'91 4x4 module test?

[mpierich]

Hello,

OK, I figured out how to search the site - sorry. I still have a question: Can anyone verify that the test on the module works? My understanding is that you disconnect the connectors, then push the test button. If it blinks, the problem is the shift motor, if it stays lit the problem is the module itself. That inplies that if it doesn't light at all, there's no problem. Anybody ever actually do this?

thanks.

 

[mrboyle]

From my experience the "module test" works 0% of the time. If you are having trouble getting the 4wd to work you need to start by removing the shift motor and use direct 12 volts to shift the motor into low range. Then using an adjustible wrench put the t-case into low. Reinstall the shift motor, put an indexing mark on the contact cover, then remove it, clean the contacts and reinstall the cover (lining up the index mark).
This will reset the 4wd module and if everythig is still in working order you 4wd should be fixed. If it still doesn't work the shift motor is most likely the cause of the problem. I have never seen a module or control button fail.

 

[agzaretzka]

If it blinks, the module passed its self-test; steady lit or not is a failure. It does not test any other compenents of the 4x4 system. People like to say that if it passes then " the problem is the shift motor" simply because it is the most common point of failure if the electronics are working, but that is not necessarily so.

 

[Tedman]

what ever you do, do NOT!....

What ever you do do NOT TAP the shift motor.
I did that and smashed the magnets inside of it and have to replace the whole shift motor.

There is a thread here in this forum that shows you how to rebuild the shift motor.
read it and do it. its simple i should have read it before i started to hammer it.

 

[mpierich]

From my experience the "module test" works 0% of the time. If you are having trouble getting the 4wd to work you need to start by removing the shift motor and use direct 12 volts to shift the motor into low range. Then using an adjustible wrench put the t-case into low. Reinstall the shift motor, put an indexing mark on the contact cover, then remove it, clean the contacts and reinstall the cover (lining up the index mark).
This will reset the 4wd module and if everythig is still in working order you 4wd should be fixed. If it still doesn't work the shift motor is most likely the cause of the problem. I have never seen a module or control button fail.

Thanks, we still have warm weather here so I'll try it this week.

 

[mpierich]

If it blinks, the module passed its self-test; steady lit or not is a failure. It does not test any other compenents of the 4x4 system. People like to say that if it passes then " the problem is the shift motor" simply because it is the most common point of failure if the electronics are working, but that is not necessarily so.

Mine stays lit but I will take off the motor and check it - maybe it has fooled the module somehow. Thanks.

 

[mpierich]

What ever you do do NOT TAP the shift motor.
I did that and smashed the magnets inside of it and have to replace the whole shift motor.

There is a thread here in this forum that shows you how to rebuild the shift motor.
read it and do it. its simple i should have read it before i started to hammer it.

Well, I may still try tapping it but not hard enough to damage it...in these caes setting up a vibration in the case is usually the goal so a lot of small taps is usually better than a few large whacks.

I did find the motor rebuild thread, it's great.

Thanks a lot.

 

[Dopler174]

:thumbdwn: I hate push button four wheel drive. I like the old days when you just pulled a lever. Kinda like big blocks...don't know what you got till it's gone. I think I'm gonna throw my shift motor off a cliff.