4WD Indicator Light

[techrat]

In an effort to troubleshoot some transfer case problems I am having, I have noticed that the 4WD Indicator Light may be burned out on my 91. I don't have an owners manual but I assume that the 4WD light is in the instrument cluster. When I shift into 4WD, High or Low, I get no indicator light. So I decided to check to see if the light turns on with the engine off and ignition on (Bulb test for all of the other indicators) I continue to get no light for the 4WD indicator.

Can anyone confirm that the 4WD indicator actually does light up with the ignition on but the engine not running.

Thanks in advance!

 

[Ulfr]

In an effort to troubleshoot some transfer case problems I am having, I have noticed that the 4WD Indicator Light may be burned out on my 91. I don't have an owners manual but I assume that the 4WD light is in the instrument cluster. When I shift into 4WD, High or Low, I get no indicator light. So I decided to check to see if the light turns on with the engine off and ignition on (Bulb test for all of the other indicators) I continue to get no light for the 4WD indicator.

Can anyone confirm that the 4WD indicator actually does light up with the ignition on but the engine not running.

Thanks in advance!

What generation is this? There is a sensor on the transfer case that lights the indicator, but that's not all. If you have ADD then there are 2 wires that go to the ADD vacuum stuff on the axle IIRC, that also needs to be connected, tellin' the truck that it's in the hubs as well.

If the ADD system has been removed, it's good to connect these two wires together, either inside or the easier way, just outside the firewall.
It's on the left side, beside the wire loom that comes out of the firewall on the driver's side.
IIRC the wires are "standalone" i.e. they are not inside the huge wire loom. Pretty easy once you spot 'em.

These wires could also be torn apart on the vacuum thingy on the axle (I think it's on the axle at least) or just the plug that's c.a. 30-50cm from the firewall.

It could also be that switch on the transfer case. It's on the right side (passenger side) of the tranny and is the sensor second from the tail of the tranny. The first is the speedometer, electronic or mechanical...

Hope this helps any.

 

[fourwd1]

Looking at the wiring diagram, the 4WD indicator would not light up during the "bulb test".

You could disconnect the 4WD indicator switch at the t-case (top front, pass side) and short the 2 contacts in the harness together as a bulb test, or just pull the cluster out and look at the bulb.

 

[n8buddy]

The first thing you should do it take the gauge cluster out and check the bulb. The 4wd indicator only lights up when in 4wd, not at bulb test. If the truck is in 4wd and the key is in the on position but the engine is not running, the indicator should still light.

If the bulb is fine, check to see if the 4wd is working. easiest way to do this is to put it in 4wd, disconnect the A.D.D. indicator switch and test continuity across the 2 terminals (of the switch, not the wire).

Is your truck manual or auto?

 

[techrat]

Is your truck manual or auto ?

It is an Auto. Thanks for the advice. With the recent 10" + of snow that we have had in the last few days, I am sure that the truck is going into 4wd.

I can live without the light but was in the process of trying to trouble shoot a transfer case problem and wanted to cover all of the bases.

I will check the bulb when I have a chance.

Thanks to all for the advice!