4WD light is wrong!

[jarod]

Hello. This is my first post, but have read most of them. This site has helped me with a few problems since i got my truck, but this one i have not found the answer to.

2001 1500 4x4 5.2L

The 4wd light comes on only when I am in 2H. N, 4L, and 4H the light stays off.
The 4wd and 2wd work fine, i tested with a little gravel pit fun.

I have had the truck for a little over 2 weeks now and just noticed today because it was the first time i thought i might need 4wd. So in the last 2 weeks i have put about 1000 miles on 4H. Might explain the 13mpg.

I have looked in the service manual that a got from a link somewhere on the forum. It basically says (if i understand correctly) that when the front axle vacuum pump engages the axle it hits a switch to ground the light on the dash.

Soo if there was a short to ground in the wire, the light would stay on constantly. If there was a bad ground or a break in the wire, the light would never come on. And if it were possible to plug a connector to the switch in backwards the light would still operate normally.

So what could cause the light to be completely opposite? Any Ideas

 

[iSlacker816]

Cheap fix there is a vacuum switch on top of your transfer case. 4 vacuum lines plug into it. Sounds like it may be sticking and it's really cheap. Less than 20 bucks from parts store I believe, don't quote me it's been a while since I replaced mine. I'd start there man, hope it works out for ya. Oh and if you've been driving around in 4H, you might want to start looking for a transfer case, thats terrible on it on dry pavement....

 

[ohio mossy oak]

I had similar issue.Did plugs,wires,cap an rotor button(buddy helped)..And he cracked a vacuum line right behind the distributor Maybe it run to the TCase.I cant say for sure..My 4wd light was being wacky..I took it for a drive an came back an told him.."you broke it you fix it".."Im getting a beer....Patched it up an have been good to go since

 

[jarod]

Solved

Hours of google research finally led me to the answer.

There is a vacuum/switch on the top of the transfer case. has 4 vacuum lines on it arranged in a square. It will go on four different ways. 2 of them will give you a correctly working 4wd with light. and the other 2 seem to give you a correctly working 4wd with an opposite light.

Thanks for your suggestions