no obd2 reading need help

[rpm4kt]

Im tring to work on my wifes 97 grand am with the 3.1. The car will start some times. Some times i have to help it with the acelerator and keep it running or it will just go to nothing. Sounds like a MAF scensor but here is were it gets weird. I plug in the obd2 reader and it doesnt work nothing comes on the screen it doesnt turn on or anything. I tried it on my car and worked perfect so i know its not the reader. If anybody can help me i would realy be greatful. thanx RPM

[J-Ri]

Check for power and ground to the connector. Make sure none of the wires under the dash are broken or chewed through.

[rpm4kt]

thanx for the advice i pulled the bottom dash peice off everything looks ok but didnt think to look for power going to the plug. have to check that out too. do you have any idea where the pcm is on that car??? thanx RPM

[rodfoster]

hi i remember when i worked at the GM dealer somebody told me about the OBD receptacle needing power from the cig lighter fuse-i would check that next!

[J-Ri]

That is true on almost all OBD-I vehicles, but OBD-II has power to the connector.

I believe the PCM is back behind and below the glove box... there's lots-a wires going into something shiney and metal, just don't know for sure it's the PCM.

[rpm4kt]

Thanx for the reply ill chaeck it out but i think that is the body modual most gm models have it under the hood just cant find it lol. but something else to look at i guess.

[xeroinfinity]

What type of scann tool are you using RPM ??

I'd drop the kick panel on the drivers side, and look at the wires going to the ODB connetor.
You could have a wire loose or damaged, even as mentioned above if a fuse is blown for this circuit.

Here is the pinouts for the OBD 2, bottom 16 pin connector..


The pins are used in the following way:
Pin 2 - J1850 Bus+
Pin 4 - Chassis Ground
Pin 5 - Signal Ground
Pin 6 - CAN High (J-2284)
Pin 7 - ISO 9141-2 K Line and ISO/ DIS 14230-4
Pin 10 - J1850 Bus
Pin 14 - CAN Low (J-2284)
Pin 15 - ISO 9141-2 L Line and ISO/ DIS 14230-4
Pin 16 - Battery Power

[rpm4kt]

i got it finaly lol.its wired through the horn relay just in case anyone is haveing the same prob thanx for every ones help. but now haveing the same prob with the idel has extreem high ideal when starting. i replaced the idel air control motor and helped for about a min now kicking code for low input on pedal position scensor. now is that the same as the tps ?? and or does the map scensor contol the output on that ????

[xeroinfinity]

High idle could be many things other then the IAC.
Could have a dirty IAC port, could have a vacum leak...

What Codes EXACTLY did it show ?

[rpm4kt]

i want to say P0122 pedal position scensor. id have to check again to make sure . I was reading a book and it said something about the MAP controlling air fule mix and scensor input or voltage. ill have to doubel check.