'05 Crew Cab Rear Doors Lock/unlock Problem

rkf63k10 · August 6, 2008

Have a '05 GMC Crew Cab 2wd, 5.3l. When I try to unlock the truck the rear doors sometimes will not unlock. They will lock just fine but, every now and then they will not unlock. It doesn't matter if I use the key remote, front door switches or when I put it in park. I was thinking that it could be the relays to the rear doors. Any suggestions on what I should look for? I have low miles on it but my warranty is up.

minibike132 · August 8, 2008

If you have option code YE9 probably the unlock relay in the IP fuse compartment. If you don't have YE9 disregard that because it will not be the problem.

rkf63k10 · August 8, 2008

If you have option code YE9 probably the unlock relay in the IP fuse compartment. If you don't have YE9 disregard that because it will not be the problem.

Not sure if I have that option or not. Where do I look? I also noticed that if I lock/unlock with the D/S door switch alot, all door lock/unlock start to get "weak" and eventually stop. Then I wait a few seconds and they start working again.

minibike132 · August 8, 2008

Post your vin# and I can tell you. Or locate the RPO label (probably in the glove box). It looks like THIS CLICK HERE.

rkf63k10 · August 8, 2008

Post your vin# and I can tell you. Or locate the RPO label (probably in the glove box). It looks like THIS CLICK HERE.

2GTEC13T651203706

minibike132 · August 8, 2008

You do have YE9, the symptom you describe sounds like the relay. The cheapest (free) and easiest way for you to diagnose it without any tools is to switch around the lock and unlock relays if they are the same and see if the problem reverses itself to not locking as opposed to not unlocking. If it does reverse you know you need a relay and you can go spend the money on one.

EDIT: That is the IP fuse block located in the driverside dash panel. Swap the relays marked Lock and Unlock, they only control the rear doors thats why I would go there first. The front doors are controlled by the bcm instead of these relays if your wondering why it is not happening to the front doors.

rkf63k10 · August 8, 2008

Thanks sparkstech i'll try that. By the way what is the YE9 option code.

minibike132 · August 8, 2008

I don't know what all is involved in that RPO, the description is SLE/SLT decor. I just needed the RPO because there is a difference in the wiring diagrams.

steingang2 · August 10, 2008

I had the same problem on my 06 crew cab. I thought there was a fuse to lock it and a separate fuse to unlock it, there seems to be a specialty fuse for everything else. WRONG, I took it to the dealership and it turned out to be a faulty wire harness connection. It took the GM electrical expert a while to track it down but that was tghe problem, a bad wire harness.

minibike132 · August 11, 2008

I had the same problem on my 06 crew cab. I thought there was a fuse to lock it and a separate fuse to unlock it, there seems to be a specialty fuse for everything else. WRONG, I took it to the dealership and it turned out to be a faulty wire harness connection. It took the GM electrical expert a while to track it down but that was tghe problem, a bad wire harness.

There is only one fuse but on his particular vehicle there are 2 different relays. A harness is a possibility but I have seen the relays do exactly what he describes. We are just trying to check out the cheap and easy before spending real diagnostic dollars, and I am a real GM electrical expert, or at least thats what they pay me to be.