need help code 42 with twist
Thread Starter
Instructor
Joined: Nov 2008
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From: fort smith ar
need help code 42 with twist
I know there is alot of info on here about code 42 for 94 models but none which sound like my problem. It did start about like all the rest, dying not wanting to start. I replaced the opti, ICM, plugs, wires, coil, water pump, checked all my grounds. It starts and runs, heres the twist after it warms up the code goes away and runs fine, it only does it when it is cold. When I start the car cold the fan comes on it idles at 900 rpm, after it warms up the AIR pump come on for about 8 seconds and goes off, it turns the fan off and the code goes away and it runs fine. I manage a GMC body shop so I took it to the shop and put on the tech 2, everything checks out except code 42, the tech 2 shows it to be in open loop when all this is happening, when it goes into closed loop all is well. Any suggestion would be help. thank you.Mark
Le Mans Master
Joined: Jan 2006
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From: Orlando FL
All those events that are happening are functions of the PCM. It controls all those things by inputs from other sensors. There is so much that is not happening right that it’s a possibility the PCM is defective itself. Substitution is the best way to confirm that diagnosis and not spend days troubleshooting around and checking it all. Finding one to borrow might be tough to do but definitely will give you the answer.
Thread Starter
Instructor
Joined: Nov 2008
Posts: 177
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From: fort smith ar
replace the pcm, doing same thing except there isn't any code showing when the engine light is on.
heelllppp. my shop cant figure it out..
also changed the coolant temp sensor, and the tps. running out of sensors and money...
heelllppp. my shop cant figure it out..also changed the coolant temp sensor, and the tps. running out of sensors and money...
Thread Starter
Instructor
Joined: Nov 2008
Posts: 177
Likes: 0
From: fort smith ar
its fixed!!!!!!!!!!!! after almost 3 months, i finally found someome who new what he was doing, the aftermarket ignition control module was bad. this was the second aftermarket one i had put on to correct the problem. he put on a new a/c delco and the rest is history.
