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Dave Nova
Dave Nova, Chevrolet Technician
Category: Chevy
Satisfied Customers: 19452
Experience:  ASE Master Certification. GM World Class Certification
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2003 Chevy Suburban: door locks..rear doors..driver seat..key pad

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My 2003 Chevy Suburban door locks for the 2 rear doors and the tail gate door do not work properly. You can't lock them from the from driver seat locking buttom or from the black key pad when you are locking the entire car. When you try to lock the entire car from the outside, only the front two doors lock. The other three do not.
Customer: replied 6 years ago.
Relist: I still need help.

Hello and thank you for using justanswer.

 

Can you lock these doors from the switch, but not unlock them?

Customer: replied 6 years ago.

Dave, The locking problem is with the two rear doors and the rear gate that opens up from the rear bumper. The two front doors lock just fine. Here is what happens. If you try to lock the car from the interior from the drivers controls ( on the door) or by using the black keypad while outside the car, the 2 front doors lock just as they should but the other 3 doors ( rear 2 doors and tail gate) will not lock. They remain unlocked. When you try to open the two rear doors or the tailgate they do open, even though they are suppose to be locked and at the same time the car alarm goes off.

What you can do is lock the 2 rear doors mechanically by using the lock mechanism on each door rear door sepeartely. Then they are locked. The rear tail gate remains unlocked. Next when you use the black handheild keypad to open the car, all 4 lock doors open. Net - net --- the mechanically locks work and they also work via the electronics automaically when you use the key pad to open them. What seems to have happened is that the 2 rear doors and the tailgate seem do no be getting the electronic message to lock when you hit the black keypad nor will they lock when you try to do it from the drivers seat controls

Okay, your problem is a failed lock relay. This is a common problem. The lock relay operates the 3 rear doors. This relay is located in the fuse panel on the end of the drivers side dash. See picture below.

 

graphic

Customer: replied 6 years ago.
David, --- OK, thanks. I opened the fuse box in the drivers side area and by using the car manual I found out which is for door locks. In the owners manual in the fuse display they show it on the top right quatrant and it says "Lock" just like your drawing. When you visual look at it it is not a fuss. It is black box shape. On it you see two numbers, one number is XXXXX and the other number is XXXXX This is the same part ( i.e - the same numbers) and the "unlock" module. My question is do I try to pull the black module out? Do i need to get a new module and re-insert it? Does it make sense that both the "lock" and "unlock" have the same part numbers? I tried pulling it out and it does not want to pull out. Do I need to simply try to pull harder.
Customer: replied 6 years ago.
when you get a chance, tell me if i simply pull the module out. i have tried unsuccessfully
The relay just pulls straight out of the panel. Just grasp it and pull. Use pliers if you need to, you will be replacing the relay anyways, so it will not hurt if you crack the cover.
Customer: replied 6 years ago.
changing the module did not work. i spent $17, bought a new module and it did not fix it.
When you press the lock button, does this lock relay click? Place your hand on the relay, you should feel it click when the lock button is pressed.
Customer: replied 6 years ago.
I tried feeling it and as you know there are two modules side by side. I can here them click and when I try to feel which one is clicking, i can't isolate it. net/ net, when you lock and unlock you here a click
Remove the relay and look at the diagram I provided earlier. Using the diagram, identify terminals 87 and 30 in the fuse panel. Take a jumper wire and connect from terminal 87 to terminal 30 in the fuse panel. The rear door locks should lock. Do they?
Customer: replied 6 years ago.
NO, it does not. Interesting thought the pins in the box are just opposite from what your drawing ( which is the same drawing that is in my manual) have. The module has 3 pins on one side and two on the other side and the acutal holes are opossite from the drawing..... but anyway, #87 and #30 are still in the same corners either way. I made contact between 87 and 30 and nothing happening. .................... When the module is in you here the click on both opening and closing. Obvioulsy when I try to lock it without the module, but #87 and #30 being connected ,nothing happens with the rear doors and you don't hear any click................ Is the problem upstream from this in the Surburban's computer?
No, the problem will be in the unlock relay. I know this sounds backwards, but the ground side of the lock circuit feeds through the unlock relay. Place the old lock relay in the place of the unlock relay and the locks should then work.
Once you try this, please let me know if it worked.
Customer: replied 6 years ago.
Dave --- Thank you for sticking with me on this. You were correct. When I nstalled the new module in the other slot, everything works now!!!! I am a satisfied customer! thanks again.
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