When I bought my 08 H2 I noticed that a couple of the doors didn't lock or unlock on the first try. (Read: not every door would fail to actuate at the same time, maybe just 1 or 2 of them, and it was always different ones).

I had to repeatedly hit the lock/unlock button for them to work -- I could see the lock plunger slightly moving but not going up/down the full way. Even the hatch sometimes won't lock, or will not unlock with the rest. The doors themselves have actually gotten better over time, but the hatch seems to be getting worse.

Before I go and buy 5 new lock actuators, are there any tips on things to check/adjust? Is this a common failure on these? My other GM trucks of the same era haven't had this problem.

 

That is indeed an odd problem.

Not familiar with 08 wiring per-say, but for an 05 I can comment.

• The the door modules link via a Class 2 Serial Bus to the Body Control Module, so if there is any after-market equipment (radios etc) connected to the Bus, then these could potentially interfere so check an after-market stuff.
• There is a common fuse block associated with the Drivers Door Module (DDM) and Passenger Door Module (LBEC 2 and IP Fuse Block) you could be loosing voltage to these but it doesn't explain the rear hatch and other locks fail.
• There could be a problem with the DDM in that it's communicating multiple locks/unlocks due to an intermittent problem or switch (water ingress?) Check the other Lock/Unlock switches and see if the problems the same.
• Check the IP Relay Block and connectors (Left Side of Dash near Kick Panel), could be an earthing issue.
• Not sure if there are splice packs (comms) on an 08 (Can Bus) it could be an issue with those.
• Could possible be the BCM but unlikely if everything else in the vehicle works.
• There is a Rear Door 20A "Locks" fuse behind the LHS of dash, gain that's just the rear doors

It would be almost statistically impossible for multiple lock actuators to all fail at the same time and I'm sure you don't want to go down that route.

Think it would come down to three main possibilites

1. Comms problem that affects the locks (after-market, BCM, Splice Pack, Wiring)
2. Voltage problem i.e. a common voltage loss (earth or +12V) fuses, earthing, wiring. (unlikely)
3. An issue with a door module, lock/unlock switch or electronics.

I seem to recall another similar question, you can try searching this forum if you haven't already.

Please keep the forum posted, I'm sure other may chip in to help.

 

If problem is getting better over time, it could be actuators. Common problem on the H2.
And you actually see them trying to move, which is a classic actuator problem. Getting power, but too weak for full travel.
If previous owner did not use automatic door locks, they could have been stiff. Or just linkages seized (unlikely).

But like oceanbrave said, it could be other things also.
Actuators are a bear to get to, and be prepared to brake a few things getting them out.
I just did one of mine. And the back hatch actuator went out 10 years ago, when the vehicle was still new-ish. So yeah, they fail. These 08 vehicles are now a 14 model years old.

You can buy cheapo chinese actuators online, but for the amount of labor to get them in and out, I stick to the much more expensive OEM.