Door lock problems

Tiny
SIXFOOTTEN
  • MEMBER
  • 2003 CHEVROLET SUBURBAN
  • AUTOMATIC
  • 203,300 MILES
I have an SUV that is having unlocking problems with keyless entry. The remote switch unlocks the two front doors but none of the others. We have replaced the fuses in the interior fuse box which only temporarily fixed the problem. We have heard anything from the relays to actuators are bad. I want to make sure before we replace what is not necessary. What can be done to either narrow or pinpoint the problem?
Friday, January 6th, 2017 AT 4:59 PM

4 Replies

Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
It has to be scanned for codes to make sure the module is not the culprit. Only a mechanic can do this.
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Saturday, January 7th, 2017 AT 8:27 AM
Tiny
STEVE W.
  • MECHANIC
  • 15,434 POSTS
Do the locks work okay with the door switches? You say it will not unlock the doors, but it does lock them? If so the probable cause is a bad unlock relay. Swap the relays and see if now the doors unlock but do not lock.
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Saturday, January 7th, 2017 AT 10:20 AM
Tiny
SIXFOOTTEN
  • MEMBER
  • 2 POSTS
HMAC thank you I will check with a mechanic on seeing if there is a code that may help.

Steve W, we already replaced the relay in the fuse box and it did not fix the problem. As for the locks inside it does the same as the remote switch where it locks all doors, but only unlocks the front two. It has been told to us that there are relays in each door to check as well. I have not had time as of yet to see if that is the case.
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Saturday, January 7th, 2017 AT 12:27 PM
Tiny
STEVE W.
  • MECHANIC
  • 15,434 POSTS
OK if the switches do the same the trouble is in the wiring that is around those relays. You swapped one relay correct? Swap the other one as well. They work as a team. When you trigger lock/unlock. One relay acts as a ground path while the other relay provides power.
If the ground path in the "unlock" relay is bad the door locks won't lock. If the relay swap doesn't work there are easy tests to find the problem.

To test the system you will need two tools, a test light and a short jumper wire. The tests can be done right at those relays. Should take about 20 minutes to do.
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Saturday, January 7th, 2017 AT 3:37 PM

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