Got a 1995 GMC Sonoma. Need help identifying OBDI or OBDII

[dennis524]

This truck has the OBDII DLC but from what I understand it should have 16 pins.
This one only has 4 pins. My Actron scan tool will connect but I get an error message saying can’t communicate with vehicle. The OBDI has a different shaped DLC and supposed to have 8 pins.
The truck is fuel injected and no distributer.
The truck will turn over and fire but not start and backfires.
The service engine light is on but can’t access the trouble code.
Truck ran fine driving to store but when came out the truck wouldn’t start.
Any help is appreciated. Thanks in advanced.
Regards,
Dennis

[RadCoor]

With out a code or better readings from a scanner the best I can do is a SWAG, (Scientific Wild A** Guess). I think I would look at the crank sensor. I had one go bad on a Kia. Sometimes it would start, sometimes not. That being said, I would try to locate a scanner that could read your codes and sensors. Sorry I can not be of more help.

[dennis524]

Thanks for your reply.
The Sonoma belongs to my neighbor and before I got involved he replaced the crank sensor.
The way it is acting and not being able to read the codes I think the crank sensor is very possible.
Next step will be to check if the sensor is getting voltage and go from there. My big headache is what
computer system this truck has. I can’t find any information about it.
Thanks again.

[Importech]

Hi, Instead of focusing on the computer to solve your problem, try Matt’s no start diagnostics here:

FASTTEC method link –

[Importech]

Sorry, that link didn’t work right, but follow that link and scroll down to number 25, No Start Diagnosis- FASTTEC method part 1

[dennis524]

Thanks for your reply.
I Haven’t watched that video yet but I will.
I am just wondering what OBD version the truck has it’s
made by General Motors but the pins doesn’t match either
I or II.
Not gonna give up and take it in to a service station.
Will get it figured out.
Thanks for your help.
Dennis

[dennis524]

Got an update on the Sonoma.
My neighbor went out Sunday morning to try starting the truck and
it started up fine???????????? Saturday night we did get it running but it wouldn’t
stay running unless you kept your foot on the gas pedal. So we let it run for a while
till it got hot. Next morning he came out to start the truck and it started like nothing was ever wrong
with it. No service engine light either.
We drove it about 5 miles with no problems.
I am really disappointed because we don’t know what was wrong with it in the first place.
I would not be able to trust driving it. My neighbor is happy and called it fixed.
It’s probably goin to happen again.
I forgot to mention Saturday night we replaced the EGR valve and a bad spark plug wire.
Before that all it would do is try to start and then backfire.
Hope this makes since. Thanks to all for taking the time to help.
I’m still curious about the computer on this thing.

Thanks,
Dennis

[Author]

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