Hey guys, I am in need of some direction. I am working on a 2000 (i believe) grand prix se. The complaint is that when the car was taken to emissions it failed due to their scanner machine not being able to establish a connection with the vehicle. It will also not connect to my scanner. I have the wiring diagram for the diagnostic port. I have checked for power and both grounds, it has both. I have went through all the fuses and they were all checked with a meter and appear to be in good operating condition. I am hoping you guys have some suggestions before I have to start tracing wires.
I believe this to be an electrical issue at the moment. I have read that aftermarket things such as radio and alarm can interfere with the diagnostic port if hooked up incorrectly. I have tried scanning with the radio harness unplugged by the way with no luck. The car appears to have a few wires spliced into the ignition circuit including a flashing LED but I cannot see an aftermarket alarm module. The car does have factory keyless entry.
You can view the wiring diagram here: EBSCOhost Login
NOTE:: Some things I have noticed are wrong with the vehicle.. Underneath the dash there are wires spliced together. white and pinkish. I was told this was done by a few owners ago to bypass the car not being able to shift from park. (idiots...) The switch on the drivers door will unlock all doors but not lock them. The chime stays on all the time unless the key is in the on position or the doors are closed. Kinda like the lights were left on, nothing appears to have been left on.
I am racking my brain on this one and am trying to help a friend, if this issue could be related to those spliced wires I will not be getting into this as there is no telling what could have shorted out. Thank you for any help you guys can provide.
