No 4hi

[mitten400]

Hi all.

Truck:
1998 1ton with floor shift. Auto transmission.

Problem:
My front diff actuator will not engage when in 4hi.

Verified:
Everything works fine in 4lo and 2hi
T-case engages in 4hi but does not send signal to diff motor. T-case engages in 4hi and turns front driveshaft as designed. The 3 wire t-case switch was melted and unplugged when I got the truck (just bought it). I I stalled a new switch already.

I also pulled the entire harness out of the truck and it’s fine.

I also took the switch back out and held a small screwdriver in the hole and felt it get pushed towards me when I shifted into 4hi so it feels like The t-case is touching the switch.

why am I not getting ground to the front diff motor?

move tried everything I can think of.

 

[RichLo]

New switch or new actuator?

 

[mitten400]

New switch or new actuator?

New t-case switch. Front diff actuator works fine in 4lo. Floor shift t-case so no t-case motor

 

[alpinecrick]

It's been a while since I owned my 91 with manual T-case, but doesn't the shift lever have contacts under the floor console?

 

[mitten400]

It's been a while since I owned my 91 with manual T-case, but doesn't the shift lever have contacts under the floor console?

Sorry I forgot to update with my fix. It was indeed the t-case switch not getting pushed in by the lever inside the t-case. I took the o-ring off, really tightened the threads and now it is making contact in 4hi. I’m assuming the mechanism inside the t-case is worn out and sloppy

 

[alpinecrick]

Sorry I forgot to update with my fix. It was indeed the t-case switch not getting pushed in by the lever inside the t-case. I took the o-ring off, really tightened the threads and now it is making contact in 4hi. I’m assuming the mechanism inside the t-case is worn out and sloppy

Ok, then I was wrong, the switch is indeed inside the t-case. Glad you successfully deciphered it.