code 12 flashing with car running!?!?!

[billygeg]

Just got my 85 GN running today! It needed a new fuel pump. The car is flashing 12 on the engine light while its running. The car Starts up but runs like crap...Black smoke, shaking, stalling, etc...It runs like this for alittle while then seems to settle down and run alittle better but maybe 10 seconds later it dies..The car has been sitting for years..The tank was taken down and old gas removed. Do I need to run it for a while or?

Thanks guys! :smile:

 

[garyk1970]

check the ANDL(ecm )plug under drivers side of stereo housing for something inserted in the a &b port.....sounds like its in diagnostic mode....

look here http://www.gnttype.org/maint/malf.html

 

[gsgns4me]

Start Troubleshooting Here

 

[garyk1970]

i wouldnt run the engine untill you find/remove the "key",paper clip,or whatever is grounding the dignostic circuit.

 

[billygeg]

Thats what I thought it might be but I am new to Grand Nationals. I had a clip in the other day but got nothing except for code 12 which kept blinking even with the car in the on Position. I have to trace it out. Does that clip run directly to the computer?
Thanks! Bill

 

[billygeg]

Very Very Helpful page! Thanks! I have to check circuit 451 tomorrow. Hopefully I can find the short without too much of a hassle. I'm an electrician so it shouldnt be too hard but you never know!
Thanks again!

 

[billygeg]

I trouble shot everything I was told too. B on the ALDL is not shorted to a and it not shorted to ground. There is a section of the malfunction code description that sayd exactly this...

Trouble Code 12 is a special case code that is not logged into the ECM's Non-Volatile Memory (NVM) when detected. When the ignition is "ON" and the ECM detects no ignition reference pulses coming from the ignition module, it illuminates the Service Engine Soon lamp.

Could this be a problem with the ignition module or the wire coming from it?

 

[gsgns4me]

If you followed the charts and didn't skip any steps, it sounds like a bad ECM.

 

[billygeg]

Just want to let you know that the chart 1 on the NO SES light troubleshooting tree is not completely correct. It says, with the ECM harness disconnected to prob ckt 419 to ground from your ecm connector at location A5 and the SES light should come on. This is not completely true. I checked the ckt today and instead of the SES light coming on the probe bulb came on. The hot leg that feeds the SES bulb runs directly threw the filament of the bulb to the ecm harness, Where it is then grounded by the ecm while the key is on (motor not running) or in test mode which makes the ligth come on. If You put a test light on it the test light will light up. Not the SES light. If you take that ckt and ground it directly witout the test light the SES light will come on. Not that its a big deal. I figured it out but it may be confusing to some people and screw them all up. I'm a newbie and just thought I would sahre this info with you this way you can inform others.

Thanks for all the help! Bill

 

[mrtiptop]

mrtiptop

This helped me and won't do any harm !
I removed the lower Radiator Hose from the Water Pump and there it is the Ground connections !
Three wire eyes with two wires in each !
There is also a wire harness bracket there also !
Using a 15mm socket take everything apart and clean everything real good !
I used Brake Parts Cleaner and a Dremmel with a wire brush and spent some time cleaning REAL REAL good ! ! !