Service engine light

[grs]

Will driving the 87 today the service engine light came on. I was going 65 miles per. If the cat is bad would the light come on? After I turned the engine off, and back on the light went off. I have a tool to check it with, but I forget how to do it.

[Stepper86]

I have a similar problem, mine stays off most of the time. If I accelerate hard it comes on, or if I leave the truck to idel for a while and then rev it up a bit. I don´t have a test tool, and I have not had time to flash the varning codes on the truck.
But my 92 Covette acted similar to this when I bought it, turned out to be the Co2 sensor, so I hope that it´s as easy as that.

[grs]

Originally Posted by Stepper86

I have a similar problem, mine stays off most of the time. If I accelerate hard it comes on, or if I leave the truck to idel for a while and then rev it up a bit. I don´t have a test tool, and I have not had time to flash the varning codes on the truck.
But my 92 Covette acted similar to this when I bought it, turned out to be the Co2 sensor, so I hope that it´s as easy as that.

I have the little forked looking tool that goes in the plug in thing under the dash. I just have to remember how to use it to check the flashes on the dash.

[Stepper86]

If I remember correct you put it over the 2 pins in the upper right corner of the OBD connector (B,A)

[grs]

Originally Posted by Stepper86

If I remember correct you put it over the 2 pins in the upper right corner of the OBD connector (B,A)

I had a small book on how to do it, but I think I threw it away. I will check Auto Zone to see if they have one.

[Stepper86]

Here is a link that might be helpfull. I used it when I pulled codes from the Vette.

http://www.troublecodes.net/GM/

[grs]

Originally Posted by Stepper86

Here is a link that might be helpfull. I used it when I pulled codes from the Vette.

http://www.troublecodes.net/GM/

Thanks that is what I needed. Now I have all winter to do it.

[grs]

Originally Posted by Stepper86

Here is a link that might be helpfull. I used it when I pulled codes from the Vette.

http://www.troublecodes.net/GM/

I checked the code today. It was a code 12. That means there is nothing wrong I think.

[Jonboy]

Code 12 is actually no distributor pulse. When you short the pins, you put the ECM in field service mode. It should be done with the key on, engine off, hence no distributor pulse. the code 12 also serves as an "all clear" of sorts. The codes will start and end with 12.

[Weasel Diesel]

It flashes 12 three times, then the codes, then ends with three 12's Each code flashes 3 times before moving to the next. If the light goes out after you shutoff & restart the truck, it is a soft code like an o2 sensor, ect. Be noted... Ethanol enriched fuels love to reek havok on old style o2 sensors.

[grs]

Originally Posted by Weasel Diesel

It flashes 12 three times, then the codes, then ends with three 12's Each code flashes 3 times before moving to the next. If the light goes out after you shutoff & restart the truck, it is a soft code like an o2 sensor, ect. Be noted... Ethanol enriched fuels love to reek havok on old style o2 sensors.

Thanks, I will drive it and see if the service engine light comes back on. Does anyone make a better O2 sensor for these trucks?

[grs]

Originally Posted by Weasel Diesel

It flashes 12 three times, then the codes, then ends with three 12's Each code flashes 3 times before moving to the next. If the light goes out after you shutoff & restart the truck, it is a soft code like an o2 sensor, ect. Be noted... Ethanol enriched fuels love to reek havok on old style o2 sensors.

The light came on again. I got a code 32. It could be the MAP sensor is open,or the EGR circuit is bad. Where is the MAP sensor located? And what does it mean, it could be open? And I am getting 19 MPG on the road.