97 yukon 4wd actuator upgrade

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Grube

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Well, finally got some time to address my 4wd actuator on front axle. Went ahead and ordered the upgrade kit from old Thermal to newer style. Used Dorman 600-600 harness and Dorman 600-601 actuator.

Removed thermal actuator, cleaned threads, installed new spacer plug. Applied threadseal to new actuator and wind into housing and tightened. Went to plug the "plug and play" harness in, and the 2-pin plug that connected the old actuator was a different style. So I had to cut the plug pigtail off the old actuator, cut the plug end off the new harness, and splice the old pigtail onto the new harness with dual wall heat shrink connectors. After confirming the Blue wire was indeed power, and black was ground. The brown wire they suggest to run to 4-pin plug on top of tcase. Looked like P.I.T.A. to get at, so I ran the brown wire up to engine bay, over to driver side along top of firewall and through firewall under brake booster (hole drilled, rubber grommet installed). Once in cab, had to lengthen wire 10" (used red as I had no brown), and attached to the rightmost pin on the DRK GRN labelled connector under dash. This pin is powered by the 4WD 25amp fuse, and is key-on switched power.

I haven't drive tested the truck yet, as it's still on stands while I fight off an extremely stubborn fuel filter. But I did push the switch while in the air, and could here the actuator engage. So that's good. Although my 4x4 buttons in the dash have started acting up as well as of last week. If you push in on the dashboard underneat the switch, the LED will come on and you can use the switch. As soon as you let go, the lights go out and switch function is gone. If not one thing, it's another right.

Attached pics of old / new actuator, and the location I ran the brown (now red) wire too. Don't mind the compustar auto start hanging down, I'm also trying to figure out why that keeps blowing it's 25Amp fuse if fan is above low setting. Maybe my fan draws too many amps, at least compared to the newer vehicles this brand-new compustar is likely meant for. Not quite sure how I'm gonna address that yet. Maybe put a 30amp in lol.
 

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HotWheelsBurban

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Well, finally got some time to address my 4wd actuator on front axle. Went ahead and ordered the upgrade kit from old Thermal to newer style. Used Dorman 600-600 harness and Dorman 600-601 actuator.

Removed thermal actuator, cleaned threads, installed new spacer plug. Applied threadseal to new actuator and wind into housing and tightened. Went to plug the "plug and play" harness in, and the 2-pin plug that connected the old actuator was a different style. So I had to cut the plug pigtail off the old actuator, cut the plug end off the new harness, and splice the old pigtail onto the new harness with dual wall heat shrink connectors. After confirming the Blue wire was indeed power, and black was ground. The brown wire they suggest to run to 4-pin plug on top of tcase. Looked like P.I.T.A. to get at, so I ran the brown wire up to engine bay, over to driver side along top of firewall and through firewall under brake booster (hole drilled, rubber grommet installed). Once in cab, had to lengthen wire 10" (used red as I had no brown), and attached to the rightmost pin on the DRK GRN labelled connector under dash. This pin is powered by the 4WD 25amp fuse, and is key-on switched power.

I haven't drive tested the truck yet, as it's still on stands while I fight off an extremely stubborn fuel filter. But I did push the switch while in the air, and could here the actuator engage. So that's good. Although my 4x4 buttons in the dash have started acting up as well as of last week. If you push in on the dashboard underneat the switch, the LED will come on and you can use the switch. As soon as you let go, the lights go out and switch function is gone. If not one thing, it's another right.

Attached pics of old / new actuator, and the location I ran the brown (now red) wire too. Don't mind the compustar auto start hanging down, I'm also trying to figure out why that keeps blowing it's 25Amp fuse if fan is above low setting. Maybe my fan draws too many amps, at least compared to the newer vehicles this brand-new compustar is likely meant for. Not quite sure how I'm gonna address that yet. Maybe put a 30amp in lol.
Post a picture of the dash switches for the 4wd, I may have a pair if I think they're like the ones I have.
 

Grube

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Post a picture of the dash switches for the 4wd, I may have a pair if I think they're like the ones I have.

It is just like this one.

I just some success just smacking the dash until the lights stayed lit up. So far so good, until the next speed bump anyway lmao
 

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AuroraGirl

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Drivetrain - Slow Or No Engagement of Front Axle

File In Section: 4 Drive Axle

Bulletin No.: 76-43-01A

Date: September, 1998

Subject:
Slow or no Engagement of Front Axle when 4WD is selected (Replace Front Axle Actuator)

Models:
1988-97 Chevrolet and GMC K Models
excluding 1988-93 Models over 8500 # GVW

This bulletin is being revised to add information to the Service Procedure, add a new part number, and include schematics. Please discard Corporate
Bulletin Number 76-43-01 (Section 4 - Drive Axle).

Condition

Some owners may comment that the colder the outside temperature is, the longer it takes for the front axle to engage when 4 wheel drive is selected, or
the front axle does not engage.

Cause

The front axle engagement actuator is a thermally activated component. Because of this characteristic, the time required for the actuator to complete 4
wheel drive engagement is extended as the temperature drops.

Correction

Replace the front axle actuator and include the applicable wiring harness kit. Refer to the Parts Information in order to determine which wiring harness
kit is needed.

1996 model trucks with a build date on or after January 2, 1996 are considered as "961". If the build date of the truck is unknown, verify the 3 character
"axle code" on the front axle label in order to determine which wire harness to order.
You must be registered for see images attach


This new actuator uses a motor to engage the front axle and is not affected by temperature. On 1988-93 models with a GVW rating over 8500$, the new
actuator cannot be installed and the thermal actuator will remain the service part.
 

Grube

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Bulletin No.: 76-43-01A

Date: September, 1998

Subject:
Slow or no Engagement of Front Axle when 4WD is selected (Replace Front Axle Actuator)

Cool to see the bulletin. Thanks for posting that.

As an update to my original post - my 4wd is working nicely after replacing that actuator. My dash switches had a poor connection behind the dash as well.
 
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