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JOHN aka Eauto
JOHN aka Eauto, The Car Guy
Category: Chevy
Satisfied Customers: 15075
Experience:  ase tech
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My name is ***** *****. I have a 91 Chevy 4x4. The 4wd is

Customer Question

Customer: My name is ***** *****. I have a 91 Chevy 4x4. The 4wd is not working. it worked spastically last year My mechanic looked at it yesterday ad there is no Juice to the wires to the acuator
JA: Thanks. Can you give me any more details about your issue?
Customer: see above i saw a post where a person said that they had a similar problem and it was in the wiring near the 4wd shifter
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Customer: yes
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Submitted: 11 months ago.
Category: Chevy
Expert:  JOHN aka Eauto replied 11 months ago.

have you checked the fuse?

Customer: replied 11 months ago.
There is juice at the fuse box and fuse is ok. I also changed it just I n case. The 4 WD did work sparatically last winter which would not happen if the fuse was blown.
Expert:  JOHN aka Eauto replied 11 months ago.

did you update the harness to the actuator?

Customer: replied 11 months ago.
Does update mean replace I am assuming?
Customer: replied 11 months ago.
Where does that harness start?
Customer: replied 11 months ago.
Is that a dealer item?
Expert:  JOHN aka Eauto replied 11 months ago.

P/N 15313272. CKT 1695 (BLK/WHT) fits into cavity A of the fast actuator. The circuit includes the cable seal and the terminal pin. This circuit plugs into the 5-pin axle actuator connector.................

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 # *****

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*****Axle).

Condition

Some owners may comment that the colder the outside temperature is, the longer it takes for the front axle to engage when*****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*****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.

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.

Customer: replied 11 months ago.
I just called the part store to see if the wiring harness is available. he said to first check that there is juice to the relay switch on top of the transfer case. isn't that the next logical step? He said he worked for a Chevy dealership for 17 years and never had to replace a harness!
Expert:  JOHN aka Eauto replied 11 months ago.

there is a service bulletin on this ..Its a known issue ..I even supplied you with the technical service bulletin and the wire diagram so a little trouble shooting would not hurt. Gm had so many issues with this design that the posted a tech bulletin