Power Door Locks

The power door locks on my '99 Tahoe do not always work. Most of the time they all operate except for the front passenger door. It attempts to move, maybe halfway, but doesn't lock or unlock all the way. It works fine manually. The keyfob works the same way as the door switch. About 10% of the time they all work fine incuding the passenger door.

I've been told they might not be getting enough voltage due to loose connections. The connections look good as far as I can tell. What should I look for on my multimeter and where should I test it?

Is there something else I should look at?

they have alot of problems with door lock actuators in these vehicles, they get weak, check these first. hope this helps

This will really be no help, but I have exactly the same problem...

Where are the actuators and how do I check them?

The power door locks on my '99 Tahoe do not always work. Most of the time they all operate except for the front passenger door. It attempts to move, maybe halfway, but doesn't lock or unlock all the way. It works fine manually. The keyfob works the same way as the door switch. About 10% of the time they all work fine incuding the passenger door.

I've been told they might not be getting enough voltage due to loose connections. The connections look good as far as I can tell. What should I look for on my multimeter and where should I test it?

Is there something else I should look at?

I have a 99 Tahoe Z71 model and it is doing the same exact thing. My front passenger door does not work all the time. Have you noticed that in cold weather it works, but in the heat it doesn't. My lock will work most of the winter, early in the morning in summer, and that's about it. Let me know what you find out about this. Jason Cooley [email protected]

I have a 99 Tahoe Z71 model and it is doing the same exact thing. My front passenger door does not work all the time. Have you noticed that in cold weather it works, but in the heat it doesn't. My lock will work most of the winter, early in the morning in summer, and that's about it. Let me know what you find out about this. Jason Cooley [email protected]


I purchased my '99 Tahoe used in May so I haven't had it in cold weather yet. Of course everything worked fine when I bought it. Now I'm having problems with the cargo door locks in addition to the passenger door.

Same problem with my 2000ltd (old body style). Front passenger door first, then rear passenger, and cargo barn doors in that order. Also, my lock switch on the drivers side door/armrest seems to be failing as well. Bad connection or corrosion or something. And yes, heat seams to be a factor as well. In Sacramento we get into the triple digets and the a actuators just hate it. I'm thinking about taking everything apart and cleaning/lubricating the switch and the acuators. Anybody tried this? Would it even help? Or do I need to get new stuff like the other posts have suggested?

I don't see any answers accept possibly the actuators, DOES ANYBODY KNOW? What is the problem and how can it be fixed?

I have a 99 Tahoe Z71 model and it is doing the same exact thing. My front passenger door does not work all the time. Have you noticed that in cold weather it works, but in the heat it doesn't. My lock will work most of the winter, early in the morning in summer, and that's about it. Let me know what you find out about this. Jason Cooley [email protected]

Since its gotten colder it will unlock but not lock. Still a pain. I ordered an acuator. I'll let you all know if it fixes the problem. I'm going to clean and lube the old one before I repace it. Just to see if that works.

Would an actuator effect the rear hatch button at the same time? Both front buttons and the rear hatch button all went at the same time.

good chance it is the actuator each door has one chances of all going are slim.pull door panel hook switch back up and operate you will see rod going ito plunger attached to actuator 2 rivets and plug if it seems week you can move rod manually if easy and actuator doesnt move the rod fully most likely problem

I have a 95 Tahoe and the auto door locks do not work when it is warm outside but do when it is cold. A similar situation happened on my wife's audi where her electrical fuel pump would not work when hot but would when it was cold. Turned out to be a relay as a metal curcuit in the relay would touch when cold which completed the curcuit but the metal would expand and not touch when warm. Anybody know the real deal with the Tahoe power locks?

Same problem with my '99 tahoe ... only happens on the passenger side mechanism and only when it gets hot. I am thinking that one of the components is expanding out of tolerance when it gets hot, causing the the mechanism to stick. I can't prove it just yet though ... I'll need to wait until June/July again.

I replaced the door lock actuator. That fixed it. Now the actuators in the rear cargo door and the passenger door are failing By the time I replace those I'm sure the rear passenger doors will be next.

However, in the process I screwed up the door latch. It appears the rod that moves the door lock mechanism came loose and does not operate the mechanism when the outside door handle is used. The inside handle works fine. I can barely get my hand inside the door to reach it. Plus I'm flying blind. I don't know what it looks like and I can't find a diagram on the web. My Haynes manual doesn't have show it either. Does anyone know how to get that rod back where its supposed to be?

Thanks.

I pulled my 2dr 99's apart a while back and clean and lubed the moving parts, the thing to watch for is the rails that bend very easy and end up needing to be replaced if you do, Ive seen it before, so i took extra caution with them, so far the lube works, but im looking into new actuators just in case.

jd

Hey Droos,

I've got a '99 two door too. Let me tell you what I've done and see if you can help me, I'd greatfully appreciate it.

I recently bought the Tahoe. I checked out the keyless, electric locks, windows, etc. Everything worked fine. I decided to buy it, the next day when I picked it up and the keyless/doorlock buttons stopped working.

The locks budge but not lock or unlock action. It doesn't matter if it's from the keyless fob or the button on any of the doors. Sounds like the same issue you had.

I've put in a new relay, no good. You are the first person I've heard of saying an Actuator fixed their problem.

Here's where I need your help.

How do I determine which Actuator is not working properly?

If I were to check them, would I stick a voltage regulator to it or something?

Where and how much did you purchase the Actuator for?

Like I said, I would greatfully appreciate your help.

Thanks.
WorleyGuy
[email protected]

Hey Droos,

I've got a '99 two door too. Let me tell you what I've done and see if you can help me, I'd greatfully appreciate it.

I recently bought the Tahoe. I checked out the keyless, electric locks, windows, etc. Everything worked fine. I decided to buy it, the next day when I picked it up and the keyless/doorlock buttons stopped working.

The locks budge but not lock or unlock action. It doesn't matter if it's from the keyless fob or the button on any of the doors. Sounds like the same issue you had.

I've put in a new relay, no good. You are the first person I've heard of saying an Actuator fixed their problem.

Here's where I need your help.

How do I determine which Actuator is not working properly?

If I were to check them, would I stick a voltage regulator to it or something?

Where and how much did you purchase the Actuator for?

Like I said, I would greatfully appreciate your help.

Thanks.
WorleyGuy
[email protected]

At the time I replaced the actuator only the driver's door was causing a problem. There is one actuator per door so it was easy to determine which one was not working.

I did not test mine. I didn't know how. When I disconnected the actuator from the door lock mechanism I did try it while the wires were still connected. It worked fine. I guess it couldn't handle the load.

I bought it for about $35 on the web. I don't remember who I bought it from. I'll send you their name if I do.

I am still having problems with two doors. The passenger door doesn't work when it's hot & humid and it is hot & humid most of the time in South Carolina. My cargo door power lock doesn't work at all. I guess I'll replace that actuator soon.

Good luck.

I have been having door lock problems with the rear hatch and both back doors. The dealer told me the acturators needed to be replaced. This i find hard to believe. Both rear doors function exactly the same way. They either both lock or unlock together. The hatch follows the same pattern. If it was the acturators they would not follow a pattern but would be random. It seems to be a heat related problem. When it is cold, they all work, When I run the air conditioner and keep the cab cool they work. I can't say this will continue as the summer gets hotter since I purchsed the truck in the middle of the winter.

Has anyone else had this heat related issue and if so, what was the FIX.

Thanks
Bdee

Follow up on Rear doors and hatch not locking on 2004 tahoe. I thought I had this fixed by resetting the lock/unlock relays but it has failed again. I pulled the panels from the hatch and rear doors and found that no power was being sent the the actuators. I found white pages on power door locks description and operation so now I know how it should work. When you press LOCK on the keyless it sends a signal to the PDM (passenger door module) which locks the pasenger door, sends a signal to the DDM (drivers door module) which locks the drivers door. The PDM also sends a signal to the BCM (body control module) indicating a change in locking mode. The BCM then sends power to the LOCK RELAY which routes power to the rear passenger doors and the rear hatch lock actuators. At this time I found that if I reseat the UNLOCK Relay the rear doors and hatch will lock for a few times and then fail again. Confusing at least. Then I found that the lock/unlock relays are both normally grounded when at rest and when the BCM sends power to the LOCK relay the relay is put into OPEN mode and power goes to the door actuators and then the LOCK relay returns to closed mode. The same thing happens when you press unlock (twice) on the remote. The BCM sends the power to the UNLOCK Relay which opens and power is sent to the lock actuators, reversing polarity and unlocking the doors. What this means is the actuators are grounded AT the LOCK/UNLOCK relays. By reseating the UNLOCK RELAY I have re-established ground for the locking function. I don't think the problem is with the Lock/unlock relays since swapping them I still have the "will not lock" issue so I'm inclined to believe the problem is in the wiring connections in the Fuse block holding the unlock relay. AND I still don't beleive the dealer is right in saying the lock actuators need replacing.