no 4wd

[dcil]

I've got a 99 Tahoe that I bought from a moron. He yanked the dash out and barely had it back in. He is also one of those people who wouldn't give you a straight answer if his life depended on it, but for what I got it for I can't complain.

That's the back story.

Here's the problem. The switches won't light up, no 4wd whatsoever. Everything is connected (so far), no blown or missing fuses.

I've searched here, searched google, and cant find a good start on testing other than the diagnostic check. Anybody have a pinout/voltage chart for the components and maybe a good starting point?

 

[BlackBearYukon]

The switch itself may be bad. My HVAC control unit did that. Once I replaced the control unit everything worked just fine.

 

[dcil]

Oddly enough my hvac control is trashed too. Will try a switch first

 

[clownracer]

es.

I've searched here, searched google, and cant find a good start on testing other than the diagnostic check. Anybody have a pinout/voltage chart for the components and maybe a good starting point?

i have been looking for a flow chart to diagnose my 4wd for almost a month now

 

[dcil]

I've found several things, nothing really useful at this point. Can't even do diagnostic check. It won't light up.

 

[SunlitComet]

you have to get a scanner to diagnose the electronic shifter units in the 1998-99 units. and what does not light up? push button panel, 4wd service light on cluster? I want names!

 

[dcil]

you have to get a scanner to diagnose the electronic shifter units in the 1998-99 units. and what does not light up? push button panel, 4wd service light on cluster? I want names!

I've scanned it with a cheapo scanner, didn't show any 4wd codes. Gonna take it to my brothers shop and use his real scanner on it. The service 4wd light stays on constantly. The switch panel doesn't light up. Press any button you want, doesn't do anything. I did get a light once. I turned the ignition on after removing and re0installing the switch. All the lights came on for half a second and never did it again.

 

[SunlitComet]

yeah the tcase codes are not based on sae standards so to speak. they are specifically gm's standards.

 

[retorq]

Maybe you have a 2wd truck??

 

[SunlitComet]

Maybe you have a 2wd truck??

with a 4wd service light on.