This has been an ongoing problem and a royal pain in the ****. About 5 months ago, all my windows would not roll up. My mechanic diagnosed as Window Master Switch. He replaced with original OEM dealer part. It worked fine for about 3 months. Same thing happened again. Windows would not roll up. I took it back to my mechanic. He checked all fuses with some kind of electronic device. They were all fine. They decided it was a faulty master switch part. They replaced it with a new OEM part under warranty. It just failed again yesterday after about a month. I could tell something was going on. The locks kept locking and unlocking flicking back and forth while I was driving yesterday. Coming out of dunkin doughnuts, the alarm just goes off just when I am about to open the door. I did not arm the car. I put my key in the car to stop it and it would not stop. I get in the car, crank the car up and the alarm is still going off. I got out, shut the door, lock and unlock and finally went off. All other electrical works. Dash, sliding sunroof, lights, stereo etc etc.

To make matters worse, a thunder storm rolled through NJ last night. I sealed windows with garbage bags. What's going on here? Should I get some holy water and throw on the car.

 

I had similar problem with the stock master switch, I replaced with a junk yard one, it occasionally stop working, so to reset it, I just pull the switch out from the arm rest, unplug the 2 plus, then plug them back, it is working again.

 

I tried this with the 2nd oem master switch and it did not work. I went to a junkyard yesterday and got a master switch for $40. It worked for about 3 hrs and crapped out. Same thing happened, locks were flickering back n forth. Alarm went off. Put the key in door, alarm still going off. Started car, alarm still going off etc etc. What is also interesting is that in the short time that the oem and junkyard part worked, the rear door locks kept locking even when I unlock them manually. I shut my drivers side door and they automatically lock while the drivers side remained unlocked. My mechanic is stumped. I do have a modified high output alternator that was put in back in April 2015 that is only putting out 160amps which I think is only 40 more than stock amp.

Can anyone else think of something? I'm looking for a list of things to give to my mechanic to check.

 

Try putting the stock amperage alternator in and see if the problem still exists. This is fairly easy to do with basic hand tools.

 

Lux,

Thanks for the suggestion. Unfortunately, the old alternator died after 2 years of usage. It was also modified for 140 amps. Had no problems at all. It worked great. I wonder if these master switches are getting fried in some way or are they just shutting down and not working. Also, I've had alarm problems for past 2 years before issues with master switch. I just don't know if it is all connected in some way. No other electrical issues. Just too much of a coincidence and exact same thing happened yesterday. Went out to my car, open door, alarm goes off and I did not arm it when I left. Put key in door, did not go off. Put key in ignition and cranked car, did not go off, turned off car, shut door, put key in ignition and finally went off.

Can you think of anything else?

 

The amperage ouput of the alternator doesn't mean anything for this problem. But the voltage output does.

Get a voltmeter and measure the voltage while the car is running. Check the voltage at different rps, from idle to 4k, higher if you want to. The voltage should be around 14.2 volts and definitely not higher than 14.7 volts. Too high of a voltage will destroy microprocessors and the master power window switch, the BCM and ECU have microprocessors in them.

 

Have him check the driver's door wire harness. The area between the door and the body of the car is prone to having broken wires due to flexing (opening & closing door) over the years.


I've repaired a couple of these on different cars in the past.

 

Do you have a key remote? My max had similar problem loooong ago. I cleaned all the grounding points. Put new - + terminals. Bought new key fob,reprogrammed it bought new battery and problem went away. It was annoying because it would randomly go off at night and wake neighbors.