I have a 99' Tahoe, and the service engine soon light came on a while back. Then it turned off, and now its back on. So i went to autozone to have them hook up their scanner and I'm not getting any power at my obd port. Does anyone know where I might begin to troubleshoot this? Thanks

 

Do you happen to know the DTC?

 

If I had to guess I would say o2 sensor, but I don't know. I was trying to figure that outbut couldn't because there is not power at the plug.

 

That doesn't sound right, have a dealer connect a Tech-2 device and see what happens.

 

I'll bet your cigarette lighter is out too...

Same fuse. Both my 2000 and 2007 have done that... Just my guess...

 

unfortunatley my cigarette lighter is still working. It looks like all the wires are intact, and everything is working except the plug for the obd scanner. I had the people at auto zone even test the scanner on another vehicle to verify that the scanner was working. I was hoping to avoid a trip to the dealership.

 

On my 2000 Tahoe if memory serves only one of the 3 cigarette lighters didn't work. (This is memory though..) The 2007 wouldn't pass a smog test of some sort when they found that problem. I'm always plugging gobs of kids electronics into my stuff, hence my post with my past experiences.

 

thanks guvner, it was a fuse. It was the 25 amp "auxillary power" fuse. I replace it, and the error code that the scanner read was PO440, which I was told is some type of egr thing. He reset the code and it has not come back on, he told me it was probably my gas cap. Thanks for the help

 

My 2000 Tahoe's favorite error code was always blamed on the gas cap. I did replace it with an aftermarket one that didn't exactly fit in that nice holding ring inside the gas filler door but did about stop that error code from tripping my check engine light... Upon reflecting here I cannot recall seeing that same error code in the last year so I know that must have fixed it. Maybe someone else has more insight on that error with the gas cap. I never really remembered not clicking it a few times after filling up. (I think it wants to hear 3 clicks if memory serves.)