2nd Gen Non-Engine/Transmission '4x4' indicator lamp

[DannyUpstate]

Trying to diagnose a possible 4 wheel drive problem...



When you start the truck, all the indicator lights come on. Does the 4x4 light also turn on at this time and then go out like the rest of the lights?



Currently it never lights? Maybe It's just the lamp? Wouldn't that be nice??

 

[JDKammin]

The 4x4 indicator light should only come on when the truck is in four wheel drive. I think theswitch in the CAD unit on the front axle is what makes the light come on. You can remove the unit from the axle with four 1/4" bolts. Start the truck up and have someone move the transfer case shift lever in and out of 4x4. The shift arm should slide back and forth, when you shift the lever. There are some wear pads at the end of the shift fork that can wear out and break off. What is the problem?

 

[WilsonF]

If you pull the elect. connector off @ the CAD you can put a jumper across the two contacts turn the key to "on" and the light should come on, if not pull the switch out of the CAD and w/a meter check for continuity w/the switch plunger pushed in. This way you can check the elect. system w/o pulling the CAD off the axel and loosing oil.

Floyd

 

[DannyUpstate]

Thanks for the advice guys.



Right now, set the 4WD selector to 4H or 4L and the light does not come on and I believe the truck does not go into 4 wheel drive.



I'll dig deeper tomorrow and report back.

 

[WilsonF]

If its not electrical pull the two vacuum hose off @ the CAD, w/the engine running have someone shift into and out of 4WD you should feel the vacuum switch from one hose to the other. If you have vacuum then its most likely the vacuum motor.

Floyd

 

[DieselDoghouse]

Welcome to the wonderful world of misdesigned CAD's. There are many posts on this but to summarize:

1. No the 4WD light is an outboard function not part of the bulb check system (to demonstrate this hold the odometer button in, then turn the key to on until the odometer says <CHEC> as the test runs and indicators are lit 4WD will NOT).

2. An extinguished light may mean that the CAD is not engaging - the end of the shift fork rod depresses the switch. OR the CAD is beginning to fail; it is engaging for now but is not strong enough to close the switch. They fail because they sit at road level and moisture eventually rots the unit but also:

3. Strictly IMHO, having gone through several CAD motors (~$200. 00) I believe they may rot from the inside—the air vent under suction during shifting is at road level also and may over time waltz moisture into the lines.

4. Because of #3 I would strongly advise relocating the vent line (strapped to the harness of hoses at the transmission) up behind the firewall hood seal, this has worked for me.

 

[RLHannink]

Mine doesn't work, but I know it's because the wires keep ripping off, due to the leveling kit.

 

[Diesel Gopher]

My light has not worked for a year and a half (on the 02), but it definitely drives in both 4 hi and low. I just figured it is the light and I am too lazy to rip the dash apart right now.



Matt

 

[SSolderitch]

There is 2 plugs to check. the first is on the cad switch and the second is on the side frame rail before it goes into the main harness under the radiator.



RLHannink: You can have the wires in that jumper extended a few inches.



I had found a break in the wire in the main harness. The frame plug was also bad, maybe because I have a leveling kit also.







I believe the switch throws on the ground side. If that is true then 1 wire is grounded - check that. The second wire supplied ground to the led bulb in the dash. So to check that, ground each wire in the plug and one should light the bulb. If no light then a broken wire or bad bulb.



I jumper at the plug and light "on" will point to a bad switch or cad.



Some actually had to replace the led bulb. If you have a manual you can use the o/d bulb. A soldering iron and watch for polarity (don't turn the bulb around) indicated by a flat edge.

 

[RLHannink]

RLHannink: You can have the wires in that jumper extended a few inches.

Yeah, I know. The wires also get ripped off by deep mud, snow, and sagebrush. The light gets annoying at night when I'm running long miles with the cable-lock engaged (ready for slick spots, etc), so now I don't have to worry about that. I guess I should remove them so they don't short something out on down the road.



As long as I know the CAD is engaged, I don't worry about the light not working.