4WD Problem

[Z28kid]

All the lights are lit up on the 4wd switch.

2hi
auto4wd
4hi
4lo.

What does this mean?

If i press one it can see it blink but the light stays lit..

I already replaced the switch.

any ideas?

[Z28kid]

sorry 1999 Blazer

[ricksza]

First, codes in the Transfer case control module can be read with a scanner. That would be the best place to start.

This problem can be caused by a bad selector switch, transfer case control module, or a shorted to ground wiring harness.

[Z28kid]

I also meant to say that the 4wd does work.

Also I can hear the clicking behind the dash.

I can hear sounds from under the car to.

If the transfer case has codes would it set off the Service engine light or Service 4wd light?

I already replaced the switch.

any ideas where i might check for the ground wire?

[ricksza]

The clicking in the dash is the transfer case control module. It's in the right front kick panel. The noise under the vehicle is the encoder motor shifting the transfer case.

They provide the ground to the lights in the switch from the module. They would be: purple/black, tan/black, brown, light green/black and pink. It would be unusual for all these wires to be shorted to ground. I would unplug the module and see if the lights go out. If they do, the module is providing the ground.

[Z28kid]

So. If i unplugged the moudule and all the lights go out is that my problem? Then Should i go get a new module. Wouldn't the lights go out anyway if i unplugged that module?

Just to clarify. If it hit 2wd. only that light should come on right? Then if I hit 4hi. Only that light should light up?

[ricksza]

Just to verify, all ranges of the transfer case work?

The wires I told you about, their only function is to turn the lights on. The wires go directly from the switch to the module. After their start up self test, the lights should only be on one at a time to let you know what range it's in. If the lights go out when you unplug the module, then you know that the module is turning on the lights. But I can tell you that I've never had a module do this. There is always a first. Usually a bad module just doesn't shift.

[Z28kid]

Yes the ranges work. But the is all the lights are lit for all ranges. Then if i hit 4hi i can see a blink inside the light. The light will always remain solid but you could see blinking inside it.

Also now it seems like if I hit 4 hi you can see the condition of blinking i explained above it will try and go in auto a4wd. If hit 4lo it tries to go into 2wd.

Thanks for the help. I just wanted to know what i should try next to get this fixed.

[Z28kid]

anyone Please help???