Power Door Lock Problems! Weird Problem...

**2000TransAm400HP** · 07-07-2007, 08:30 PM

Ok. I always have weird problems that are probably solved easily but for me can be brain teasers. I have always simply used deductive reasoning to fix almost every problem I have. I may not know everything about cars but I have worked on them quite a bit and have a pretty good mechanical ability. I have a problem that is tricking me a bit. The drivers side door will lock but will not unlock. I have actually gone all the way down to taking the little motor out of the door and testing it on the other side. When switching the motor to the other side it works to unlock and lock the passenger side door so I know the motor is good. I also switched the switches and they both work on the passenger side but on the drivers side both of them wont unlock the drivers side door. So I know its not a switch and its not the motor. We tried testing the connections for continuity and dc voltage and they both seem fine. The next part of this journey involved me pulling out the Body Control Module. That is where all the relays are. When you click the unlock or lock you can hear the relays clicking normally but they are sealed units and I dont want to attempt to rip them off the circuit board. So I am pretty stumped as to what is causing the problem. I am at this point assuming that the problem is in the Body Control Module or somewhere inbetween on the wiring. The previous owner was a real piece of work so im not sure if when he did some installation work on the car he may have inadvertantly done something. I dont expect that anyone in here has ever had this problem but who knows.....

**Orcus79** · 07-07-2007, 11:53 PM

it almost sounds like a broken wire to me, will the doors lock and unlock from the passesnger side? with the switch in check for voltage from the switch to the locking motor, also check all connections to be sure theya re tight and secure. did you check continutiy across the the harness that runs between the doors?

**02z28ls1** · 07-08-2007, 05:40 AM

You didn't put the passenger side motor in the driver's side and test that. It could still be a weak motor or a binding in the locking linkage or mechanism. It works in a weakened state on the passenger side (maybe) because it's easier to move the locking linkage or mechanism there. Just a theory, sounds like you've checked everything else out.

**2000TransAm400HP** · 07-08-2007, 09:04 AM

Definitely not a binding in the locking linkage. The motor from the passenger side was tested on the drivers side and it doesnt unlock but will lock. When you press the unlock button on the drivers side you can hear the relay from the Body Control Module clicking like normal but nothing happens. No turning of the motor at all. Remember that I took the little motor out of the entire locking mechanism on the drivers side. I also did it to the passenger side also. So at this point I had the plug from the harness connected directly into the motor which bypassed all mechanical locking mechanisms. I went pretty deep into troubleshooting this. I think that it may be a connection and I need to do a better job with the multimeter. I cant say for sure that I have definitively tested all aspects of the circuit. I will post results on here as I get them.

**B34M3R** · 07-10-2007, 04:25 AM

I've got a few ideas... Heres a silly, but not entirely impossible one... could the lock button be faulty, and is shorting to the unlock side? So, even when you hit lock, its trying to unlock? It would explain the relay clicking... still isnt very likely though...

Otherwise, the fact that the relay activates, but the motor does not, means that the switch is perfectly fine, and the relay is *probably* fine. It might not be, even though it clicks... it will click if the 2 wires that control the opening and the closing are fine, but might not be making an actual connection on the inside.

Now, I don't know how the f-body power locks work, but usally the lock motors will just use 2 wires, a power and ground that alternate(with the relay) to alternate the direction the motor works... if that is in fact the way yours are, then a wire IS NOT the problem, it would have to be the relay. If it uses a 3(or 4) wire setup, then the problem would have to be with the wiring, or, of course, the relay.

That really sucks that the relay is soldered in...

Can you get a multimeter lead to the relay connections? If so, test for power and ground on each prong, and what each one of the prongs is doing when the lock and unlock buttons are pressed... as well as which are your constants... if you don't find TWO that change when you hit lock, then its the relay. I'm pretty sure on the last bit of info, but not 100%, because I'm not familar with the particular setup of relays in your car... thats a pretty standard rule of thumb to go by with that type of relay though.

Well, hope I helped some.

**2000TransAm400HP** · 07-10-2007, 09:31 AM

That is good advise. I agree with you 100%. I really do think it is a relay. Im going to do alot more testing on the electrical connections as soon as I get my new Harmonic Balancer in and get power back to my car. I will post in here when I find out what the problem was....

**0rion** · 07-11-2007, 08:18 PM

Originally Posted by B34M3R

I've got a few ideas... Heres a silly, but not entirely impossible one... could the lock button be faulty, and is shorting to the unlock side? So, even when you hit lock, its trying to unlock? It would explain the relay clicking... still isnt very likely though...

Otherwise, the fact that the relay activates, but the motor does not, means that the switch is perfectly fine, and the relay is *probably* fine. It might not be, even though it clicks... it will click if the 2 wires that control the opening and the closing are fine, but might not be making an actual connection on the inside.

Now, I don't know how the f-body power locks work, but usally the lock motors will just use 2 wires, a power and ground that alternate(with the relay) to alternate the direction the motor works... if that is in fact the way yours are, then a wire IS NOT the problem, it would have to be the relay. If it uses a 3(or 4) wire setup, then the problem would have to be with the wiring, or, of course, the relay.

That really sucks that the relay is soldered in...

Can you get a multimeter lead to the relay connections? If so, test for power and ground on each prong, and what each one of the prongs is doing when the lock and unlock buttons are pressed... as well as which are your constants... if you don't find TWO that change when you hit lock, then its the relay. I'm pretty sure on the last bit of info, but not 100%, because I'm not familar with the particular setup of relays in your car... thats a pretty standard rule of thumb to go by with that type of relay though.

Well, hope I helped some.

good post

**35thAnniZ28** · 07-11-2007, 11:04 PM

Originally Posted by B34M3R

I've got a few ideas... Heres a silly, but not entirely impossible one... could the lock button be faulty, and is shorting to the unlock side? So, even when you hit lock, its trying to unlock? It would explain the relay clicking... still isnt very likely though...

Otherwise, the fact that the relay activates, but the motor does not, means that the switch is perfectly fine, and the relay is *probably* fine. It might not be, even though it clicks... it will click if the 2 wires that control the opening and the closing are fine, but might not be making an actual connection on the inside.

Now, I don't know how the f-body power locks work, but usally the lock motors will just use 2 wires, a power and ground that alternate(with the relay) to alternate the direction the motor works... if that is in fact the way yours are, then a wire IS NOT the problem, it would have to be the relay. If it uses a 3(or 4) wire setup, then the problem would have to be with the wiring, or, of course, the relay.

That really sucks that the relay is soldered in...

Can you get a multimeter lead to the relay connections? If so, test for power and ground on each prong, and what each one of the prongs is doing when the lock and unlock buttons are pressed... as well as which are your constants... if you don't find TWO that change when you hit lock, then its the relay. I'm pretty sure on the last bit of info, but not 100%, because I'm not familar with the particular setup of relays in your car... thats a pretty standard rule of thumb to go by with that type of relay though.

Well, hope I helped some.

it might be faulty..my window button was..replaced it..problem fixed...though it was 30 bux..oh well

**B34M3R** · 07-16-2007, 10:25 PM

Please do respond when you figure it out, because I'm rather curious... its a strange problem.

Oh, and thanks guys, I try to be helpful with what I know about