OBD 1 sometimes doesn't give even 12 code
Thread Starter
Intermediate
Joined: Jan 2006
Posts: 34
Likes: 1
OBD 1 sometimes doesn't give even 12 code
I have a problem with the OBD 1 system in a 1992 not responding to give codes. Sometimes it will give the 12 code (ecm working ok) and sometimes it doesn't. Also, sometimes engine runs normal and sometimes it runs everything in the defalt (limp home) mode.
I disconnected and cleaned all the plugs going to the computer with contact cleaner. They all seemed clean and tight.
Any ideas what's going on?
Bob
I disconnected and cleaned all the plugs going to the computer with contact cleaner. They all seemed clean and tight.
Any ideas what's going on?
Bob
Team Owner
Joined: Aug 2000
Posts: 40,156
Likes: 45
From: San Pedro CA
that's wierd... I would think it would work or not... any drivability problems?
C4 Guru - Reading CCM Codes 1992/93
C4 Guru - Reading CCM Codes 1992/93
Cruising
Joined: Sep 2006
Posts: 14
Likes: 0
From: Clovis, California
Mine (1990 C4) doesn't get a C12 code either but I do get a C41 Code (not communicating with the ECM via the serial data connection) ... car seems to run fine but can't pull codes off of the ECM via my OBD-I code reader and SYS light flashes. Mine is a constant not intermitent problem.
I ordered a new ECM and will see if that makes a difference ...
I ordered a new ECM and will see if that makes a difference ...
Racer
Joined: Jun 2006
Posts: 408
Likes: 0
From: Elkton MD
No 12 DTC
Had a '91 Regal that did that (no code 12, sporadic failure to start, occasional shut down right out of the blue). Found a Helms service manual and it said to check the ECM ground (a big lug with a fat wire to the block) and if ground was OK to look for the service engine light on when in the diagnostic mode (pins shorted in the connector).
The ground was OK and the service engine light wasn't on when the pins were shorted. The service manual said replace the ECM. New ECM, no more erratic behavior.
Don't know if the advice re: "looking for the service engine light while the pins are shorted" applies to your Corvette. Do you have a Helms service manual that you could check?
The ground was OK and the service engine light wasn't on when the pins were shorted. The service manual said replace the ECM. New ECM, no more erratic behavior.
Don't know if the advice re: "looking for the service engine light while the pins are shorted" applies to your Corvette. Do you have a Helms service manual that you could check?
Last edited by IRAraid; Nov 19, 2006 at 05:44 PM.
Pro
Joined: Feb 2005
Posts: 531
Likes: 0
From: Manama Bahrain
Originally Posted by IRAraid
Had a '91 Regal that did that (no code 12, sporadic failure to start, occasional shut down right out of the blue). Found a Helms service manual and it said to check the ECM ground (a big lug with a fat wire to the block) and if ground was OK to look for the service engine light on when in the diagnostic mode (pins shorted in the connector).
The ground was OK and the service engine light wasn't on when the pins were shorted. The service manual said replace the ECM. New ECM, no more erratic behavior.
Don't know if the advice re: "looking for the service engine light while the pins are shorted" applies to your Corvette. Do you have a Helms service manual that you could check?
The ground was OK and the service engine light wasn't on when the pins were shorted. The service manual said replace the ECM. New ECM, no more erratic behavior.
Don't know if the advice re: "looking for the service engine light while the pins are shorted" applies to your Corvette. Do you have a Helms service manual that you could check?
Racer
Joined: Jun 2006
Posts: 408
Likes: 0
From: Elkton MD
ECM ground
Originally Posted by honda hunter
On 92-93's is this the ground located near the oil filter?
But the ground on the Buick Regal was separate from the other plugs, a fat wire leading to the engine - really easy to spot once the ECM was out of its bracket.
Thread Starter
Intermediate
Joined: Jan 2006
Posts: 34
Likes: 1
Originally Posted by IRAraid
Had a '91 Regal that did that (no code 12, sporadic failure to start, occasional shut down right out of the blue). Found a Helms service manual and it said to check the ECM ground (a big lug with a fat wire to the block) and if ground was OK to look for the service engine light on when in the diagnostic mode (pins shorted in the connector).
The ground was OK and the service engine light wasn't on when the pins were shorted. The service manual said replace the ECM. New ECM, no more erratic behavior.
Don't know if the advice re: "looking for the service engine light while the pins are shorted" applies to your Corvette. Do you have a Helms service manual that you could check?
The ground was OK and the service engine light wasn't on when the pins were shorted. The service manual said replace the ECM. New ECM, no more erratic behavior.
Don't know if the advice re: "looking for the service engine light while the pins are shorted" applies to your Corvette. Do you have a Helms service manual that you could check?
Bob
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