99 suburban door locks inop when hot

Hey all. So i have a 99 burb obs and the door locks will randomly not work when its hot. Doesn't matter if i use the fob or the switch on the door. I tested all the switches and made sure they had power and were responding voltage wise( my stereo guy did this for me) thinking i needed to have an aftermarket keyless entry installed. The switches work fine and i even swapped my extra ones just to be sure. I used a spray lubricant on all the rods and moving parts in the doors to make sure it was working correctly and put electrical grease on the plugs and he used some little tool to clean the plugs as well. This afternoon they worked fine and it was about 98 outside. In the mornings when its cool they work. When i left work about 30 min ago they wouldn't work and i had to use the key. You could hear the clicking in the door but nothing happens. Kinda stumped here since all the stuff that would be suspect doesn't have the normal issues.


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If you repeatedly hit the unlock button, do they slowly unlock? If so, that's usually a weak lock actuator. Unless this is happening simultaneously on all four doors?




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east302 said:

If you repeatedly hit the unlock button, do they slowly unlock? If so, that's usually a weak lock actuator. Unless this is happening simultaneously on all four doors?




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No they don't. I would have welcomed that fix lol. And it does happen to all 4 doors and the the rear barn doors at the same time.


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Here are the diagnostics for a 98 Tahoe, it should be the same as your 99. It is basically using the keyless entry to test the door lock relay as this is what grounds out the door lock actuators when the lock/unlock is pushed. If it isn't switching over, nothing is going to work.













Door lock relay connector...




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east302 said:

Here are the diagnostics for a 98 Tahoe, it should be the same as your 99. It is basically using the keyless entry to test the door lock relay as this is what grounds out the door lock actuators when the lock/unlock is pushed. If it isn't switching over, nothing is going to work.













Door lock relay connector...




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Thank you for that tech sheet!!! Ill be tearing in to this this weekend!!


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