Power window problems

[el_brio]

Driver's window stopped working (and all windows for that matter). Replaced switch (switch was already damaged... child lock didn't work). Didn't help. Checked power @ switch... no power. Checked power @ fuse... no power.

Called GM sevice tech and he said it may be the BCM. I don't want to buy this part unless I am pretty sure that it will fix the problem. Some questions:

Is the BCM the likely culprit?
Is it necessary to reset the BCM after changing the switch?
Can I reset the BCM by disconnecting the battery and letting car sit? (How long... overnight didn't seem to do the trick)?

I already pulled the door apart and inspected the regulator. Seems OK. No burnt smell. Dissassembled it and it looks OK. Should I pull the door apart again and check the regulator motor by hooking it directly up to a current source?

Thanks!

BRian

[GTP Dad]

Welcome to AF!!

I would check the motor with a known power source to make sure that it works. As for voltage to the windows the BCM shouldn't have anything to do with the voltage to the windows and to the fuse. These are a heavy amp piece of equipment so I would check the wiring. If you need a BCM try one from a wrecking yard first to see if it helps. Just make sure to get one for a car like yours. Most generally they need to be reprogrammed by a dealer but you might get lucky.

[BNaylor]

The power windows run off a 30A circuit breaker not a fuse. Reset the breaker located at the top row of the fuse panel located at the right side of dashboard.

Is the radio working? This is important because it will determine whether you need the BCM or if just a wiring problem related to power windows only and to aid in systematic troubleshooting.

Both the radio and power windows get the 12 volts via the retained accessory power relay (RAP) when ignition is set to on. The RAP relay is energized by the BCM module. If the RAP relay is bad or not being energized both power windows and the radio will not operate. If the radio is working then the RAP is most likely good and that would rule out a BCM module and the retained accessory power. If neither radio or power windows are working then the possibilities are the RAP relay not energizing/bad or the BCM module which provides a ground/low to energize the RAP relay.

[el_brio]

Radio is working. I have a hard time believing this is a wiring problem. Wiring typically doesn't just fail.

[BNaylor]

To verify measure for 12 volts at the power window circuit breaker. From there the 12 volts goes to the driver's side window switch assembly. The 12 volts for the remainder of the power windows feeds from the driver's side switch assembly so it is the common point. Check for loose and proper connections at that switch. I think you can rule out the BCM module for now since the radio and RAP circuits appear to be working.

If the 12 volts is still missing then you may have a problem from the power window circuit breaker back to the output of the RAP relay. That is all I can think of for now.

[GTP Dad]

Boy Bob you really know your SH_T when it comes to Pontiacs and Buicks! Just thought I would give you a quick Kudo for that information.

[steven david]

F.Y.I. had power window problem on a 92 century ,front windows only on a 4 door. motors worked when switch was by-passed so i bought a new master switch (drivers side).did not help. found out that the ground for master switch went through a safety switch on the door latch that will not allow windows to work with door open. easiest fix was to strip some of the black ground wire at switch and tie in a jumper with a screw to the door

[BNaylor]

Originally Posted by steven david

F.Y.I. had power window problem on a 92 century ,front windows only on a 4 door. motors worked when switch was by-passed so i bought a new master switch (drivers side).did not help. found out that the ground for master switch went through a safety switch on the door latch that will not allow windows to work with door open. easiest fix was to strip some of the black ground wire at switch and tie in a jumper with a screw to the door

The systems between older '92 Century and '97 and up are different. Superceded by the body control module and retained accessory power circuits. Your '92 does not have a BCM module.

On '97 and up Century the power windows will work with the door open as long as ignition is on and RAP has not kicked in/expired (either after 10 minutes or when driver exits with key out of ignition) so your suggestion doesn't sound relevant or applicable. The door switch is a magnetic sensor type and the same one is used for the courtesy lamp illumination when opening the door, remote-RKE/power door locks, door warning/ajar, RAP and other body control module (BCM) functions that use the door sensor.

[el_brio]

OK. So there is NO power at the circuit breaker. I did notice that the power seats (same type of circuit breaker and same location) is only registering current when I operate the switch. Does this seems righ? Based on this, if the circuit breaker doesn't register current it could still be the switch... or the motor in the regulator. I think that tracing the leads from the fuse box to BCM is going to be a bit P.I.T.A. and sounds like an unfruitful search. Any other ideas?

[BNaylor]

It sounds like you are referring to a possible short in the circuit which is a possibility. A shorted motor or switch can load down the circuit. I would remove one side of the power window circuit beaker to isolate it from the rest of the circuit and then measure the 12 volts. Also, remove both leads to make sure the breaker is good by ohming it out. If good then the short is after the circuit breaker. If 12 volts is not present then back track to the RAP relay and before that the BCM module. The RAP relay is one of the 3 or 4 relays located on that bank of relays right behind the glovebox. It is better to remove the glovebox to access it and the relay socket. But if the radio is working (getting power) then the BCM is probably good since both power windows and radio receive 12 volts via the contacts of the RAP relay according to the GM FSM wiring diagrams.