Diff Lock Light comes on faintly while driving, please help SEARCHED (1 Viewer)

[95ToyCruiser]

Yesterday I noticed my rear diff lock light was on very faintly, enough to only notice when dark out. It is still on, the locker still engauges as it should. I checked/cleaned the plugs at the acctuator.

Has anyone ever experienced this?

Thank you in advance, Shane

 

[95ToyCruiser]

Oh and as you can see from my sig line it's a 95 FZJ80 with factory locking diffs, no work has been done in the area lately, haven't even been out on the trail, hell hasn't even seen rain/water for a week prior to this happening. Has anyone had trouble with the locker ECU in the past?

 

[IdahoDoug]

IIRC, it's illuminated solid by a ball/position switch in the diff. Could you have a metal slurry in the diff oil enough to make a faint ground? If you have an FSM you might take a glance at the wiring diagram.

DougM

 

[Mark W]

I have this problem om a '93 that also has a slew of electronic related problems with the CDL and the ABS. The rig sat submerged for a few hours earlier in it's life. Everything else came through okay but these two systems were never right afterward. In this case I am assuming it is a flaw in the ECU for one or the other of these two interconnected systems causing the faint illumination effect. Wen I get around to rebuilding it all I will post up what it was... but that is all I can offer for this discussion, this job is pretty far down on my priority list.


Mark...

 

[95ToyCruiser]

I shouldn't be worried about the fact that it is constantly on? It won't burn anything up? Also it doesn't do it all the time, I got in it this morning and it wasn't. Hard to tell if it was too faint to see in the daylight though.

Thank you for the help.

 

[TrickyT]

The dashboard locker lights are controlled by two things, position switches in the lockers and the locker control 'computer.' The diff lock ECU is located inside the passenger-side kick panel. You can isolate which is causing the light to come on faintly by temporarily unplugging the ECU. If the light is still on, then unplug the rear actuator. If it's still on with both unplugged then it's a partial short to ground somewhere in the wiring. The EWD does not give details about the circuitry inside the ECU, so if the ECU is at fault then the only option is to replace it or just live with the problem.

 

[95ToyCruiser]

Thank you very much for the advice, I think I will order a CDL switch and do the 7 pin mod while I'm in there, it's a good excuse to do it anyway. Thank you very much.

 

[TrickyT]

Thank you very much for the advice, I think I will order a CDL switch and do the 7 pin mod while I'm in there, it's a good excuse to do it anyway. Thank you very much.

The 7-pin mod involves changing a wire on the ABS ECU, which is in driver's side kick panel. The front/rear locker control ECU is in the passenger kick panel. Two completely different control units.

 

[Pin_Head]

Generally when a light comes inappropriately and dimly, there is a "floating ground" somewhere that is connected to the lit circuit through the same ground plane that is that has a bad ground connection. The current that would otherwise be returned to ground is flowing through the bulb until it finds a good ground and this current is dimly lighting the bulb. In short, clean the grounds in the panel and the diff lock circuits and see if it goes away.

 

[95ToyCruiser]

Thank you, I will try that, and good thing you said something about the diff lock ECU being under the pass side kick pannel, cause I would have been unplugging the ABS ECU.

 

[Tools R Us]

This is what happened, causing my center diff light to stay on.

https://forum.ih8mud.com/80-series-tech/59333-little-cdl-issue.html

 

[bvissers]

In most likely hood it is the ball switch at the diff as it is the most " exposed " device, to see if it is the problem simply disconect the the switch at the diff ( 2 Pin conector ) if the light goes out you know this is the problem, you can also measure the swicch, it should be almost infinite with diff unlocked, and almost zero locked. I my case it would vary to a few hundred ohms and cause my diff lock light to come on faintly. This is also the easies thing to check before checking ECU's etc.