BCM question
 

Got a 2003 Eco Tec Olds N which is having a very random and seldom no start condition. The car alway cranks over however the fuel pump enable relay isn't kicking in when the car won't fire. I am strongly leaning towards a faulty BCM here's why:

1. When the car wont start the Interior lights do not function.
2. The retained power accesories malfunctions during a no start condition.
3. When cranking the car when the fuel pump doesn't kick on the SES light flashes while cranking.

My question is to those familiar with the VATS-BCM-ECM loop

Is the system like the Olds W-body which all VATS info is stored in the ECM (regarding the proper resistance) the VATS reader in the ignition switch sends the signal through the BCM and it relays the info to the ECM and sends a Crank signal and a Fuel pump engage signal? If so I think the BCM is having phantom problems. If not I need to keep looking and testing.

Does the security light flash?

No it doesnt. Surprisingly!

Have you checked the relay? If not, you can try switching the fuel pump relay with the horn relay, they're the same.

I checked the relay it seems good when I check it. I checked it by sending 12 volts through pin #85 and #86 and its clicking like it should.

In my limited experience with relays they are usually good or bad their failure isnt intermitent right?

I've seen them work intermittently, heat and moisture has alot to do with it. Just try switching them with the same model relay and see what happens.

I really dont have the luxury to do that, its not my car its a customers of mine and the no start conditon happens one time in 100 cycles. It would take me a week or more to notice if there was a change and when it fails on them again if thats not it- I look like more of a jack off than I actually am!