4WD not working does not appear to be in 4WD

Tiny
JAECHOLSJR
  • MEMBER
  • 1990 CHEVROLET 1500
  • 4.3L
  • 6 CYL
  • 4WD
  • MANUAL
  • 150,000 MILES
Truck listed above is a K1500 WT with 4WD and floor shifter. Will go into 4 lo and work properly but light on 4 WD indicator goes out when moved to 4 hi. Does not appear to be in 4WD at this point. Will not light up when moved from 2WD to 4WD hi. Where do I need to begin looking to figure out issue?
Sunday, May 2nd, 2021 AT 2:54 PM

1 Reply

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,176 POSTS
Hi,

When you shift to 4wd (hi or low), a signal is sent to the front axle actuator to engage the front wheels. SInce it works in low range, the actuator seems to be working.

Since you are not getting a light when shifting to 4wd hi, I have a feeling there is an issue with the linkage itself. It may simply be out of adjustment.

Let's start by adjusting the shift linkage for the transfer case. If you look at the two pics below, they provide directions for adjustment. Try this and let me know what you find.

Take care,

Joe

See pics below.
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Friday, May 14th, 2021 AT 11:20 AM

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