Intermittent Electrical Problem
Thread Starter
Instructor
Joined: Jul 2003
Posts: 130
Likes: 2
From: Fairfax, VA
Intermittent Electrical Problem
I hope someone out in Corvertte-Land can help me.
Here are the symptoms:
Driving along normally, minding my own business, when suddenly I feel a ½ second loss of power and the following symptoms:
ASR light comes on
Speedometer goes to zero
Idle jumps to 1500 RPM
Service Engine light comes on
Security light starts to flash
Transmission won't downshift
Low power
Won’t accelerate
Jerky performance
Distinct odor wafting into the interior – heavy – rotten eggs/pungent/partially burned gas smell
Seems like the primary computer goes whacky, so the car flips over to a backup computer so I can crawl home.
This has been happening daily for one week
Couldn’t pull engine codes (it is OBD I) I have OBD II reader
I am thinking it is a connector or ground problem. Reseated many connections under the hood. Seems better - but still misbehaving.
Any brilliant ideas?
Thanks!
Here are the symptoms:
Driving along normally, minding my own business, when suddenly I feel a ½ second loss of power and the following symptoms:
ASR light comes on
Speedometer goes to zero
Idle jumps to 1500 RPM
Service Engine light comes on
Security light starts to flash
Transmission won't downshift
Low power
Won’t accelerate
Jerky performance
Distinct odor wafting into the interior – heavy – rotten eggs/pungent/partially burned gas smell
Seems like the primary computer goes whacky, so the car flips over to a backup computer so I can crawl home.
This has been happening daily for one week
Couldn’t pull engine codes (it is OBD I) I have OBD II reader
I am thinking it is a connector or ground problem. Reseated many connections under the hood. Seems better - but still misbehaving.
Any brilliant ideas?
Thanks!
Race Director
Joined: Sep 2005
Posts: 10,878
Likes: 1
St. Jude Donor '07
Sounds like your cat is plugging up when warm. It may be causing back pressure and pushing thru a joint causing the smell. This could trip all sorts of codes and set your computer to 'limp home' mode.
Thread Starter
Instructor
Joined: Jul 2003
Posts: 130
Likes: 2
From: Fairfax, VA
Very interesting possibility. I will try to have it checked out.
Drifting
Joined: Aug 2006
Posts: 1,326
Likes: 18
From: Los Angeles California
It is imperative that you find out what code is being thrown. Why not take advantage of that available information about what the problem is. Do a search for the paperchip method, which allows you to pull OBD-1 codes from this car without a scanner.
Burning Brakes
Joined: Jun 2005
Posts: 1,113
Likes: 35
From: LaUgH, mOrE!
Have you tried cleaning up the battery cables--especially the negative battery cable? If not, take a wire brush and clean the cable bolt and the battery post/inside screw hole really well. A loose/oxidized negative battery cable connection can cause all sorts of strange things to happen.
Thread Starter
Instructor
Joined: Jul 2003
Posts: 130
Likes: 2
From: Fairfax, VA
Have you tried cleaning up the battery cables--especially the negative battery cable? If not, take a wire brush and clean the cable bolt and the battery post/inside screw hole really well. A loose/oxidized negative battery cable connection can cause all sorts of strange things to happen.
I did notice that the neg. battery terminal is quite corroded.... I will clean it tomorrow also.
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Drifting
Joined: Aug 2006
Posts: 1,326
Likes: 18
From: Los Angeles California
Couldn't be farther from the truth. Twelve years was a long time for the C4 to undergo changes. The 1984 was a rather electrically simple and carbed. By 1996 it was a complicated wiring jungle with numerous technical issues fixed, the whole interior changed, not to mention every engine piece and everything in the engine bay was changed.
Team Owner
Joined: Oct 2004
Posts: 35,065
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From: Bergen County, NJ Democrats, doing for the country what they did for Michigan
Safety Car
Joined: Feb 1999
Posts: 3,504
Likes: 4
From: Mexico Beach FL
I wouldn't bet on it at this time, but if all else fails, the '92 and '93 ECM is notorious for problems -- and, from what I've seen in other posts, it's nearly impossible to get a new/refurbished one.
The ECM (engine computer) and CCM (body computer) communicate over a serial bus.
If one of these computers fails to commumicate with the other, strange things happen -- the symptom of the "Security" light flashing comes to mind.
If this communications breaks down, the "SYS" usually flashes in the dash display.
Tom Piper
The ECM (engine computer) and CCM (body computer) communicate over a serial bus.
If one of these computers fails to commumicate with the other, strange things happen -- the symptom of the "Security" light flashing comes to mind.
If this communications breaks down, the "SYS" usually flashes in the dash display.
Tom Piper
Thread Starter
Instructor
Joined: Jul 2003
Posts: 130
Likes: 2
From: Fairfax, VA
I wouldn't bet on it at this time, but if all else fails, the '92 and '93 ECM is notorious for problems -- and, from what I've seen in other posts, it's nearly impossible to get a new/refurbished one.
The ECM (engine computer) and CCM (body computer) communicate over a serial bus.
If one of these computers fails to commumicate with the other, strange things happen -- the symptom of the "Security" light flashing comes to mind.
If this communications breaks down, the "SYS" usually flashes in the dash display.
Tom Piper
The ECM (engine computer) and CCM (body computer) communicate over a serial bus.
If one of these computers fails to commumicate with the other, strange things happen -- the symptom of the "Security" light flashing comes to mind.
If this communications breaks down, the "SYS" usually flashes in the dash display.
Tom Piper
You are speaking my language! When the system is misbehaving, if I tap the ECU the lights will extinguish, which tells me it is something in the ECU. Are they repairable or do I have to get a new one?
Burning Brakes
Joined: Jun 2005
Posts: 1,113
Likes: 35
From: LaUgH, mOrE!
You may want to try some Deoxit or Deoxit Gold on all the cable connections to clean/recondition them (good stuff--can buy it at a Radio Shack). You may get lucky and it just be oxidized electrical contacts between the connections... and not the entire ECM, etc.
Thread Starter
Instructor
Joined: Jul 2003
Posts: 130
Likes: 2
From: Fairfax, VA
Thread Starter
Instructor
Joined: Jul 2003
Posts: 130
Likes: 2
From: Fairfax, VA
I reseated all my connections - and they all looked clean, I may try your cleaner.