Help '96 LT4 electrical problems...ECM bad?
Thread Starter
Advanced
Joined: Sep 2007
Posts: 83
Likes: 1
From: Tucson AZ
Help '96 LT4 electrical problems...ECM bad?
Hello. Recently the two left front turn signal/parking lights stuck ON along with the left turn indicator. They just came on after sitting parked a few hours. With the key out nothing should happen, but by switching down (as in a left turn) the left headlight would pop up and stay up, but not on. Turning the headlights on and off would operate the headlights properly and return them both stowed. I had to pull the 2 bulbs to save the battery but the dash indicator stayed on. I removed the bottom of the dash and handled all the wiring pushing in at the connectors. The problem has cleared for now. Prior to this, once I set the PKE keys on the console to keep the car from locking while I was working on it and the doors closed. It locked itself and the PKE battery was good so... weird again. The PKE wouldn't wake up by rocking the car like the manual says. Now the Delayed Accessory Bus is powering the radio with door open and keys out. (has happened before) I have to be sure to turn off the radio. Is the ECM to blame? I have the shop manual and the only thing in common that I can see is the ECM. Where can I buy one that's not too expensive. Thanks for any help.
Instructor
Joined: Feb 2006
Posts: 144
Likes: 0
From: Woodlands TX
I seem to be having similar problems with my 96.
In the past I fought O2 sensors that seemed to go bad for no reason.
Now, my door chimes work when they want and when they do they are pitifully weak and on and off in nature.
My right headlamp motor runs when it shouldn't (turning off just parking lights) and runs longer when than the left when stowing the lights.
My AC temp control works most of the time but sometime won't let me adjust the temp up or down or some times only down.
I am not really sure just how much the ECM controls but I am beginning to wonder about mine. Where did you find the information that you mentioned pointed to the ECM?
In the past I fought O2 sensors that seemed to go bad for no reason.
Now, my door chimes work when they want and when they do they are pitifully weak and on and off in nature.
My right headlamp motor runs when it shouldn't (turning off just parking lights) and runs longer when than the left when stowing the lights.
My AC temp control works most of the time but sometime won't let me adjust the temp up or down or some times only down.
I am not really sure just how much the ECM controls but I am beginning to wonder about mine. Where did you find the information that you mentioned pointed to the ECM?
Thread Starter
Advanced
Joined: Sep 2007
Posts: 83
Likes: 1
From: Tucson AZ
I seem to be having similar problems with my 96.
In the past I fought O2 sensors that seemed to go bad for no reason.
Now, my door chimes work when they want and when they do they are pitifully weak and on and off in nature.
My right headlamp motor runs when it shouldn't (turning off just parking lights) and runs longer when than the left when stowing the lights.
My AC temp control works most of the time but sometime won't let me adjust the temp up or down or some times only down.
I am not really sure just how much the ECM controls but I am beginning to wonder about mine. Where did you find the information that you mentioned pointed to the ECM?
In the past I fought O2 sensors that seemed to go bad for no reason.
Now, my door chimes work when they want and when they do they are pitifully weak and on and off in nature.
My right headlamp motor runs when it shouldn't (turning off just parking lights) and runs longer when than the left when stowing the lights.
My AC temp control works most of the time but sometime won't let me adjust the temp up or down or some times only down.
I am not really sure just how much the ECM controls but I am beginning to wonder about mine. Where did you find the information that you mentioned pointed to the ECM?
Burning Brakes
Joined: Jan 2006
Posts: 854
Likes: 1
From: The burbs of Denver CO
One thing repeated in the fsm is that many people blame problems on the ecm, and in almost all of the cases that is not the source of the problem. The ecm very rarely fails. Check your fsm first for diagnostics!
Advanced
Joined: Aug 2007
Posts: 52
Likes: 0
I have plenty of electrical problems myself. I replaced the ECM, nothing changed. ASR is also has a huge problem where when I manually reset the rear computer it just stays on. This car is a POS and I am to the point of going crazy, I have another CCM to put in but its far and hard to get to. Its all apart as we speak. Have to dissasemble the entire dash frame to get access..
Team Owner
Joined: Aug 2000
Posts: 40,156
Likes: 45
From: San Pedro CA
Jesus Christ.
What part of the turn signals does the ECM control? The ABS is somewhat independant of the ECM, but does need the Data Serial Line working to function properly.
This is for all of you: Unass the 100.00 and get the damned FSM. Use the diagrams to debug this correctly, don't throw parts and money at it uselessly. That's just a waste of money and does nothing than **** people off and make them hate the car, when they should simply be self loathing.
As for the turn signals, the constant on says to me the flasher relay is bad, or, you have corrosion in the sockets. Remember two big rules for fixing anything: Keep It Simple, Stupid and Occam's Razor: The simplest solution is usually the best.
What part of the turn signals does the ECM control? The ABS is somewhat independant of the ECM, but does need the Data Serial Line working to function properly.
This is for all of you: Unass the 100.00 and get the damned FSM. Use the diagrams to debug this correctly, don't throw parts and money at it uselessly. That's just a waste of money and does nothing than **** people off and make them hate the car, when they should simply be self loathing.
As for the turn signals, the constant on says to me the flasher relay is bad, or, you have corrosion in the sockets. Remember two big rules for fixing anything: Keep It Simple, Stupid and Occam's Razor: The simplest solution is usually the best.
Advanced
Joined: Aug 2007
Posts: 52
Likes: 0
replacing my CCM did this: No more heater/ac unit problems where its either 85 degrees or 90 where its either cold or burning hot. I believe no more lcd flickering. But I just figured out my Service ASR light (which is always on no matter what even when resetting) is probably due to my rear ASR computer being replaced with a '92 Corvette's computer.. ASR worked for a day with the '92 Corvette's module in it. The original ASR unit was gold and this one is silver. Time to find the correct year as the 92 corvette's wiring harness to the rear ASR is different also.
FYI bogus.. My part shopping/self diagnostic approach actually worked for the same or less than $100 for manual + the parts. $25 for a ASR/ABS module, $55 for CCM. $30 for ASR wiring harness. Since 2/3 these parts I wont be needing, I can now sell them and then I can afford a '94 'Vettes rear ASR/ABS computer and be done with all my ASR problems. The heater and lcd problems are now fixed from failing CCM, 201k miles. My father is a locksmith so the VATS was no problem, we can program later.
No offense here. Atleast this way its a challenge to use your brain instead of a book guiding you
I love my car 90% of the time, 300k here we come!
FYI bogus.. My part shopping/self diagnostic approach actually worked for the same or less than $100 for manual + the parts. $25 for a ASR/ABS module, $55 for CCM. $30 for ASR wiring harness. Since 2/3 these parts I wont be needing, I can now sell them and then I can afford a '94 'Vettes rear ASR/ABS computer and be done with all my ASR problems. The heater and lcd problems are now fixed from failing CCM, 201k miles. My father is a locksmith so the VATS was no problem, we can program later.
No offense here. Atleast this way its a challenge to use your brain instead of a book guiding you
I love my car 90% of the time, 300k here we come!
Last edited by 94vetten73stang; Dec 17, 2007 at 02:02 AM.
