Rear door locks unlock automatically, but don't lock automatically

[dewfpo]

2005, 2500HD, CCSB

The rear door locks unlock fine by the switch or automatically (when I put the truck in park), but they don't automatically lock when I hit the lock button on the door or the remote, or when the truck start to move above the set locking speed..

If I get out of the truck and hit the lock button, the front doors lock and the lights blink to indicate the alarm is armed but I can open the rear doors and the alarm doesn't go off. I have to manually lock each rear door every time I get out.

Can anyone help me solve this?

Thanks, DEWFPO

[cobrajet84]

check fuses first or maybe the relays, my father in laws truck had bad relays and his locks wouldnt work, worked fine after the relays.

[dewfpo]

Thanks CobraJet84,

 

I'll check them out after I locate them.

 

DEWFPO

[dewfpo]

I replaced the relay but no joy. It's a shame it wasn't this easy.

Any other thoughts?

Thanks, DEWFPO

[cobrajet84]

bummer! unfortunately thats the only idea i have, electrical is definitely my weak point when it comes to diy on my truck.

[Duelin]

Have you tried to reprogram them?

[dewfpo]

Well, I swapped the Lock & Unlock relays (after replacing the Lock relay yesterday with a brand new one) and then the rear doors would Lock now, but not Unlock….. weird.

 

So I pulled a couple of fuses that I thought controlled the door locks (a 15A and a 20A). They were both fine but after pulling those 2 fuses and putting them back in, the rear door Lock/Unlock now work fine. I guess pulling the fuse killed the power and reset whatever was wrong. Go figure.

 

Thanks for the help guys.

 

DEWFPO