A quick question to see if anyone knows what to do.....

I have an 03 GMC 2500 crew cab.

My stock remote will turn on the alarm, lock / unlock the front doors, unlock the back doors but will not lock the back doors.

Its driving me crazy. My kids open the rear doors when the doors are supposed to be locked and end up setting off the alarm.

Does anyone know what I can do to get the remote to lock all four doors?

Thanks!

Ross

It has to be a wiring problem. There is only one lock relay (at least on the 01 and 02's.) When you hit any lock button it should lock all the doors.

On second thought, if the handle linkage wasn't working right, it may cause the lock mechanism to jam. I would check for crayons in the rear door handles.

03 and up use driver and passenger door control modules in the front (built into switch assembly). Unfortunately, check for DDM or PDM codes first. It could very well be a wiring problem, though, check a schematic for a wire that feeds both rear doors before a splice to go to individual door.

In the fuse panel by the drivers door there are 2 relays for lock and unlock. Try swapping them and see if the problem moves to the rear doors not unlocking. Most likely it's just a bad relay. You wouldn't be the first to have problems with it.

:exactly: as stated by MaxPower.

Yea, what Max said, and the relay is a dealer only item.

Yeh it's a relay. Had this problem before. Took it to a dealer that said it was the door locks. I told him how is that, when i change these relays it reverses the problem? He didn't know, but it was going to be like $600 to fix what he thought was the problem. I walked away laughing. Take the relay out and tap it firmly into your hand. This would free mine up for several days.

If you know someone with a Tech 2 you can check it that way. BODY--->DDM--->OUTPUT CONTROLS--->REAR DOORS

you can command the rear left and rear right doors to lock independantly with a Tech 2 to check the relay, and the DDM function...and check DDM and PDM data/inputs as well...

I love the 2003+ trucks :D

I think its so cool how integrated everything is.

Thanks for all of the advice.

I think I will begin with the relay and then go from there.

Learn something new everyday!

I will let you know how it goes.

You guys are right on the money!

I started looking at the relays. I tried to pull one and it was harder to pull out than I thought so I pushed it back in. I chickened out!

I then tried the remote and the locks started working. Looks like I just had to wiggle it a bit to make a better connection.

Thanks again for the advice.

If you know someone with a Tech 2 you can check it that way. BODY--->DDM--->OUTPUT CONTROLS--->REAR DOORS

you can command the rear left and rear right doors to lock independantly with a Tech 2 to check the relay, and the DDM function...and check DDM and PDM data/inputs as well...

I love the 2003+ trucks :D

I think its so cool how integrated everything is.

Tell you I am starting to hate how everything is run by a computer in these trucks.. Dam computers!!! Codes all the time in the winter and now a low coolant msg even when the coolant is full.. Dam computer bull... Funny part about it is I am a programmer by trade.. LOL