Check Engine Light On, ECM Problem?
Safety Car
Joined: May 2001
Posts: 3,758
Likes: 3
From: Surrey
Ignore the pics in the manual! Some of those connectors were fitted **** about face so the terminals to jump are the leftmost pair on some cars & the rightmost pair on others. The giveaway is the slot cut in the divider wall between the pair to jump.
Drifting
Joined: Jul 2002
Posts: 1,995
Likes: 110
From: Garland Texas
Are you checking it with the key on and engine off? You should be getting code 12.
Flash-1/2 second pause- flash flash - one second pause- flash-1/2 second pause- flash flash and so on. It will repeat code 12 three times and then flash the next code three times etc. When it's done it will repeat the whole sequence starting with code 12.
Mike
Flash-1/2 second pause- flash flash - one second pause- flash-1/2 second pause- flash flash and so on. It will repeat code 12 three times and then flash the next code three times etc. When it's done it will repeat the whole sequence starting with code 12.
Mike
Thread Starter
Intermediate
Joined: May 2005
Posts: 41
Likes: 0
From: In the Garage Drink'in beer in Michigan
Originally Posted by tracdogg2
Are you checking it with the key on and engine off? You should be getting code 12.
Flash-1/2 second pause- flash flash - one second pause- flash-1/2 second pause- flash flash and so on. It will repeat code 12 three times and then flash the next code three times etc. When it's done it will repeat the whole sequence starting with code 12.
Mike
Flash-1/2 second pause- flash flash - one second pause- flash-1/2 second pause- flash flash and so on. It will repeat code 12 three times and then flash the next code three times etc. When it's done it will repeat the whole sequence starting with code 12.
Mike
Race Director
Joined: Jul 2004
Posts: 12,657
Likes: 328
From: Scottsdale Arizona
Originally Posted by Lovin_my_81
Yea, and I can't see any pauses at all. it just keeps flashing constant.
I don't think this is good. Let me check the service manual when I get home and I'll post what it says later.
Is the M/C solenoid cycling (clicking) while it flashes continually?
Thread Starter
Intermediate
Joined: May 2005
Posts: 41
Likes: 0
From: In the Garage Drink'in beer in Michigan
I can hear a clicking (when its flashing) on the firewall drivers side. I'll check it when I get home and check in later.
Correction the M/C solenoid is on the carb right? I think the MAP sensor is what seems to be clicking. its mounted on the firewall drivers side.
Correction the M/C solenoid is on the carb right? I think the MAP sensor is what seems to be clicking. its mounted on the firewall drivers side.
Last edited by Lovin_my_81; Jun 9, 2005 at 01:31 PM.
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Race Director
Joined: Jul 2004
Posts: 12,657
Likes: 328
From: Scottsdale Arizona
Originally Posted by CA-Legal-Vette
I don't think this is good. Let me check the service manual when I get home and I'll post what it says later.
What it says to do is check the voltage on ECM terminal 21 (second from the top on the left column). Should be more than 4 volts (nominal of 5 volts). If less than 4 volts, check for grounded circuit at ECM 5. If not grounded, the ECM is faulty. If more than 4 volts, check for grounded circuit at ECM 19. If not grounded, the ECM is faulty.
A little cryptic, but essentially it is looking for shorted circuits to account for the flashing.
Cruising
Joined: May 2005
Posts: 10
Likes: 0
From: Ontario ON
Sorry to jump in but this is related 
I just had the ECM replaced on my '81, was doing the exact same thing when trying to get the codes, and even when the car was running, and causing a relay on the carb to chatter, showing a 55 code, so i had it changed. Now the 55 is gone, the computer seems to be working, but the engine light is on constantly. Any ideas?? Bad ground?
I just had the ECM replaced on my '81, was doing the exact same thing when trying to get the codes, and even when the car was running, and causing a relay on the carb to chatter, showing a 55 code, so i had it changed. Now the 55 is gone, the computer seems to be working, but the engine light is on constantly. Any ideas?? Bad ground?
Thread Starter
Intermediate
Joined: May 2005
Posts: 41
Likes: 0
From: In the Garage Drink'in beer in Michigan
Originally Posted by drp5862
Sorry to jump in but this is related I just had the ECM replaced on my '81, was doing the exact same thing when trying to get the codes, and even when the car was running, and causing a relay on the carb to chatter, showing a 55 code, so i had it changed. Now the 55 is gone, the computer seems to be working, but the engine light is on constantly. Any ideas?? Bad ground?
I just had the ECM replaced on my '81, was doing the exact same thing when trying to get the codes, and even when the car was running, and causing a relay on the carb to chatter, showing a 55 code, so i had it changed. Now the 55 is gone, the computer seems to be working, but the engine light is on constantly. Any ideas?? Bad ground?Also to anyone reading these posts I am considering purchasing an OTC 2000 scanner are they worth it?
Safety Car
Joined: Aug 2000
Posts: 3,711
Likes: 43
From: San Antonio TX
Originally Posted by Lovin_my_81
...Also to anyone reading these posts I am considering purchasing an OTC 2000 scanner are they worth it?
Honestly, you'd do better with some of the more up to date scanners made for the consumer market. These won't have a lot of the enhanced features(reading proprietary codes and such) of the professional scanners but you'd very rarely use those anyway. For the most part, you want to read and erase codes, maybe get a little smart help on the codes and circuits, read the datastreams(as long as you know what the sensor outputs are supposed to look like) and that's really about all you can use without a lot of technical training. Plus, the newer the scanner, the more cars you'll be able to use it on. Many of the OEMs (particularly GM) are using the CAN protocol and the comm busses are completely different and can't be read by a scanner more than a couple years old. I have two CAN cars and my scanner won't do a damn thing with either of them.
Safety Car
Joined: May 2001
Posts: 3,758
Likes: 3
From: Surrey
Originally Posted by Lovin_my_81
OK to jump in I read your postings now too, what I need to know now is where exactly is the ECM? I can't seem to locate it under the dash.
Thread Starter
Intermediate
Joined: May 2005
Posts: 41
Likes: 0
From: In the Garage Drink'in beer in Michigan
Well thanks to the help of this forum I have found the problem with the ECM and why it was flashing consitantly. When I finally found it (thanks Paul) I took it completely out and inspected the plug terminals to find a broken strip on the board. We repaired the break with some solder and now I have no more check engine light on. I only wish I had joined this forum a year ago when I started working on this!!!!!!!!!!
Thanks again to everyone, you guys Rock!!!
Thanks again to everyone, you guys Rock!!!
