Has anyone been able to eliminate their CCM?
08-01-2005, 04:00 PM
#1
Safety Car
Thread Starter
Has anyone been able to eliminate their CCM?
Lots of you know my woes with the electronics in my '93. For those that don't, I've completely gutted the interior and electronics of the car and have been having problems with the security system keeping the car from running.
It's currently a liveable problem, but I am having an intermittant stall condition that happens the first time I drive the car after sitting for a day or two. It seems to go away after I reset everything and let the car sit for a few minutes. Unfortunately this tends to happen my first session on the track...not safe. I have tried letting the car idle for awhile, but it doesn't occur until I take it out on the road.
Has anyone successfully eliminated their body computer (CCM) from the early LT-1 cars? All of the security is in that module, so I can't figure out how to remove it. The ECM PROM's I've looked into which claim to eliminate the VATS system only seem to answer the pass-key part, which I've long removed by bridging the inputs with the equivilant resistor.
This winter I'll remove the entire harness and computer and replace with aftermarket, but to do that now would make me miss too many track days.
Anyone have an interim solution?
It's currently a liveable problem, but I am having an intermittant stall condition that happens the first time I drive the car after sitting for a day or two. It seems to go away after I reset everything and let the car sit for a few minutes. Unfortunately this tends to happen my first session on the track...not safe. I have tried letting the car idle for awhile, but it doesn't occur until I take it out on the road.
Has anyone successfully eliminated their body computer (CCM) from the early LT-1 cars? All of the security is in that module, so I can't figure out how to remove it. The ECM PROM's I've looked into which claim to eliminate the VATS system only seem to answer the pass-key part, which I've long removed by bridging the inputs with the equivilant resistor.
This winter I'll remove the entire harness and computer and replace with aftermarket, but to do that now would make me miss too many track days.
Anyone have an interim solution?
08-01-2005, 04:03 PM
#2
Team Owner
The CCM does security and acts as a traffic cop between the ECM, the EBCM and the various dash bits (AC, stereo gauges).
I would think, if you don't care about ABS, getting rid of it should be easy... just upgrade to an LT1 ECM from an Fbody. I think that's the fix...
I would think, if you don't care about ABS, getting rid of it should be easy... just upgrade to an LT1 ECM from an Fbody. I think that's the fix...
08-01-2005, 05:30 PM
#3
Safety Car
Thread Starter
The ECM I have is the same part number called out for an F-body as well...16159278.
There are a couple of security inputs to the CCM (under the dash), but which line communicates to the ECM (under the hood)to tell it to cut off the fuel once it's running? That's the line I need to fool so the ECM thinks life is grand.
There are a couple of security inputs to the CCM (under the dash), but which line communicates to the ECM (under the hood)to tell it to cut off the fuel once it's running? That's the line I need to fool so the ECM thinks life is grand.
08-01-2005, 05:44 PM
#4
Team Owner
hm... I don't suppose you have the Helm Manual???
It might be able to direct you on the harness... and at the very least how to stop it from messing up your day.
It might be able to direct you on the harness... and at the very least how to stop it from messing up your day.
08-01-2005, 05:57 PM
#5
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Originally Posted by ScaryFast
Lots of you know my woes with the electronics in my '93. For those that don't, I've completely gutted the interior and electronics of the car and have been having problems with the security system keeping the car from running.
It's currently a liveable problem, but I am having an intermittant stall condition that happens the first time I drive the car after sitting for a day or two. It seems to go away after I reset everything and let the car sit for a few minutes. Unfortunately this tends to happen my first session on the track...not safe. I have tried letting the car idle for awhile, but it doesn't occur until I take it out on the road.
Has anyone successfully eliminated their body computer (CCM) from the early LT-1 cars? All of the security is in that module, so I can't figure out how to remove it. The ECM PROM's I've looked into which claim to eliminate the VATS system only seem to answer the pass-key part, which I've long removed by bridging the inputs with the equivilant resistor.
This winter I'll remove the entire harness and computer and replace with aftermarket, but to do that now would make me miss too many track days.
Anyone have an interim solution?
It's currently a liveable problem, but I am having an intermittant stall condition that happens the first time I drive the car after sitting for a day or two. It seems to go away after I reset everything and let the car sit for a few minutes. Unfortunately this tends to happen my first session on the track...not safe. I have tried letting the car idle for awhile, but it doesn't occur until I take it out on the road.
Has anyone successfully eliminated their body computer (CCM) from the early LT-1 cars? All of the security is in that module, so I can't figure out how to remove it. The ECM PROM's I've looked into which claim to eliminate the VATS system only seem to answer the pass-key part, which I've long removed by bridging the inputs with the equivilant resistor.
This winter I'll remove the entire harness and computer and replace with aftermarket, but to do that now would make me miss too many track days.
Anyone have an interim solution?
08-01-2005, 07:12 PM
#6
Safety Car
Thread Starter
I have a HELMS and have poured over the two pinouts. The only link appears to be the serial communication link. I'm guessing there's a message from the CCM to the ECM to allow the car to run. Therefore, there is no way to mimic the message (I'd have to rig up a signal generator to send the pulses...), so I need a way for the ECM to not need the message.
My current solution is to tell the CCM that everything's ok so it can relay the message to the ECM. But obviously this is not without flaw, as posted above.
Therein lies the rub.
And I really hate the rub.
My current solution is to tell the CCM that everything's ok so it can relay the message to the ECM. But obviously this is not without flaw, as posted above.
Therein lies the rub.
And I really hate the rub.
08-01-2005, 08:16 PM
#7
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Originally Posted by ScaryFast
There are a couple of security inputs to the CCM (under the dash), but which line communicates to the ECM (under the hood)to tell it to cut off the fuel once it's running? That's the line I need to fool so the ECM thinks life is grand.
RACE ON!!!
08-01-2005, 10:29 PM
#8
Le Mans Master
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Originally Posted by ScaryFast
I have a HELMS and have poured over the two pinouts. The only link appears to be the serial communication link. I'm guessing there's a message from the CCM to the ECM to allow the car to run. Therefore, there is no way to mimic the message (I'd have to rig up a signal generator to send the pulses...), so I need a way for the ECM to not need the message.
My current solution is to tell the CCM that everything's ok so it can relay the message to the ECM. But obviously this is not without flaw, as posted above.
Therein lies the rub.
And I really hate the rub.
My current solution is to tell the CCM that everything's ok so it can relay the message to the ECM. But obviously this is not without flaw, as posted above.
Therein lies the rub.
And I really hate the rub.
The system is relatively simple. The CCM and the ECM communicates on the two serial data links at pins D4 and D14 on the ECM side. The CCM sends a fuel enable signal to the ECM which in turn allows the injectors to pulse, when it sees the correct resistor value in the key. It also allows the starter enable relay to close to allow current flow to the starter when the key is in the start position. Having a prom that is properly set ot disable the VATs system should be all that you need to disable the VATs system from the ECM code. Once its running it should stay running, especially if the starter turns over that means that the CCM is satisfied and it is closing the starter enable relay.
Who programmed your chip? If it wasn't programmed properly I can see the VATs system to prevent the starting of your engine. It does this by disabling the injectors and not the fuel pump itself. The fuel pump would run irregardless once enough oil pressure is built up to close the oil pressure/fuel pump switch.
08-01-2005, 11:22 PM
#9
Safety Car
Thread Starter
It's a stock chip. I've eliminated the pass key with a resistor directly across the two pins on the CCM.
I guess when I say "fuel cut off" I should be more specific - the injectors are not firing. So I don't think I can hardwire them directly, otherwise that would be the perfect solution.
Doesn't anyone program a stand alone PROM that doesn't need any inputs from other modules to run the damn motor?
I guess when I say "fuel cut off" I should be more specific - the injectors are not firing. So I don't think I can hardwire them directly, otherwise that would be the perfect solution.
Doesn't anyone program a stand alone PROM that doesn't need any inputs from other modules to run the damn motor?
08-01-2005, 11:41 PM
#10
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Originally Posted by ScaryFast
It's a stock chip. I've eliminated the pass key with a resistor directly across the two pins on the CCM.
I guess when I say "fuel cut off" I should be more specific - the injectors are not firing. So I don't think I can hardwire them directly, otherwise that would be the perfect solution.
Doesn't anyone program a stand alone PROM that doesn't need any inputs from other modules to run the damn motor?
I guess when I say "fuel cut off" I should be more specific - the injectors are not firing. So I don't think I can hardwire them directly, otherwise that would be the perfect solution.
Doesn't anyone program a stand alone PROM that doesn't need any inputs from other modules to run the damn motor?
The problem is that maybe your resistor fix isn't exactly perfect as to what the CCM wants to see, with heat resistors often change values a bit, and that can cause your problems. Not to mention that most resistors have a minimum of a 5% tolerance for error and with some cheap Radio Shack can go as high as 10% error.
08-02-2005, 09:48 AM
#11
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This company sells a module that generates a 50hz square wave (which I believe is the one you need) or 30hz signal to fool the ECM so the injectors will be pulsed.
As was mentioned, once the engine is running, the signal is not needed until you restart the engine.
http://mysite.verizon.net/vze7erz1/id1.html#vatsmod
I looked at the Helms manual and see what you mean about the hand shaking between the PCM and BCM.
Appears the item above will not work on the 93 Corvette.
As was mentioned, once the engine is running, the signal is not needed until you restart the engine.
http://mysite.verizon.net/vze7erz1/id1.html#vatsmod
I looked at the Helms manual and see what you mean about the hand shaking between the PCM and BCM.
Appears the item above will not work on the 93 Corvette.
Last edited by Hooked on Vettes; 06-10-2014 at 09:34 PM.
08-02-2005, 11:09 AM
#12
Safety Car
Thread Starter
This is a tough thing to explain, but I'll try because I need this issue GONE! Bear with me on the lengthy post, but all of the info needs to be known for you guys to help out.
I have no door locks or PKE. The steering column is removed so I have no ignition key, either. I have an ignition switch and a start button. I've bypassed the resistor in the start key by putting the equivilant resistor directly across the two inputs to the CCM. I had a start/stall condition for awhile that we worked through on here a few weeks ago. Turns out that the resistor was allowing the starter to crank, however I discovered an additional input to the CCM called "securtity system disable" (green wire, can't remember the pin#) that needs to be pulsed to ground. This simulates the PKE or using a key to unlock the door. It's a one time pulse to ground prior to ignition "on".
Once the CCM gets this pulse, everything is a-ok until the car is locked, rearming the system. My car is never locked so the system never armed and things were great for two months. However, I recently installed a battery kill switch for safety reasons and to keep my battery from draining when the car sits (it's a track only car). Now, due to the fact that the CCM loses battery, it forgets that the system was disarmed and re-arms it every time. This was the cause of my aforementioned "start then stall" condition.
By installing a switch at that disable input, I can turn on the battery, pulse the disable input to ground, turn on ignition and viola, the car starts. Not only is this an irritating fix but I don't think it is flawless, as sometimes after driving for several minutes the car shuts off the injectors again and the car stalls. Resetting everything and sitting for a minute rectifies the bug, but it's obvious that this is unacceptable.
I need to completely eliminate the security system from interfering with my ECM and I can't figure out how to do that. All of the VATS elimination modules I've looked at seem to only replace the key portion.
Does anyone know enough about the communication between the two modules? My assumption would be that the CCM gets all of these inputs (pass-key and the additional disable) and sends one message to the ECM that everything's ok, so run the car. In addition, both VATS modules I've looked at interface with pin #19 on the red ECM connector, and my car does not have anything connected to that input at all! It never did, even when it was a street car.
Whomever invented the VATS system needs to be maimed. Look on the forum, there are 3 to 5 active posts at any given time about this stuff.
I appreciate everybody's patience and help!
I have no door locks or PKE. The steering column is removed so I have no ignition key, either. I have an ignition switch and a start button. I've bypassed the resistor in the start key by putting the equivilant resistor directly across the two inputs to the CCM. I had a start/stall condition for awhile that we worked through on here a few weeks ago. Turns out that the resistor was allowing the starter to crank, however I discovered an additional input to the CCM called "securtity system disable" (green wire, can't remember the pin#) that needs to be pulsed to ground. This simulates the PKE or using a key to unlock the door. It's a one time pulse to ground prior to ignition "on".
Once the CCM gets this pulse, everything is a-ok until the car is locked, rearming the system. My car is never locked so the system never armed and things were great for two months. However, I recently installed a battery kill switch for safety reasons and to keep my battery from draining when the car sits (it's a track only car). Now, due to the fact that the CCM loses battery, it forgets that the system was disarmed and re-arms it every time. This was the cause of my aforementioned "start then stall" condition.
By installing a switch at that disable input, I can turn on the battery, pulse the disable input to ground, turn on ignition and viola, the car starts. Not only is this an irritating fix but I don't think it is flawless, as sometimes after driving for several minutes the car shuts off the injectors again and the car stalls. Resetting everything and sitting for a minute rectifies the bug, but it's obvious that this is unacceptable.
I need to completely eliminate the security system from interfering with my ECM and I can't figure out how to do that. All of the VATS elimination modules I've looked at seem to only replace the key portion.
Does anyone know enough about the communication between the two modules? My assumption would be that the CCM gets all of these inputs (pass-key and the additional disable) and sends one message to the ECM that everything's ok, so run the car. In addition, both VATS modules I've looked at interface with pin #19 on the red ECM connector, and my car does not have anything connected to that input at all! It never did, even when it was a street car.
Whomever invented the VATS system needs to be maimed. Look on the forum, there are 3 to 5 active posts at any given time about this stuff.
I appreciate everybody's patience and help!
