4X4 electric shift issues?

BRETT4USM

MEMBER
1989 FORD BRONCO
5.0L
V8
4WD
AUTOMATIC
120,000 MILES

I am not getting power to the transfer case to engage my 4WD. I have tested the plug and I am getting 5V +/- on 2 locations. 0 volts in the rest. I have identified the holes at 11 o’clock, 1 o’clock, and the center as ground.

Checked all fuses and the control Module. All are in good working order. I just can’t seem to find where the power originates or how to back track to solve the issue.

4 Replies

KEN L

MASTER CERTIFIED MECHANIC
47,642 POSTS

Here is a guide to help check for power and the transfer case wiring diagrams so you can see how the system works and where to check for power from.

https://www.2carpros.com/articles/how-to-use-a-test-light-circuit-tester

Check out the images (below). Please let us know what happens.

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Saturday, April 22nd, 2023 AT 5:06 PM

BRETT4USM

MEMBER
15 POSTS

I have tried my best to follow the schematics but still getting nowhere. I think that it is the electronic shift control module.
I ran the self-check by unplugging and pressing the white button. It flashed on and
Off for about 15 seconds. Reading another board and they said that means it is functioning properly. I am only getting 5 volts from the white/blue wire coming from module to transfer motor.
Is it possible for it to test properly and still malfunctioning?

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Sunday, April 23rd, 2023 AT 3:30 PM

BRETT4USM

MEMBER
15 POSTS

The dash lights are also showing (parking brake, antilock brake, and engine) lights all on.

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Monday, April 24th, 2023 AT 7:18 AM

KEN L

MASTER CERTIFIED MECHANIC
47,642 POSTS

I would check the power and ground inputs to the shift control module, can you see which ones there are from the wiring diagrams? Ground is pin #6 power is pin #3 and #4. Use the test light guide for the test. Unplug the module first.

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Tuesday, April 25th, 2023 AT 8:20 AM