Power door locks only lock intermittently

We need to test the voltage out put from the switch when you have it not working. I suspect the switch is loosing connection when it stops working.

However, to clarify this do all the locks on all the doors stop working? If so, none of the switches work? If none of them work it is not the switch.

If it is all of them not working then I suspect the body ECU is the issue. The way to confirm this is to check power coming in and out of the ECU. So we need to monitor the voltage at number 1 on the diagram and then press the unlock button. Then monitor number 2 and press the unlock button. I suspect you will have voltage at number 1 and not at number 2. If that is the case then the ECU is the issue.

Here are some guides that will help with this type of testing:

https://www.2carpros.com/articles/how-to-check-wiring

https://www.2carpros.com/articles/how-to-use-a-test-light-circuit-tester

Let us know what you find or what questions you have. Thanks