P1640

So I have this code popping up on my 95 SC Rivy. CEL constantly on. I have a new BCS on the way (the one from the Series II, my understanding is that it works, you just have to get creative with the bracket). Otherwise, it is my understanding that this code is for quad drive 1 which represents the TCC solenoid, boost control solenoid and some part of the evap system. I am having no problems with my transmission at all. While I wait for the BCS to get here, is there anything else I can do to troubleshoot? I'm going to replace all the vacuum lines today. I recently replaced the coupler in the SC and added new fluid. Also installed the new gasket, new throttle body o-rings and new throttle body gasket. New PCV valve. Code was present before and after.

No. Wait for the new BCS. No sense in chasing a ghost if the BCS ends up being the problem.

Put the new one on, and see if your code goes away. If it doesn't, you know what the problem isn't

I hope that is the problem. A lot of people on other non Riviera specific websites say most of the time it is...otherwise, it's usually the ECM/PCM. (fingers crossed)

I put the new BCS on, didn't have any problems with that. Code still present even after about 100+ miles of driving BUT one problem I had before that I don't have now is that the cruise control would randomly stop working. Now, it was on consistently during the 100ish or so miles. Not sure if that is related. Today I changed the spark plugs (ACDELCO 41-601's) and spark plug wires (ACDelco 8mm wires) to chase a hesitation problem I've been having. SES light still on. EVAP purge valve on the way.

The BCS gets pretty hot during normal operation, but cools down within an hour or so. I'm guessing this is normal?

Something else I've noticed is that my SES light is off in the mornings when it is cooler outside, and doesn't normally come on even after I do my short drive to work. In the afternoon, when it is much warmer, my SES is usually on instantly. Same code AFAIK. What would cause this situation?

Drove about 60~ miles this afternoon, SES light was on the whole time. Parked it, replaced the EVAP purge solenoid, restarted car and light was out. Will put some more miles on it and see what happens.

Update: replacing both the BCS and the purge solenoid completely fixed my P1640 problem.

Great!