C1243 DC current measurements
10-14-2008, 05:52 PM
#1
Instructor
Thread Starter
C1243 DC current measurements
I have a 98 with rear mounted EBCM/BMTV and just finished the exercise routine (thanks Bill Curlee) that has been referenced in earlier posts. Since mine was rear mounted I chose to use a battery charger as a 12 volt source and since I am a retired electrical engineer I added a DC current meter into the circuit to see what was really the condition voltage and current wise with a stuck motor and what happens afterward.
I used a fairly large wire to keep it from heating and used a spade lug to plug into pin 8.
I used the 10 amp setting on my VOM as it was the highest scale I had I also used the leads from the amp meter as a switch to apply the voltage to the motor.
Results: The initial meter reading was greater than 10 amps and the voltage from the battery charger dropped to under 10 volts. The motor ran but was indeed slow.
I continued to run it in short bursts and eventually the current came down to 5 amps and the voltage stayed at 12+ volts.
Here is a video of the final run. You can hear the motor run. It will take
55 seconds to down load with high speed.
Observations: I am a retired IBMer and based on my experience with analog and digital circuits I think what happens when C1243 is posted: the computer has sensed that the current going to the motor is higher than a predetermined setting and assumes the motor is stuck. A DC motor will draw high current when the armature is not turning and the result is the voltage drops. I think for this type of repair it is probably better to use a battery charger rather than your battery as you want to start with a lower inital current until the armature starts turning at speed. This will save the internal circuit in the BTMV (they are called land patterns) and keeps from heating the wire. If you monitor the curernt and it drops to 5 to 6 amps ( you can read this on the battery charger) then you are done.
If you want more information send me a PM.
I used a fairly large wire to keep it from heating and used a spade lug to plug into pin 8.
I used the 10 amp setting on my VOM as it was the highest scale I had I also used the leads from the amp meter as a switch to apply the voltage to the motor.
Results: The initial meter reading was greater than 10 amps and the voltage from the battery charger dropped to under 10 volts. The motor ran but was indeed slow.
I continued to run it in short bursts and eventually the current came down to 5 amps and the voltage stayed at 12+ volts.
Here is a video of the final run. You can hear the motor run. It will take
55 seconds to down load with high speed.
Observations: I am a retired IBMer and based on my experience with analog and digital circuits I think what happens when C1243 is posted: the computer has sensed that the current going to the motor is higher than a predetermined setting and assumes the motor is stuck. A DC motor will draw high current when the armature is not turning and the result is the voltage drops. I think for this type of repair it is probably better to use a battery charger rather than your battery as you want to start with a lower inital current until the armature starts turning at speed. This will save the internal circuit in the BTMV (they are called land patterns) and keeps from heating the wire. If you monitor the curernt and it drops to 5 to 6 amps ( you can read this on the battery charger) then you are done.
If you want more information send me a PM.
The following users liked this post:
Ortegb01 (12-04-2022)
10-14-2008, 07:06 PM
#2
Tech Contributor
Member Since: Dec 1999
Location: Anthony TX
Posts: 32,736
Received 2,180 Likes
on
1,583 Posts
CI 6,7,8,9,11 Vet
St. Jude Donor '08
EXCELLENT WORK and well thought out repair and explanation of the process!!
Now excercize that EBTCS more frequently!
Bill C
Now excercize that EBTCS more frequently!
Bill C
The following users liked this post:
Ortegb01 (12-04-2022)
10-16-2008, 11:01 AM
#4
Instructor
Thread Starter
The repair was successfully tested! Today I exercised the ABS with a hard stop from 40 miles per hour ( don't try this in the city) and the 'ABS Active' message appeared momentarily indicating it had worked as designed. Thanks to forum members that posted their experiences with this problem. Stan
10-16-2008, 11:36 AM
#5
Safety Car
It will be interesting to see the longevity of this repair. I also have the same issue on my 2000. There have been other posts where the pump was exercised and if I remember correctly, it was a short term fix. Your test is unique in that you monitored both the voltage and current to determine when the motor was sufficiently exercised! Great post! Could you keep us posted? Or, I may just PM you at a later date. Thanks again for the great post.
10-16-2008, 12:51 PM
#6
Instructor
Thread Starter
Yes, I will follow up with this thread. I too am wondering what is going on in the BPMV and if it will last. The mileage is 81K and the previous owner never exercised the ABS. Thanks for compliment! Stan
10-21-2008, 12:03 AM
#8
Tech Contributor
Member Since: Dec 1999
Location: Anthony TX
Posts: 32,736
Received 2,180 Likes
on
1,583 Posts
CI 6,7,8,9,11 Vet
St. Jude Donor '08
Once the streets are WET, its a cinch! Wet streets also cause less wear and tear on the tires and suspension. I exercize mine every chance that I get wet or not!
10-21-2008, 12:15 AM
#9
Tech Contributor
I have a 98 with rear mounted EBCM/BMTV and just finished the exercise routine (thanks Bill Curlee) that has been referenced in earlier posts. Since mine was rear mounted I chose to use a battery charger as a 12 volt source and since I am a retired electrical engineer I added a DC current meter into the circuit to see what was really the condition voltage and current wise with a stuck motor and what happens afterward.
I used a fairly large wire to keep it from heating and used a spade lug to plug into pin 8.
I used the 10 amp setting on my VOM as it was the highest scale I had I also used the leads from the amp meter as a switch to apply the voltage to the motor.
Results: The initial meter reading was greater than 10 amps and the voltage from the battery charger dropped to under 10 volts. The motor ran but was indeed slow.
I continued to run it in short bursts and eventually the current came down to 5 amps and the voltage stayed at 12+ volts.
Here is a video of the final run. You can hear the motor run. It will take
55 seconds to down load with high speed.
Observations: I am a retired IBMer and based on my experience with analog and digital circuits I think what happens when C1243 is posted: the computer has sensed that the current going to the motor is higher than a predetermined setting and assumes the motor is stuck. A DC motor will draw high current when the armature is not turning and the result is the voltage drops. I think for this type of repair it is probably better to use a battery charger rather than your battery as you want to start with a lower inital current until the armature starts turning at speed. This will save the internal circuit in the BTMV (they are called land patterns) and keeps from heating the wire. If you monitor the curernt and it drops to 5 to 6 amps ( you can read this on the battery charger) then you are done.
If you want more information send me a PM.
I used a fairly large wire to keep it from heating and used a spade lug to plug into pin 8.
I used the 10 amp setting on my VOM as it was the highest scale I had I also used the leads from the amp meter as a switch to apply the voltage to the motor.
Results: The initial meter reading was greater than 10 amps and the voltage from the battery charger dropped to under 10 volts. The motor ran but was indeed slow.
I continued to run it in short bursts and eventually the current came down to 5 amps and the voltage stayed at 12+ volts.
Here is a video of the final run. You can hear the motor run. It will take
55 seconds to down load with high speed.
Observations: I am a retired IBMer and based on my experience with analog and digital circuits I think what happens when C1243 is posted: the computer has sensed that the current going to the motor is higher than a predetermined setting and assumes the motor is stuck. A DC motor will draw high current when the armature is not turning and the result is the voltage drops. I think for this type of repair it is probably better to use a battery charger rather than your battery as you want to start with a lower inital current until the armature starts turning at speed. This will save the internal circuit in the BTMV (they are called land patterns) and keeps from heating the wire. If you monitor the curernt and it drops to 5 to 6 amps ( you can read this on the battery charger) then you are done.
If you want more information send me a PM.
10-21-2008, 06:40 AM
#10
Tech Contributor
Member Since: Dec 1999
Location: Anthony TX
Posts: 32,736
Received 2,180 Likes
on
1,583 Posts
CI 6,7,8,9,11 Vet
St. Jude Donor '08
I also have a Simpson 260, and I have a PSM-4 {That was the predecessor to the Simpson}.
I also still use them every once in a while.I wont go into the Vacuum Tube voltmeter that I have that still works.
10-21-2008, 12:44 PM
#11
Tech Contributor
man, an AN/PSM-4...I have not seen one of those since I was in tech school at Chanute AFB! Good memories!
12-03-2008, 10:47 AM
#13
Safety Car
Thanks for the update That's what I've been waiting the hear! I now know what my next project is over the winter. 
That's what I've been waiting the hear! I now know what my next project is over the winter.
01-10-2009, 05:51 PM
#14
Burning Brakes
Stan, I had the intermittant C1243 on my 2000, so I did the same thing you did, and got the same results. I installed a 7.5 amp fuse in the line to start out, and it blew immediatly. Next size I had was a 15, and it held up fine. Motor took approx 10 amps initially, but after a series of 2-3 second bursts, it cleaned up, sped up, and dropped to 5-6 amps.
So far , so good.
BIG ISSUE - my 2000 has the ABS unit in the front, and it is REALLY hard to get to. I'm gonna research around and see if there is any way to tie into the motor relay line, and then just fire the motor occasionally when required. I'll start a new thread and see if anyone knows a trick. Here in Texas, we don't get much rain, and I try to not drive in it, so opportunities for "field testing" without ripping the tires off are pretty slim.
DG
So far , so good.
BIG ISSUE - my 2000 has the ABS unit in the front, and it is REALLY hard to get to. I'm gonna research around and see if there is any way to tie into the motor relay line, and then just fire the motor occasionally when required. I'll start a new thread and see if anyone knows a trick. Here in Texas, we don't get much rain, and I try to not drive in it, so opportunities for "field testing" without ripping the tires off are pretty slim.
DG
01-10-2009, 06:42 PM
#15
Melting Slicks
now this is awesome! I think that's the same code I get when my EBCTM acts up. Bill posted some good instructions for me to test the ground and such but I haven't found the time to work on it. when I do I think I will do this also, can you post a link to the other thread which gives details of how you hooked everything up to make the connections? mine's a 99 and will also be hard to reach, but I'll make an attempt. I've been just living with the problem for a long time.
01-11-2009, 11:36 AM
#16
Burning Brakes
McGilles, hooking it up is really easy, after you get the two modules separated. That part is straightforward, just hard to get to everything.
(hint, remove the alternator, and maybe the radiator hose).
First, check the resistance of the ground wire to the frame (it sticks right out of the left side of the module. Mine was pretty grubby, but it still read 0.1 Ohms.
If that is okay, then proceed to remove the electronic (right side) of the ABS unit. 4 torx screws, and a sneaky 5th one (it's the post under the rubber shock absorber in the middle bottom).
After the electronic module half is off, find socket # 8 on the hydraulic module, they are numbered, it's the first one in the 2nd group of sockets, bigger than the others.
You want to get 12 V to that #8 socket. Just look at the spade pin in the electronic unit that plugs into socket #8, and find/make a spade wiring connector that is about the same size. Then just hook a 3-ft wire up, with a 10-15 amp fuse to be safe.
As stated earlier, I used a battery charger with an amp meter, hooked the gnd to the negative battery post on the car, and struck the positive against the wire I fabricated.
The motor will run, probably slow, or it might blow the fuse if it's really slow. just keep contacting it for a couple seconds at a time until it loosens up a bit. Then make a few 10 second passes. It should speed up and run free. I probably did about 10 10-second runs with a cooldown between each, and she was really running nice.
Pretty simple really, just hard to get it apart.
cheers,
DG
(hint, remove the alternator, and maybe the radiator hose).
First, check the resistance of the ground wire to the frame (it sticks right out of the left side of the module. Mine was pretty grubby, but it still read 0.1 Ohms.
If that is okay, then proceed to remove the electronic (right side) of the ABS unit. 4 torx screws, and a sneaky 5th one (it's the post under the rubber shock absorber in the middle bottom).
After the electronic module half is off, find socket # 8 on the hydraulic module, they are numbered, it's the first one in the 2nd group of sockets, bigger than the others.
You want to get 12 V to that #8 socket. Just look at the spade pin in the electronic unit that plugs into socket #8, and find/make a spade wiring connector that is about the same size. Then just hook a 3-ft wire up, with a 10-15 amp fuse to be safe.
As stated earlier, I used a battery charger with an amp meter, hooked the gnd to the negative battery post on the car, and struck the positive against the wire I fabricated.
The motor will run, probably slow, or it might blow the fuse if it's really slow. just keep contacting it for a couple seconds at a time until it loosens up a bit. Then make a few 10 second passes. It should speed up and run free. I probably did about 10 10-second runs with a cooldown between each, and she was really running nice.
Pretty simple really, just hard to get it apart.
cheers,
DG
01-13-2009, 07:14 PM
#17
Instructor
Thread Starter
My repair continues to work...no codes. Test today. I agree with 'The Wrench' in using a battery charger to power this repair. I hesitate to suggest anyone use their battery as a source for safety reasons.
