4wd light stuck on

i'm stumped on this. i put in a new front diff for a regear a few months ago. it was good and working before it was put into my truck so i know nothing is broke. but now my 4wd light is always on even though it still works as normal - 2wd and 4wd hi and low

i was just ignoring it for the last few months but i forgot about it being on 2 mornings in a row this week and decided it may be time to fix it.

 

ADD or man hub

 

ADD

 

With ADD this is the sequence of events when 4wd is engaged.

The transfer case is shifted into 4wd with a manual stick or an electric motor and a 4wd switch on the case is activated. At this point the front drive shaft and the ring/pinion is spinning at the appropriate speed to allow the ADD actuator on the diff to "connect" with out much complaining. The 4wd dash indicator is controlled by a switch in/on the ADD actuator with both the electric and the vacuum versions.
I would start by looking at that switch operation relative to the position of the ADD shift fork.

AS Toyota likes to say, "HINT" Keep in mind that you can shift the transfer out of 4wd but the 4wd light will not go out until the ADD has finished it's job.

 

the ADD fork, are you speaking of the 4wd shifter? if not where is that at?

 

The ADD fork is in the ADD actuator. It slides a splined sleeve between "intermediate shaft 1 and 2" on the pass side of the diff, connecting them together (4wd) or disconnecting them (2wd).

 

One more thing, because your transfer can be in 2wd and the ADD system in the 4wd position (malfunction), a quick check of this condition would be to jack up 1 front wheel and spin it (transfer in 2wd). If the front drive shaft spins, the ADD actuator is in the 4wd position, keeping the dash light on.

 

gotcha. i'll look more into it this weekend. i may be posting with more questions, thanks

 

We posted at the same time, don't miss post #7 for a quick check.