Help..Diagnose a Push Button 4x4 problem!

[Rod Bivens]

All right...I'm desperate now. I have a 94 ranger, and it goes into 4H by pushing the button, but not 4low. I have the tranny in neutral (automatic) with the brake depressed, but just one faine click from the processor and no light or t-case change.

I have been to drbob's web site and performed all the tests and proceedures explained there. I have cleaned the brushes in the motor, made sure the motor was alligned properly, and have been able to check the Motor Position Sensor in 2H and 4Low, and everything checks out OK. Of cource I had to hot wire the motor to get it into 4low.

Does anyone know how I can DIAGNOSE the PUSH BUTTON itself, or the PROCESSOR BOARD? I could really use a wireing diagram, but the repair manual at ford is about $80. I am fairly new to electrical systems, so any basic diagnostics would be helpful. I spent all day yesterday messing with this thing, and I am pretty frustrated.

Thanks in advance,
Rod

 

[Goober]

Not having the switch to look at, can the 4lo switch plug be put on the 4hi switch? If so, you know the wire to the 4hi is ok, you could now test the 4lo switch by putting the 4hi wire on that switch. Did you understand that or am I being confusing?

 

[Rod Bivens]

That's an idea, but I don't know what the switch looks like yet. I will have to take the dash apart to see it. I will definitely try it to check it out.

Has anyone else ever had to replace their push button switch before? Maybe they could shed some light.

 

[Brian1]

This may sound stupid but put the tranny in gear with your foot on the brake. Then see if 4 lo goes in. On my 91 Exp. today, I had to have the clutch in for it to go into 4 and 4lo. I thought it should have gone in when I was in neutral but it didn't. Just a suggestion.

 

[Ray Lobato]

Just pull the switch out and check it with a ohmmeter.

 

[Rod Bivens]

Ok, I have pulled the button, and found that it is an eight pin switch. There was continuity between the White/blue and Dark Blue wires when 4x4 was depressed, and there was continuity between the White/blue and Orange/blue wires when Low Range is depressed. There are no breaks in those lines between the button and the processor board.

I assume that the other five pins turn on the small indicator lights within the switch, but I am not copletely sure.

Does anyone know where I could start to diagnose the processor board. There are three sets of wires going in/out of the processor. One 8pin set, one 5pin set(where the 3 important wires come from the button), and the seven wires that come out of the processor. Where could I begin??

By the way, I have tried to engage low range in any and all gear positions, with no luck.

 

[bgracen]

First thing to do is remove the electric transfer case engaging motor. Place the truck in neutral and with a pair of pliers move the transfer case selector to low range, to make sure the transfer is capable of low range. If it goes into low range, your problem is in the motor, if not it is in the transfer case. I have been working on the ford explorer since they came out if I have never seen a bad switch. I've seen many, many, many bad electric motors, hubs, and a couple of transfercases. I hope this helps.
-Dube

 

[Rod Bivens]

Dube,
I was able to engage 4low by applying 12 volts to the correct pins in the ten pin wiring harness at the motor. Then I was able to check for continuity to make sure that the Motor Position Sensor "knew" it was in 4low. Then I drove it a little, and it was clearly in low range. Pushing the button gets it into 4high and back to 2wheel drive without a problem, and there didn't seem to be any slowness of movement of the motor when engaging low range at all, so I don't think it is the T-case. It also drove without a hitch in Low Range.

As I mentioned earlier, I have taken the motor off, cleaned the brushes and the armature which were fairly black from use, but I wasn't able to clean the Motor Position Sensor contacts because the design has changed and they are not accessible any more.

How would I know if I have a hub problem? I have seen this sugested once before in another post, but would that affect the engagement of low range?



[Edited by Rod Bivens on 09-13-2000 at 10:49 PM]

 

[bgracen]

Rod,
Before I fork over the cash for a new engaging switch, try one from a friends truck, or if not, make sure you can return the one from the dealer should this not be the problem. As for the hubs, its been my experience that the automatic hubs are either good or their bad. When they are bad, they soemtimes pop/clunk when in 2wd/4wd, or when the transfer case is engaged the hubs make no noise at all and you are only in two wheel drive. If it was my machine personally, I would upgrade to the manual hubs anyway and forget about ever having another hub problem. However a bad hub would not affect the engagement into low range. If you had a bad hub, you would be in two wheel drive low range. Try engaging the 4wd high, drive forward and backward a little, then place the transmission in neutral, depress the fwd low button, and then move the truck forward and backward, repeating a couple of times. Maybe this helps, maybe this doesn't, but I'm extremely skeptical of the switch being bad, I think the problem is somewhere else, but I've been known to be wrong. One quick question. Has your 4wd low range ever worked?
-Dube

 

[Rod Bivens]

The low range works fine when you hot wire the motor to engage it. I just got back from a weekend at Hollister Hills here in the bay area, CA. Once engaged, it works great. The auto hubs are working great also, no problems this weekend. I think the push button itself works fine, now I need to trace some of the wires back to the processor from the motor I guess. Maybee its the processor, but I don't know.

I want the Warn hubs, but don't have the money at this time. I want to solve this problem before upgrading anything. Thanks for the help.
Rod

 

[Barnstormer]

Rod, for what it's worth - I had a similar problem. The control module in the left rear quarter panel (under the seat in a ranger) had fried. My fix was a $35 part from a auto recycler (junk yard).

Good Luck

 

[Nic]

Rod,
I almost fell out of the chair when I came across your problem. I just spent the last 2 days troubleshooting the same exact problem with my 92 explorer. Like you I am looking for a diagnostic test on the electronic shift control module in the left rear. After all the TS I narrowed it down to that. The wiring diagram you were looking for is in the haynes manual (explorer 91-92 pg 12-45. From your writing it sounds like you have the same exact system. Have you gotten any other information from anywhere? Sorry no help for now, If I get anything on my own I'll post it.

 

[Rod Bivens]

I got a good start by going to drbobs web site and ruling out the (more common) transfer case motor problems. It helped me learn enough to be able to hotwire the motor to go four wheeling last weekend. Unfortunately, it didn't fix my problem, but it has helped many people.

Dead Link Removed

It seems that the motor is the main problem, but maybe not in our cases. If I find anything else I'll post it.
Rod