Flickering 4wd light

[Bwilkins]

Brand new here...just bought an 89 GW...and super excited to get working on it.

One of the things (of many) I've noticed is that the 4wd drive light flickers when I'm in 2wd. It has no problem staying in 4wd when it's selected. 4wd does seem to work, I can get both 4wd hi and lo to engage.

Any suggestions on what might cause this?

Thanks,
B

[Chevelleguy]

Bad switch, maybe. The switch is mounted on the transfer case and is depressed by the mode actuator arm inside the case. It has power to it all the time, so it sounds like it may be grounding internally. If you unplug the wire going to it (orange, IIRC) and the light goes off completely, you know it's the switch. If it still flickers, then you have a short in the wire somewhere that is allowing a path to ground (although not are good one or the light would be on all the time).

[babywag]

'89 the bulb is hot all time, switch is just a ground IIRC.
bad switch or bad wiring would be my guess.
switch is easy to find, do you own a multimeter?

[Bwilkins]

I do...probably more comfortable with a meter than a wrench

I'll check and see if the switch is shorting out, or if the switch itself is bad.

I may be way off...but the switch on the dash, arent there vacuum lines running to/from it? I can hear air when I flip the switch.

[babywag]

Yes it is a vacuum switch under dash.

[joe]

I do...probably more comfortable with a meter than a wrench

I'll check and see if the switch is shorting out, or if the switch itself is bad.

I may be way off...but the switch on the dash, arent there vacuum lines running to/from it? I can hear air when I flip the switch.

Yeah it's a vac switch that controls the shift motor on the case but it has nothing to do with the light operation. A phhht sound is normal when you move the dash lever.

[gpcl16]

I had exactly the same problem with my '88 when I first bought it. Would shift fine in and out of 4wd but light often remained on or flickered in 2wd. I removed and tested the switch and it was working fine. Wiring was also fine. The best I can understand it there is a lever inside the transfer case that physically pushes on the switch when it is either in 4wd or 2wd (can't remember which). Anyways, in my case it turned out the mode lever on the transfer case needed a slight adjustment and it has been working fine ever since.