03 Tahoe door locks--bad ground? Splice pack 203 location

[JMartin515]

Both rear doors and cargo door power locks will no longer go into the lock position, however, they will go to the unlock position just fine.

I suspect the body control module or a bad ground.

Does anyone know where splice pack 203 or ground 203 is located on the 2003 Tahoe? Looking at the wiring diagram in the Chilton book, I suspect is near the in-cabin fuse block located on the left side of the dash.

I have also pulled the connector from the liftgate actuator and probed the wires with a test light with the following results:

Grey Wire: I get positive voltage when "lock" switch is activated.
Grey Wire: I get no voltage when "unlock" switch is activated.

Tan Wire: I get positive voltage when "lock" switch is activated.
Tan Wire: I get positive voltage when "unlock" switch is activated.

Again, all 3 rear doors will go into the "unlock" position just fine; however, all 3 doors will not go into the "lock" position.

It seems to me that the tan wire should not be getting positve current when the "lock" switch is activated. Am I seeing this correctly, or am I missing something? What could be causing this malfunction, a bad ground, or a bad control module?

Thanks,

JM

[Denali]

Hi,
I had the same problem on my Tahoe. After I reviewed the Electrical Diagrams I noticed that there is a difference between 2000 and 2003 Model. The 2003 Model has two relais for the rear doors and the Liftgate. Both Front Doors are being locked/unlocked by BCM. I changed both relais and now the reardoors and Liftgate are operating properly.

[JMartin515]

I finally solved my rear door lock problem.

It was a bad fuse block that is located inside the dash on the driver's side.

I had to replace that fuse block and now all of my door locks (including the rear hatch) work properly.

The bad news is that particular fuse block is a dealer item only, however the $335.00 that I paid for it was worth it.

Apparently, there was a bad contact in the fuse block where one of the door lock relays is located.

I have seen a half dozen posts on other bulletin boards with my similar door lock problem and they all resolved their issue with the fuse block replacement.