This 2000 Pontiac Sunfire had multiple dash problems. among which were most warning lights on, erratic gauge operation,the odometer read the word Error and sometimes the engine would not start. My first thought was a faulty instrument cluster because that was where all of the problems were centered.
A feeling is not good enough so I set about doing some testing. I wanted to check codes and data but I found that there was no communication with any module in the vehicle.
After looking through wiring diagrams I realized that the BCM was the hub for communication for all of the modules in the car. The BCM is located under the driver’s side of the dash at the left kick panel area.
I strongly recommend looking at wiring diagrams and component locators before doing any of these tests. It also requires a familiarity with terminal removal and safe testing practices. with live wiring and computer modules.
The purple connector at the BCM in this car is the C1 connector and the communication line between the BCM and the Radio is on terminal B8.
To make testing and identification easier I wanted to remove the terminal locking comb. There are locking hooks on either end of the retainer. Once unhooked the retainer can easily be removed.
I used a special terminal release tool to unlock the terminal and pull it from the connector.
I also went to the C2 Connector, light blue and removed the locking comb retainers.
With the retainers removed it was much easier to see the terminal designations on the plastic connector body. All wiring involved in testing the computer data lines are purple wires.
Terminal B7 connects to terminal 2 of the DCL
Terminal B8 connects to terminal 59 in the C1 connector at the PCM
Terminal B9 connects to terminal “L” of the IPC
The SRS and EBCM are linked to the communication lines through the IPC and the PCM respectively.
In testing I connected terminal B7 to terminals B8 & B9 of connector C2. Communication was restored to all modules. This only left a test between terminal B7 of the C2 connector to terminal B8 of the C1 connector. This test did not restore communication to the radio.
I needed to confirm that the problem was either in the radio or in the wiring between the radio and the BCM. With the glove box opened the two screws at the right side of the center dash panel could be removed.
It was much easier to remove the lower screw by unhooking the right side hinge stop on the glove box door.
Once the two screws were removed the center panel will slide to the right and can be manipulated off of the dash. There is supposed to be a plastic peg at the left side of the panel, but it appears that someone else has been here, because the plastic peg has been replaced by a screw.
With the trim panel removed I went about removing the screws that held the Radio in place. Phillips headed screws, more evidence that someone else has already been here.
And there it is! I had already discovered that the Radio did not work either and this is the obvious reason why. A little bit of tape on the exposed wiring.
Communication has been restored to all modules.
I did a class 2 DTC check, found and cleared all trouble codes, then started and ran the engine.
No more problems except for the obvious missing Radio.
Can you believe 237,000 miles on this little Pontiac?
There are ad links for both Mitchell and AllData on the side bars of my site. You may purchase repair information from either and both have wiring diagrams. The orange wire that you disconnected from your BCM would be a battery supply wire to the BCM. Without high end scan tool capability, I would concentrate on disconnecting the other modules on the fuse circuit. If the drain does not go away, then you will need to disconnect the data lines from the BCM to see if something else is keeping it awake. Also remember that you should allow one hour with the vehicle undisturbed to see if all modules go to sleep properly.
Sparky,
Do you happen to know any website that I can download a schematic diagram for my car (2002 pontiac sunfire). I disconnect the connector (blue, in the middle) on the BCM module and do the continuity test. I found an orange cable (i think this is a positive constant power) that is shorted to ground. If I remove that cable from the connector and plug in back the connector to the BCM, the voltage drops to “zero” on the CLUSTER fuse. Now, still the Radio, Keyless and Illuminated entry doesn’t work. Also the engine will start but it will stall after a second or two. I think, fuel is not pumping if the orange wire is remove from the BCM. ALso “Error” will display on the cluster gauge. Hope you can help. Thanks.