Worst damn electrical system ever.

[Vanquish502]

Problem: Low Range no engaging.

First off the truck is a 92 XLT. With the first 4x4 computer, pressing the low range button did nothing. 4HI worked, but 4LO did nothing. I took the computer out of my truck, which is a 91. Put it into the 92.

Now, the low range light flashes, and does nothing else. I'll put it in neutral, not moving while holding the brakes, and still nothing. Just flashing...

When you press the button you can here the transfer case 'ting', but the light flashes, and the trucks still in 4HI when you move it.

When I had the computer in my truck, low range worked perfect. Is this computer not compatible with a 92 or something?

 

[410Fortune]

tHE TRUCKS COMPUTER HAS ABSOLUTELY NOTHING TO DO with the electric shift 4x4 system.

Why did you swap computers? And no not all 91-92 computers are the same.

First off I want to make sure you know the proceedure for switching the T case into low range. it must be stopped and in N or P (5 speed, clutch pushed in)

It is very common for the transfer case shift motor to quit working properly. You should try a search for this, it can be "rebuilt" quite easily and work like new again .

I would guess this is your problem, not the trucks computer

 

[EMG7895]

Obviously you do not know Lucas electronics, get yourself an old Jaguar then you can complain about electronics. You probably have a problem with the bushing or contacts in the shift motor.

 

[410Fortune]

also didnt said electrical system just last you 13 years or so?
Mine has 280K miles on it, one rebuilt shift motor and works flawless I say thats pretty damn GOOD

 

[MalcolmV8]

First off I want to make sure you know the proceedure for switching the T case into low range. it must be stopped and in N or P (5 speed, clutch pushed in)

In addition to what 410Fortune said my stock 94 Ranger also required I be pressing on the brake. Just been stopped alone was not enough. I had to actually be pressing on the brake pedal and clutch.

 

[Vanquish502]

I didn't switch ECUs...I switched the 4x4 computer. The one that was in the truck didn't let 4LO do anything, light didnt flash, no 'ting', no anything. Now atleast the light flashes.

Yes I am stopped and neutral, and brakes and everything, just doesnt go in...

 

[410Fortune]

put the old 4x4 shift computer back in, rebuild the shift motor, or at least check its motion at the t case.

Did you do a self diagnosis of the 91's computer?
I have heard the 4x4 shift computer (aka Gem module, however not like the new trucksm where one GEM module does a ton of crap, this sucker only does the 4x4 shift system) going out, but have never seen one be the cause of T case shifting issues myself.
Wiring or shift motor, yes.

 

[DeRocha]

As Fortune alread stated the shift motor is the problem 90%+ of the time. Under the geared selector cover is a plastic stop which deteriorates over time. This can cause the selector to move slightly beyond its range when being powered by the 4x4 computer at which point it will stop moving. After cleaning my shift motor I had to fine tune the cover position so that the appropirate electrical continuity was obtained (see info in maint link below).

 

[410Fortune]

OH yeah and a nice piece of plastic hose makes a great new stopper.