 universal breakout box using the J 39700-300 cable adapter to the EBCM harness connector and the EBCM connector.
Start the engine.
Measure the DC duty cycle between the requested torque signal circuit and a good ground.
Is the duty cycle within the specified range?
5-95%
Go to Step 5
Go to Step 6
5
Measure the DC Hz between the requested torque signal circuit and a good ground.
Does the frequency measure within the specified range?
121-134 Hz
Go to Step 8
Go to Step 6
6
Turn OFF the ignition.
Disconnect the J 39700-300 cable adapter from the EBCM connector.
Important
Disconnecting the EBCM connector and turning ON the ignition could cause other modules to set loss of communication DTCs (Uxxxx). Once the EBCM is reconnected, the EBCM may set DTC C1298.
Turn ON the ignition, with the engine OFF.
Measure the voltage from the requested torque signal circuit to a good ground.
Does the voltage measure within the specified range?
4-6 V
Go to Step 10
Go to Step 7
7
Turn OFF the ignition.
Disconnect the powertrain control module (PCM) harness connector.
Test the requested torque signal circuit for the following conditions:
A short to voltage
A short to ground
Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?
--
Go to Step 13
Go to Step 10
8
Turn OFF the ignition.
Disconnect the powertrain control module (PCM) harness connector.
Test the requested torque signal circuit for the following conditions:
An open
A high resistance
Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?
--
Go to Step 13
Go to Step 9
9
Inspect for poor connections the harness connector of the PCM. Refer to Testing for Intermittent and Poor Connections and Connector Repairs in Wiring Systems.
Did you find and correct the condition?
--
Go to Step 13
Go to Step 11
10
Inspect for poor connections the harness connector of the EBCM. Refer to Testing for Intermittent and Poor Connections and Connector Repairs in Wiring Systems.
Did you find and correct the condition?
--
Go to Step 13
Go to Step 12
11
Important
The replacement PCM must be programmed.
Replace the PCM. Refer to Powertrain Control Module (PCM) Replacement in Engine Controls - 5.7 L.
Did you complete the repair?
--
Go to Step 13
--
12
Replace the EBCM. Refer to Electronic Brake Control Module (EBCM) Replacement .
Did you complete the repair?
--
Go to Step 13
--
13
Use the scan tool in order to clear the DTCs.
Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.
Does the DTC reset?
--
Go to Step 2
System OK
--------------------------------------------------------------------------------
Document ID# 684616
2002 Chevrolet Corvette
P1571 H C ASR Desired Torque
TCS No Communication
SDM U1040 H C Loss of Communications with TCS
Did some digging, and found this about the grounds:
G101 provides the ground for the BPMV and is located on the left frame rail in front of the windshield washer reservoir.
G108 provides the EBCM ground and it is located in the forward lamp harness, below the battery tray on the frame rail (CKT 1251).
G106 is the PCM ground is which is located in the engine harness, RH side of the engine, above the starter (CKT 451).
I'm thinking this is a good place to start. Any comments welcomed...
Here is the section dealing with the P1571 code:
________________________________________ _____________________________
P1571
One of the following conditions exists:
The PCM detects that requested torque signal is out of the valid range.
The PCM does not receive the requested torque signal.
Action Taken When the DTC Sets
If equipped, the following actions occur:
The EBCM disables the TCS/VSES for the duration of the ignition cycle.
The PCM will store conditions which were present when the DTC set as Fail Records data only.
The Traction Control and Active Handling indicator turns ON.
The DIC displays the following messages:
Service Traction System
Service Active Handling
The ABS remains functional.
Conditions for Clearing the DTC
The condition for the DTC is no longer present (the DTC is not current) and you used the scan tool Clear DTC function.
The condition for the DTC is no longer present (the DTC is not current) and you used the On-Board Diagnostics Clear DTC function.
The EBCM automatically clears the history DTC when a current DTC is not detected in 100 consecutive drive cycles.
The PCM automatically clears the history DTC when a current DTC is not detected in 40 consecutive warm-up cycles.
Diagnostic Aids
The following conditions can cause this concern:
An open in the requested torque circuit
An short to ground or voltage in the requested torque circuit
A wiring problem, terminal corrosion, or poor connection in the requested torque circuit
A communication frequency problem
A communication duty cycle problem
The PCM is not receiving information from the EBCM
Loose or corroded EBCM ground or PCM ground
A DTC P1571 may set along with several other PCM DTCs if the key is held in the CRANK position while the engine is running. The starter lockout function of the PCM is enabled several seconds after the engine is running and prevents the starter from engaging while the engine is running. This will cause a partial loss of power to some components and systems.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
Clear the DTC in order to verify that the fault is present.
Measure the requested torque signal in order to determine if the signal has a valid duty cycle.
Measure the requested torque signal in order to determine if the signal has a valid frequency.
This vehicle is equipped with a PCM which uses an electrically erasable programmable read only memory (EEPROM). When replacing the PCM, the replacement PCM must be programmed.
Step
Action
Values
Yes
No
Schematic Reference: ABS Schematics
Connector End View Reference: ABS Connector End Views or Powertrain Control Module (PCM) Connector End Views in Engine Controls-5.7 L
1
Did you perform the ABS Diagnostic System Check?
--
Go to Step 2
Go to Diagnostic System Check - ABS
2
Inspect the EBCM ground and PCM ground, making sure each ground is clean and torqued to the proper specification. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?
--
Go to Step 13
Go to Step 3
3
Install a scan tool.
Turn ON the ignition, with the engine OFF.
Use the scan tool in order to clear the DTCs in both the EBCM and PCM.
Turn OFF the ignition.
Start the engine.
Does the DTC reset as a current DTC?
--
Go to Step 4
Go to Testing for Intermittent and Poor Connections in Wiring Systems
4
Turn OFF the ignition.
Disconnect the EBCM harness connector.
Install the J 39700 universal breakout box using the J 39700-300 cable adapter to the EBCM harness connector and the EBCM connector.
Start the engine.
Measure the DC duty cycle between the requested torque signal circuit and a good ground.
Is the duty cycle within the specified range?
5-95%
Go to Step 5
Go to Step 6
5
Measure the DC Hz between the requested torque signal circuit and a good ground.
Does the frequency measure within the specified range?
121-134 Hz
Go to Step 8
Go to Step 6
6
Turn OFF the ignition.
Disconnect the J 39700-300 cable adapter from the EBCM connector.
Important
Disconnecting the EBCM connector and turning ON the ignition could cause other modules to set loss of communication DTCs (Uxxxx). Once the EBCM is reconnected, the EBCM may set DTC C1298.
Turn ON the ignition, with the engine OFF.
Measure the voltage from the requested torque signal circuit to a good ground.
Does the voltage measure within the specified range?
4-6 V
Go to Step 10
Go to Step 7
7
Turn OFF the ignition.
Disconnect the powertrain control module (PCM) harness connector.
Test the requested torque signal circuit for the following conditions:
A short to voltage
A short to ground
Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?
--
Go to Step 13
Go to Step 10
8
Turn OFF the ignition.
Disconnect the powertrain control module (PCM) harness connector.
Test the requested torque signal circuit for the following conditions:
An open
A high resistance
Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?
--
Go to Step 13
Go to Step 9
9
Inspect for poor connections the harness connector of the PCM. Refer to Testing for Intermittent and Poor Connections and Connector Repairs in Wiring Systems.
Did you find and correct the condition?
--
Go to Step 13
Go to Step 11
10
Inspect for poor connections the harness connector of the EBCM. Refer to Testing for Intermittent and Poor Connections and Connector Repairs in Wiring Systems.
Did you find and correct the condition?
--
Go to Step 13
Go to Step 12
11
Important
The replacement PCM must be programmed.
Replace the PCM. Refer to Powertrain Control Module (PCM) Replacement in Engine Controls - 5.7 L.
Did you complete the repair?
--
Go to Step 13
--
12
Replace the EBCM. Refer to Electronic Brake Control Module (EBCM) Replacement .
Did you complete the repair?
--
Go to Step 13
--
13
Use the scan tool in order to clear the DTCs.
Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.
Does the DTC reset?
--
Go to Step 2
System OK
--------------------------------------------------------------------------------
Document ID# 684616
2002 Chevrolet Corvette
Last edited by Biotex; 05-21-2014 at 06:59 PM.
05-22-2014, 07:38 AM
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P1571 H C ASR Desired Torque
TCS No Communication
SDM U1040 H C Loss of Communications with TCS
Were these 3 the only codes that you have or were there others????
Did you have any other symptoms when driving the car other than ABS light coming on/going off on the dash??
Any TCS codes such as C1214
TCS No Communication
SDM U1040 H C Loss of Communications with TCS
Were these 3 the only codes that you have or were there others????
Did you have any other symptoms when driving the car other than ABS light coming on/going off on the dash??
Any TCS codes such as C1214
You think I should put some more miles on the car before trying to solve this one?
Last edited by Biotex; 05-22-2014 at 07:42 AM.
05-22-2014, 12:36 PM
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The ABS light is staying on because of the P1571. That is USUALLY accompanied with a C1276 of C1277 under TCS.
Us the TCS No Communications under the
10 - PCM sensor????
I would clear all codes and do some normal driving to see if there are other codes that will come up.
Double check battery cable connections to insure they are clean and tight.
There may be a ground issue that needs to be addressed.
I can't remember if you had battery acid under the battery tray on the PCM wiring or not. Did you check that when you had the battery out??
Us the TCS No Communications under the
10 - PCM sensor????
I would clear all codes and do some normal driving to see if there are other codes that will come up.
Double check battery cable connections to insure they are clean and tight.
There may be a ground issue that needs to be addressed.
I can't remember if you had battery acid under the battery tray on the PCM wiring or not. Did you check that when you had the battery out??
Battery connections are clean and tight.
BTW, the No Comm code was listed under TCS, not PCM.
I drove it to work today, so will see if any new codes pop up.
Edit: Just pulled codes again. Nothing new. Still got the 28 TCS No Comm, the P1571 and the U1040
Also, was doing some searching and came across this thread wher this guy has the exact same 3 codes.
http://forums.corvetteforum.com/c5-t...on-lights.html
In my situation, the PO replaced the belt tensioner pulleys (or something that was squeaking) on the front of the engine. Wonder if this is related...
Anyway, I verified the two maxi fuses were not blown. They both checked good visualy.
Last edited by Biotex; 05-22-2014 at 01:12 PM.
05-22-2014, 04:44 PM
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I did check fuse #5 earlier today. It was fine. I will do those voltage checks when i get home. That will eliminate some guess work. One thing I'm going to do, is document this step by step and post the final resolution. I have found several other posts that left us hanging as to the fix. 
Wanted to add that I took the car to lunch for the first time. I can't handle the stress of possible door dings
Good news was no new codes popped up.
Thanks for the link and diagrams. I put them all together into a word document, and printed it out. I do have Alldata on my mome computer, but it is a lot lacking compared to the FSM. I wish the digital ones were readily available on the cheap.
Wanted to add that I took the car to lunch for the first time. I can't handle the stress of possible door dings
Good news was no new codes popped up.
Thanks for the link and diagrams. I put them all together into a word document, and printed it out. I do have Alldata on my mome computer, but it is a lot lacking compared to the FSM. I wish the digital ones were readily available on the cheap.
Last edited by Biotex; 05-22-2014 at 04:47 PM.
05-22-2014, 09:26 PM
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I did the fuse check under the hood, and read proper battery voltage on all of the fuses indicated in the ignition switch check above.
Under Hood Fuse Center fuses I checked, Good meaning full battery voltage was present on both sides of the fuse, measured on top of the fuses with them plugged in.
ENG ING1 FUSE# 19 Good
INJR 2 FUSE# 18Good
THROTCONT FUSE# 17Good
INJR 1 FUSE# 22Good
PCM FUSE# 16Good
F/PMP FUSE# 13Good
More to come...
Under Hood Fuse Center fuses I checked, Good meaning full battery voltage was present on both sides of the fuse, measured on top of the fuses with them plugged in.
ENG ING1 FUSE# 19 Good
INJR 2 FUSE# 18Good
THROTCONT FUSE# 17Good
INJR 1 FUSE# 22Good
PCM FUSE# 16Good
F/PMP FUSE# 13Good
More to come...
Last edited by Biotex; 05-23-2014 at 08:08 PM.
05-23-2014, 08:12 PM
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Ok, so I checked the voltage to the I/P as follows:
Instrument Panel Fuse block:
BTSI BU Fuse# 21Good
BCM 13 Fuse# 22Missing fuse
IPC Fuse# 19 Good
Fuse #22 is missing, and it doesn't show as supposed to being there according to the diagram on the inside cover of the panel. I did measure battery voltage on one side of the fuse holder, so if there was a fuse in the socket, whatever it powers would get voltage.
Anyone know what this BCM 13 Fuse# 22 powers? On image #3 above, the schematic shows a 10A fuse, but the wire kind of terminates. Any ideas?
I removed the electric plug going to the EBCM, and inspected the pins. Everything looks to be clean and free of any obvious defects. I was kind of amazed at how easily the plug removed from the connector. I made sure to plug it back in as snugly as possible. I put the safety pin back in the place it is supposed to go, as it was hanging loose when I found it.
Still looking for the EBCM ground so I can check it out. All comments welcome as I'm not real sure where to go from here next.
Edit: Did a google search, and found this old thread. It explains that fuse 22 doesn't power anything as I suspected:
http://forums.corvetteforum.com/c5-t...e-removed.html
Ok, so what's next? I've ruled out the ignition switch causing low voltage.
Instrument Panel Fuse block:
BTSI BU Fuse# 21Good
BCM 13 Fuse# 22Missing fuse
IPC Fuse# 19 Good
Fuse #22 is missing, and it doesn't show as supposed to being there according to the diagram on the inside cover of the panel. I did measure battery voltage on one side of the fuse holder, so if there was a fuse in the socket, whatever it powers would get voltage.
Anyone know what this BCM 13 Fuse# 22 powers? On image #3 above, the schematic shows a 10A fuse, but the wire kind of terminates. Any ideas?
I removed the electric plug going to the EBCM, and inspected the pins. Everything looks to be clean and free of any obvious defects. I was kind of amazed at how easily the plug removed from the connector. I made sure to plug it back in as snugly as possible. I put the safety pin back in the place it is supposed to go, as it was hanging loose when I found it.
Still looking for the EBCM ground so I can check it out. All comments welcome as I'm not real sure where to go from here next.
Edit: Did a google search, and found this old thread. It explains that fuse 22 doesn't power anything as I suspected:
http://forums.corvetteforum.com/c5-t...e-removed.html
Ok, so what's next? I've ruled out the ignition switch causing low voltage.
Last edited by Biotex; 05-23-2014 at 08:28 PM.
05-24-2014, 06:11 PM
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New information that may help to narrow down my issue. I went for a 200 mile drive today. After about 15 miles, the ABS light went off. Stayed off for about 20 miles, then the road got rougher, and it came back on and stayed on. To me it seemed to coincide with the bumps in the road making it come on.
The computer was flashing Service ABS, Service Active handling, Service Tire pressure system etc...
I suppose there will be some new codes for me to pull, but this new info might help, so I'd love to hear your thoughts.
The computer was flashing Service ABS, Service Active handling, Service Tire pressure system etc...
I suppose there will be some new codes for me to pull, but this new info might help, so I'd love to hear your thoughts.
05-25-2014, 08:17 AM
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05-25-2014, 09:30 AM
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Just finished cleaning the two grounds behind the headlights. Reset the codes, and immediately got these back.
10-PCM 1571 H
28-TCS NO COMM
40-B0502 H C
B0507 H C
B2482 H C
58-SDM U1040 H C
Not knowing where to begin, I'm going to try looking at the PCM connections since they are relatively easy to get to. I don't think it is a ground issue. The grounds I took apart were like new. Zero corrosion.
10-PCM 1571 H
28-TCS NO COMM
40-B0502 H C
B0507 H C
B2482 H C
58-SDM U1040 H C
Not knowing where to begin, I'm going to try looking at the PCM connections since they are relatively easy to get to. I don't think it is a ground issue. The grounds I took apart were like new. Zero corrosion.
05-25-2014, 10:57 AM
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What voltage are you seeing on the gauge?
I noticed that when my alternator went crazy (due to a bad connection), the charging volts went up to 15.4 V. When that happened I got several ABS messages. The solution was the clean the field wire on the alternator and spray it with de-ox-it.
Charging voltage dropped back down to 13.4V and no more ABS messages.
Maybe not your problem, but worth checking.
I noticed that when my alternator went crazy (due to a bad connection), the charging volts went up to 15.4 V. When that happened I got several ABS messages. The solution was the clean the field wire on the alternator and spray it with de-ox-it.
Charging voltage dropped back down to 13.4V and no more ABS messages.
Maybe not your problem, but worth checking.
05-25-2014, 11:36 AM
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What voltage are you seeing on the gauge?
I noticed that when my alternator went crazy (due to a bad connection), the charging volts went up to 15.4 V. When that happened I got several ABS messages. The solution was the clean the field wire on the alternator and spray it with de-ox-it.
Charging voltage dropped back down to 13.4V and no more ABS messages.
Maybe not your problem, but worth checking.
I noticed that when my alternator went crazy (due to a bad connection), the charging volts went up to 15.4 V. When that happened I got several ABS messages. The solution was the clean the field wire on the alternator and spray it with de-ox-it.
Charging voltage dropped back down to 13.4V and no more ABS messages.
Maybe not your problem, but worth checking.
05-25-2014, 11:43 AM
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PCM connections were secure and clean. I decided to remove the EBCM and have a look at the solder joints. It is now apart on my desk. I'm looking it over, but I'm not seeing anything obvious. Might send it out for repair.
05-25-2014, 12:52 PM
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The only repair that anyone does on the EBCM is the main power relay. It can either fail or if it has cold or cracked solder joints it will give an intermittent C1214.
Here is a thread about a DIY repair if you have NOT already seen it:
http://forums.corvetteforum.com/c5-t...r-fleabay.html
I suspect that you have already looked up the new codes but perhaps not. The B0502 and B0507 are the left and right driving light relay circuits (38 and 40 in the passenger foot well fuse box)
B2482 is the backup lamp relay circuit (38 in the under hood fuse box)
Have you looked at the BCM metal box in the passenger foot well??? Does it have any white oxidation stains on it??
Here is a thread about a DIY repair if you have NOT already seen it:
http://forums.corvetteforum.com/c5-t...r-fleabay.html
I suspect that you have already looked up the new codes but perhaps not. The B0502 and B0507 are the left and right driving light relay circuits (38 and 40 in the passenger foot well fuse box)
B2482 is the backup lamp relay circuit (38 in the under hood fuse box)
Have you looked at the BCM metal box in the passenger foot well??? Does it have any white oxidation stains on it??
I'll look into the BCM, shortly. The solder joints in the last photo are after I repaired them.
05-25-2014, 02:22 PM
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Pulled and inspected the BCM. No evidence of moisture. It looks to be as it was when new.
After all of todays work, I'm still in the same boat. Same codes!
At this point, I'd like to know what can cause the 28-TCS NO Comm condition? My gut tells me this is the key to most of it...
After all of todays work, I'm still in the same boat. Same codes!
At this point, I'd like to know what can cause the 28-TCS NO Comm condition? My gut tells me this is the key to most of it...
05-25-2014, 04:34 PM
#17
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CI 6,7,8,9,11 Vet
St. Jude Donor '08
That nesty stain on the EBTCM Board could be part of the problem...
You stated that you were seeing other weird DTCs. Could be caused by a corrupted serial data buss.
Next to the BCM are two thin connectors. Find the one wity FOUR wires and pop the shorting cap off the top of the connector and see if you gain comms with the EBTCM
BC
You stated that you were seeing other weird DTCs. Could be caused by a corrupted serial data buss.
Next to the BCM are two thin connectors. Find the one wity FOUR wires and pop the shorting cap off the top of the connector and see if you gain comms with the EBTCM
BC
05-26-2014, 08:36 AM
#18
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Removed Star Connector #2. Cleared all codes. Started engine, shut down, read codes.
Got all the same codes as before, but added a couple more NO COMM's.
AO-LDCM
A1-RDCM
A6-SCM
I put the connector back in, used my pick to make sure all four wires were inserted all the way from the back side of the connector. The three no comm's above went away. Still getting the 28-TCS NO COMM
Got all the same codes as before, but added a couple more NO COMM's.
AO-LDCM
A1-RDCM
A6-SCM
I put the connector back in, used my pick to make sure all four wires were inserted all the way from the back side of the connector. The three no comm's above went away. Still getting the 28-TCS NO COMM
Last edited by Biotex; 05-26-2014 at 08:54 AM.
05-26-2014, 08:45 AM
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CI 6,7,8,9,11 Vet
St. Jude Donor '08
Its NOT a serial data buss issue...
05-26-2014, 08:51 AM
#20
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CI 6,7,8,9,11 Vet
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You should have gotten THREE No COMMS codes LDCM, RDCM and SCM.
Thats what modules connect to that STAR connector and feed thru to the other STAR connector.
Thats what modules connect to that STAR connector and feed thru to the other STAR connector.