Power door lock issue

[Grand Prix 1965]

I have a 2002 GTP that is a 2 door and the passengers door lock will not lock with either door switch or the key fob. It however unlocks okay with either door switch and the fob. I replaced the actuator today but that didn't fix the issue. Any ideas for me?

[[ChaosweaveR]]

Sounds like a wiring issue. I'd say possibly a ground, but it wouldn't work altogether. Have the driver's side switch (Master switch) checked out. Run power directly to it, see what the voltage output is whenever "lock" and "unlock" are engaged.

[markpetersonii]

Fuse? My ranger did that but, I never did figure it out before I sold it... :/

Sent from my mind using telekinesis.

[Frosty]

Fuse? My ranger did that but, I never did figure it out before I sold it... :/

Unlikely since the power door accessory runs through only one fuse - open or closed. A bad switch would be my first guess as well. All remote keyless entry fobs require power door locks to operate. So if the switch or a ground is bad, it won't matter much. I would also run an ohm check across the switch contacts too. Inspect your connections on your switch too - they could be loose. Also check the connections on the driver side motor (which means disassembling the drive side door) and check the voltage and ohms at the door lock too. Bi-directional motors often have more than two leads.

[Grand Prix 1965]

Unlikely since the power door accessory runs through only one fuse - open or closed. A bad switch would be my first guess as well. All remote keyless entry fobs require power door locks to operate. So if the switch or a ground is bad, it won't matter much. I would also run an ohm check across the switch contacts too. Inspect your connections on your switch too - they could be loose. Also check the connections on the driver side motor (which means disassembling the drive side door) and check the voltage and ohms at the window motor too. Bi-directional motors often have more than two leads.

You mention the power windows, do I need to check these also since it is only the passemger lock that is acting up and they are on separate switches or do they share some type of power from each?

[Frosty]

I made a mistake, I meant to say the door lock not the power window. Now that said, it is possible that the power windows and power door locks could share a common ground. The driver's side door switches are the main switch for the windows and door locks. So the passenger side door goes through the main switch too - especially if there is a driver's side lock out.

[Grand Prix 1965]

I took the lock switch from each door and switched them to the other side and it still has the same issue.

[Frosty]

OK that tells me the switches themselves are probably okay. I would still do an ohm test on both switches to make sure the resistance is nearly the same. Assuming the switches are okay, then you have a relay or ground issue. You may have to physically trace the wires through the door back to the fuse block. Check where the door meets the body, make sure the wires are not getting cut or pinched. Check the fuse too. Your owners manual should be able to tell you which fuse impacts the power door locks.

[Grand Prix 1965]

I don't know much about the electrical systems on a car but I will check the switches and the wiring but if it unlocks wouldn't that rule out a fuse issue or a relay issue? I bought the car about 6 months ago and it worked then. I will check by the door wiring also, thats a good idea and easy to check.

[Frosty]

I have a 2002 GTP that is a 2 door and the passengers door lock will not lock with either door switch or the key fob. It however unlocks okay with either door switch and the fob. I replaced the actuator today but that didn't fix the issue. Any ideas for me?

OK - so if I re-read your problem, it is only a problem locking the doors, wIth or without the key fob. Unlocking works just fine. Right?

I will have to think about the electrical implications because a worst case scenario would say you have a bad BCM (body control module). Before I spend some serious cash on a replacement the BCM, I would make certain everything else in the system works the way it should. First, I would pull the door panels off and visually inspect the physical locking/unlocking mechanisms. I'd look for dirt and contamination build up near the lock or on the rods and on/near the electrical actuator. Perhaps there may need to be some WD-40 applied to the lock or rods. Try moving the rods by hand locking and unlocking the door. See if the rods move the same distance as you doing in manually.

Next I would disconnect one of the rods from the electrical actuator for the door. I would then try to lock and unlock several times. I would check to see if the actuator is pulling with enough strength to lock and unlock (each direction). I would also use my volt meter to check voltage and ohms on the actual actuator and record those measurements and then go over to the other door and do the same thing. Compare the readings. If they are close, then I suspect one of two things is going on here: either the actuator's are bad or there is something else further upstream - like the BCM

I stumbled upon this diagram in another forum. It might also help you with your diagnostics.

Accepted Answer

Ok, the snap on scan tools are good ones. but they cant read imputs or outputs. or control the door locks. normally requires a GM TECH 2 scan tool. the door locks is a fairly simple circuits. the door lock switches and the remote entry module provide imputs to the bcm simply turns on the ground side to work the doors.

For door lock operation, the IP Fuse Block supplies battery positive voltage, through theXXXXXLK/TRUNK fuse, to the BCM. The BCM uses this circuit exclusively to apply power to the door lock actuators. The BCM is also supplied a ground circuit, which it uses exclusively to ground the door lock actuators. When a door lock is pulsed, the BCM internally connects these two circuits to the appropriate lock and unlock control circuits to actuate the locking or unlocking functions.

[Grand Prix 1965]

Thanks for the diagram. The issue is that the passengers side only will not lock. I had the door panel apart and replaced the actuator with no luck. everything moves easily and is not dirty. Even without anything connected the actuator only energizes when the unlock is pressed on either door switch or the key fob. When locking the doors with either door switch or the fob only the drivers door energizes and locks.

[Grand Prix 1965]

I know that it has been a while since I posted the original post on this issue but I finally got around to getting a used BCM and took it to the dealer to install and program. The original BCM was bad so now the power door locks work great.

[Frosty]

That's great news. Did anything else also start working that was not working?