I'm hoping someone can help me with on how to check the wires for the Selector switch for switch 4WD mode.

I have a 2000 Jimmy with the 4 buttons so the NP8. I am pretty sure there is a problem with the wiring but not sure how to test. I get code B2725 but I have tested the buttons themselves as well I tried 3 different sets of new buttons with the same result. When I press the button for say 4hi it will light and switch to 4hi but not always sometime the 4i light will not come on and I stay in 4hi as if I never pressed the button the same for any. So lets say I do switch to 4hi and then decide to switch back to 2hi, if I press the button it might not light up so nothing happens and other times it will and easily switch the same is for AWD and 4 LO.

How can I test that the correct voltage or signal is even being sent to the TCCM?

Thanks for any help you can give

 

The way it works is an 8V reference signal is sent from the TCCM to the switch. Depending on which button you press (or don't press) this voltage goes through different resistors and the resulting voltage is sent beck to the TCCM to tell it what button (if any) is being pressed at the switch. Lights in the switch buttons are directly controlled by the TCCM - so the status lights are really independent of what you are pressing and only reflects what the TCCM is doing or thinks it is doing.

A code B2725 indicates that the TCCM is not getting the correct voltage range back that is constant when no buttons are pressed on the switch. So check for 8V at the appropriate terminal on the switch. If you have the 8V, then check the switch output back to the TCCM. It's either going to be a TCCM, a switch, or a wire - and you say that you have already replaced the switch several times. This one is EASY!! All you need to know is in these links below, including resistance data for the switch when different buttons are pressed, and complete wiring schematics for the NP8.

Good luck and best wishes for a successful repair.

https://blazerforum.com/forum/diagno...plained-35165/

https://blazerforum.com/forum/tech-a...rmation-41198/

https://blazerforum.com/forum/2nd-ge...-blazer-89044/