no 4WD

[matuva]

Hello,

does any of you have the wiring diagram of 4WD actuation on a 1997 K1500 ?

I'm trying to solve a no 4WD actuation on such a truck.

symptoms when trying to engage are :
- nothing happens, except a click inside the dash, under instrument panel. The clicks come from what I would call a relay-BCM, where wires from switches connect, and from which the harness to actuators is connected
- lights in 4WD switch (Hi and Lo positions) just blink a very few when trying to actuate then go off, lights in 2WD switch always stays on
- while actuating switches, no power (2 volts only) at the actuators, the one on the T-case, and the one in the front end;
- swap the switches with new ones, no change,
- swap this kind of relay-bcm (#1) under the dash with a known good (#2), no change. Note the relay-bcm#1 doesn't work on the truck #2, relay #2 works fine on truck #2, but not on #1 either
- new actuator in the front end, no change
- all fuses OK

I must say I'm a bit lost, so I believe a wiring diagram should help. Any thought BTW ?

 

[great white]

Common failure points are the switch and the rotary encoder (motor on the transfer case).

I'll see if I can scan my 98's wiring diagram later. There's usually a troubleshooting flow chart I'll also see if I can scan...

 

[great white]

Here ya go:

I left them full size so you can blow them up. I wasn't sure what you are looking for, so I just scanned all the selectable 4WD diagrams. There's a separate set for automatic 4wd.

Hope that helps.

Cheers

 

[matuva]

Hey thanks Great White !!!

I hate electrical gremlins, so your schematics will be a greta help to narrow where to focus

 

[diesel65]

The electronic shift system has its own basic diagnostic capability, With the ignition key off for at least five seconds ground pin 13 then turn ignition on and read the flashing code sequence at the shift buttons. There are only codes one thru four.

Pin 13 is on the bottom row and the connector is numbered 9 thru 16 from left to right.

If all the buttons blink one time and stop and does not keep blinking then there are no fault codes in the transfer case control module

Good Luck

 

[great white]

Hey thanks Great White !!!

I hate electrical gremlins, so your schematics will be a greta help to narrow where to focus

You're welcome.

Glad to be of some help.

Those are for my 98, but 97 should be very similar if not the same.