4wd not engaging

1987 FORD RANGER
200,000 MILES • 2.9L • 6 CYL • 4WD • AUTOMATIC
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AVENGERWEEZEL77
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  • 38 POSTS
The overhead unit has no lights on and no sound from the drive train when I press the button. I did check all fuses, and all seemed to be fine. I did pull the module out of the dash compartment to do the test. When I tested it the light blinked 4 times and to my knowledge that means the module is good. How can I bench test the motor on the back of the transfer case? Also, how can I test the overhead unit for the w4d? Just because the lights do not light up the lights may just be blown. Thank you for your time.
Mar 21, 2022 at 3:51 AM
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KASEKENNY
  • ✓Experienced Mechanic
  • 18,907 POSTS
The light flashing is just proving that the module has the ability to flash the light which does prove out this part of the system.

However, we need to find out if the button is sending the voltage to the module to ensure it is operating. So, let's check the white/purple wire to make sure the module is getting power.

https://www.2carpros.com/articles/how-to-check-wiring

Then the next thing is to check the power from the roof console to the module.

Basically, we need to find out if the module is getting power as it should and finally check the output to the shift motor. We are looking for power in but not out of the module in order to determine if it is a module.

Otherwise, it may be a switch issue. Let me know if you have questions about this and we can go from there.

Thanks
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Mar 22, 2022 at 1:04 AM
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AVENGERWEEZEL77
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Hello. sorry, it has been a little while, just had to get other things done. Well, I did everything we discussed and then some. I ended up taking the motor off the transfer case and checking it out. I redid some of the wiring that looked suspicious. I hard wired the motor to a 12-volt source to see if it would turn at all which it did. Cleaned everything up and put the motor back on. Well to my amazement I started the truck and pushed the button, and everything seems to be working just fine now. All I can assume is in everything I had done all at once, whether it be a bad wire, grim, or the motor was just bound up or frozen it all seems to work now. Thanks for all the help once again.
Apr 16, 2022 at 9:02 AM
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KASEKENNY
  • ✓Experienced Mechanic
  • 18,907 POSTS
Yep. I think you nailed it. More than likely you had a connection issue or a wire. Unfortunately, it is hard to know for sure now, but the fact is, this is working, and we appreciate you updating us and letting us know what happened.

This info will surely help others.

Thanks again.
Apr 16, 2022 at 10:02 AM
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