ECM To OBDII Connection

**lstexan** · 01-30-2010

I recently bought a 98 GTP and the engine is running really rough, the SES light comes on and flashes sometimes. I plug in my OBDII scanner but it will not connect to the cars computer. The scanner will not even power up.
I have checked the fuse in the glove box, it's okay, I recently bought a new ECM, still not connecting.

Any other places to check?

Thanks for your help.

**FoSHO99** · 01-30-2010

SES flashing means there is a bad misfire. Check wires/plugs/coils

**TheOtherNick** · 01-30-2010

Grand prix's do not have power at the obdII port. Check and see if your scanner has a dead battery in it.

**shawn3091** · 01-30-2010

yes there is power at the obd port on a grand prix, mine has it anyways along with 2 grounds. i think it is tied into the cig lighter fuse

**TheOtherNick** · 01-30-2010

No power to run the scan tool. They do not have that. That is why you have to run a power wire to an aeroforce etc.

**lstexan** · 01-31-2010

I was told that the plugs and wires were most likely the cause for it running rough at idle, it smooths out at higher rpm. I will replace them.

The power to the ecm port being tid into the cig lighter fuse is a possibility because that fuse blows. I will have to follow up on why that happens.
Thanks for the advice and I'll get back.

**JoshMcMadMac** · 01-31-2010

Originally Posted by 01GTP

No power to run the scan tool. They do not have that. That is why you have to run a power wire to an aeroforce etc.

It powers my scan tool, and the LED lights up on my HPTuners MPVI when I plug it into the OBDII port.

**FoSHO99** · 01-31-2010

It's 01+ that do not have the power pinout on the OBD2 port.

**lstexan** · 01-31-2010

It was the cig lighter, it shorted out somehow. I have disconnected it, no smokers in mt car - ha ha, now I can connect to car's computer. I got a PO 0303 code - #3 cylinder misfire.
Thanks for all the great advice.

**minichopper6hp** · 01-31-2010

Probably a wire. Yea its ran off the cig lighter fuse as you found out.

**TheOtherNick** · 01-31-2010

Originally Posted by FoSHO99

It's 01+ that do not have the power pinout on the OBD2 port.

There we go. Coulda swore it was all of them.

**shawn3091** · 01-31-2010

Originally Posted by lstexan

It was the cig lighter, it shorted out somehow. I have disconnected it, no smokers in mt car - ha ha, now I can connect to car's computer. I got a PO 0303 code - #3 cylinder misfire.
Thanks for all the great advice.

i thought it was linked