4WD indicator flashing in 2 wheel drive
 

2001 dodge ram 3500 auto trans 5.9L cummins - My 4WD indicator is flashing intermittently in 2 wheel drive.

I have tried multiple times shifting to 4WD high and/or low and back to 2WD. In either 4WD high or low the 4WD light comes on and stays on. When I shift back to 2WD the light flashes randomly or sometimes stays full on for a few minutes, then back to random flashing.

I suspect the 4WD switch is intermittent ON, but could be intermittent short to ground somewhere in the wiring between instrument cluster and the switch.

WHERE is the 4WD switch located? My manuals don't tell me. Is it on the transfer case? Is the switch easily replaceable? Or is it inside the transfer case?

Other ideas??

Thanks,
Jack

Check the wires on the front axle, mid-right hand side. The sensor/actuator for the axle is in there.

Thanks RA - Interesting! I can't look right now.

I would have expected that the 4WD switch would be actuated by the transfer shift lever itself, after all, isn't it just to give the driver a visual indication that 4WD is on? Thus, if the vehicle isn't moving (nor the front axle) how would the 4WD lamp stay on?

I'm obviously a bit confused. Can you enlighten me more?

Thanks for the help.
Jack

The T-Case is controlled by the lever, but other components, like the one in the axle, is vacuum controlled. Once the vacuum pulls the collar in, locking the axle in place, it pushes on a sensor to activates the light on the dash. My guess is the wires for the sensor are damaged, sending a false signal to the dash.

Hey RA - Thanks for the great explanation. Now it's perfectly clear.

Now all I need it to find the time to go check that out. At 11 years old, my truck may well have worn thru the sensor wire insulation and have an intermittent short to the chassis. Hope that's what the problem is.

Happy 4th of July!
Jack