Front diff light on while driving. RTH needed

badmuthatrucka · 10-20-09, 08:14 PM

Okay, after running a trail about a month ago, my front diff lock light came on. It stayed on for about a week, then went off again. This past Monday it came on again. Sometimes it comes on after driving for a while, other times it comes on just after start-up. From steering, I can tell the diff lock isn't actually engaged. And when trying to engage it on dirt, the CDL and FDL engage, but not the front.

I have removed and rebuilt the rear diff lock actuator, so I know how to do that.

Where should I start on diagnostics? Test the sensor, the actuator, something I don't know?

Please help!

IdahoDoug · 10-20-09, 08:39 PM

You said "the CDL and FDL engage, but not the front."

What's the FDL if it's not the front one??

DougM

badmuthatrucka · 10-22-09, 05:05 PM

Sorry, the Rear Diff Lock does engage properly, along with the CDL. The Front Diff Lock indicator light is the one I have a problem with.

badmuthatrucka · 10-23-09, 08:38 PM

So does anyone have any ideas on this or what?

landrunner · 10-24-09, 09:19 AM

I would start with a simple test just to be sure the ground is coming from the front diff lock position switch.

With a meter, check the front switch connector (it only has two pins in it) with the positive meter lead when the light is on, or disconnect the connector to see if the light goes out.

If checking with a meter, both contacts will show "ground" if the switch is made. Otherwise one side of the switch will show a voltage.

If the switch seems to be made, then other tests would need to be done to see if the switch is just bad, or the rod that makes the switch is stuck.

If the switch is not the cause of the light being on, then a trace of the wires would have to be made back to the dash to determin where the ground is being picked up.

Good luck.

badmuthatrucka · 11-04-09, 06:59 PM

Thanks for the help, guys! Ran another trail two weeks ago, engaged all of the diff locks just to exercise them. Everything seems to be fine, the FDL indicator light hasn't come on again. Will still test with a meter to make sure that everything actually is okay.

waldrtw · 11-04-09, 07:38 PM

Mine did the same thing about 2 years ago. It happened after I drove the rig from OR to NC. It would lightup and stay on for about a week or so and then go back off. The front was not engaged when it would come on. No the light never comes on but the front will stil engage when the switch is turned on. I ohmed the sensor and it is bad. Just have not felt like paying the cash to have it fixed. I think the light coming on and off is just the start of the sensor going bad

Tim

waldrtw · 11-04-09, 07:46 PM

http://forum.ih8mud.com/80-series-te...ock-light.html