1995 Explorer 4wd sensor

[RustyRelic]

My 4wd on demand actuator crapped out a year or so ago. I learned that 1995 was the last year they used it, going to a different design after that. The dealer said it was out of stock at Ford. He said if I could find it he'd install it for 100 bucks labor, and gave me the part number. I tried combing the internet for used parts dealers to no avail. If the 4wd can't be salvaged I'll have to give up on the old bus, which I love. Here in northern Illinois, it is darned near essential. And when it was working, I could practically climb trees with it.

So - anybody have a suggestion for sourcing? Obviously a junked 1995 Explorer or ranger with 4wd is the source, but there aren't junkyards around here to prowl like I did as a kid in the South. So I need to find the cadaver and someone willing to remove the part and ship it to me for a reasonable fee.

And

Anyone have any experience with rebuilding this component?
If I remove it to try to repair it, can I drive without it?

As I understand it, it is a solenoid that kicks in the 4wd, triggered either by the slip-sensors or by the "4wd low" switch. Since neither method activates it, I am assuming the solenoid is dead - or perhaps just seized up and salvageable.

The old bus is a rust bucket - the entire underside is a mess - and it will probably collapse in a few years, but I'd like to nurse it along a couple more years before springing for a successor. Everything above the rocker panels is in super shape. Leather interior, great sound system. And I just like it!

 

[FR-425]

Do your 4wd Indicator lights flash when you first turn on the key indicating self test?

If no lights then the 4x4 control module is bad.

Check the fuses first of course. You did check the fuses yes? and relays

It is located in the passenger side kick panel.

In that case you'll be need'n one of these:

http://www.ebay.com/itm/like/350612462291?lpid=82

Or junk yard. Oh yeah no Junk Yards. oops.

Pull the old one first to get the right part #

It's gonna be different than the non-auto versions.

And when you pull the kick panel you might just find a loose connection or as you mentioned corrosion.

So you may be able to hit the connectors with some circuit cleaner and whuala!

To get you through the winter though you can remove the t-case shift motor and shift it to 4HI manually and leave it there until summer. Then manually shift it back to 2wd.

You can move the shift fork by hand then turn the electric motor by hand to line it back up to the shift fork and put it back on.

 

[RustyRelic]

Thanks!

Both 4wd indicator lights flash when starting. Also, they light up consistently with the control knob positions. I assume the dealership went through the diagnostics when they told me the issue was the vacuum pump and gave me the part number for it.

I gather from what you wrote that the motor shifts a lever among three positions, and if I remove the motor I can shift it manually and leave it. That sounds good - but just to clarify...

If I put the lever in the 4wd high position, the 4wd on demand feature will work without the motor involved? That is, whatever senses slippage and engages the front driveshaft
would function? Or might it be that THAT is what is faulty? Is that the vacuum pump? If moving the lever will do it, then it is less convenient than the older method wherein one had to engage the hub locks, but not by much. Just requires getting under instead of kneeling on both sides. And it will be better in that it will still have the "on demand" feature rather than all four locked in permanently.

 

[FR-425]

Ok my bad, didn't quite catch the "auto 4wd" part

Yes, once you switch it manually it will remain in 4x4 High, no auto function.
You will be in 4x4 High all the time.

The position sensor will be in the 4x4 high position and the control module will behave accordingly.

NOTE: SWITCH THE DASH SELECTOR TO 4X4 HIGH FIRST. or it may attempt to shift back to auto mode.

And disconnect the battery first. don't want the actuator grab'n your fingies, just in case it is just a loose connection!

Best option is to just replace the actuator and or vacuum pump.

As you pull it apart you may discover the problem. I'd test the vacuum pump manually before buying one and double check all connections and fuses/relays.

Did not know they were vacuum actuated. Learn something new every day.

Makes sense though; an electric motor would be to slow to make it shift fast enough to work well.

 

[FR-425]

Search the parts for sale/parting out section on this forum.

For sure someone has one of these.

 

[RustyRelic]

I have been assuming that what you are referring to as "4wd High" is the "on demand" option. And where you referred to an electric motor we're really talking about the vacuum motor. That was my bad in the original post when I referred to a "sensor." I gather that the "sensor" is something that recognizes the rear wheels have broken loose, by comparing speed to the front wheels, and that this is all electronic; with a decision made by computer, and probably working fine. The sensing is happening, and if I have the switch in "4wd" that SHOULD tell the computer to tell the vacuum-driven actuator to flip the lever and engage the front wheel drive. In that position I BELIEVE the drive system is in the same state as "4wd low" except that the vacuum-actuator will pull it back as soon as it senses no more slip. There is a big warning in the user manual about going over 5 mph in 4wd low. I assume that is because sustained operation in 4wd at speed will fry something.

Thus I am dubious about manually overriding the sensor logic by putting it in 4wd and leaving it there. There is no "4wd high" per se. That would be what is called "all wheel drive" which is now common but in 1995 the "on demand" feature was a big deal versus having to manually engage locking hubs. The drawback to the locked hub method was that when cornering you got a lot of wheel slip - the same thing I saw back when my 4wd low was working and I turned sharply at low speed, leaving skid marks all over the driveway. It was not a big issue because usually I was in dirt/mud when I used 4wd low. But at speed would either be dangerous, ruin tires, ruin the mechanism, or all three.

Anyway, here is what the dealer told me I need:
Need Ford Explorer Front Differential Vacuum Motor part F57Z-4A113-AA

 

[FR-425]

Your selector only has two positions?

4hi & 4low

 

[RustyRelic]

There is 2wd, 4wd, and 4wd low

the 4wd position is the "on demand" option


I never saw the term "4wd high" until I saw it on this site a day or so ago.

 

[FR-425]

No, there is 2wd, 4wd and 4wd low

Your selector only has two positions?

4hi & 4low

OOOOHHHhhhhh KKKKKK!

Shoot I thought it was "2wd" - "4wd Auto" - "4wd High" - "4wd Low"

So you are correct the only option is to repair the servo, pump, what ever.

Are you absolutely sure this thing is "Auto" (on demand) only in 4 high?

I ask because I've never heard of a three position switch being labeled like that. Must be a 95' only thing.

Usually 2wd - 4wd Auto and 4wd Low for three position with Auto 4wd.

And then remove the word "Auto" for normal transfer case. Just like yours is. (2wd-4wd-4L)

 

[FR-425]

Are you as confused as I am now? Yikes!

 

[FR-425]

Rust bucket huh?

May be time to take her out behind the barn, and put her down.

Save the innards for her new sister. .. ...:yelexp:

 

[FR-425]

Does this look like the part you need?

http://www.rockauto.com/catalog/moreinfo.php?pk=3763674&cc=1119642

Have a look at this video: says ALL 95'-98' explorers (same part)

A1 is a sponsor of this sight; you may want to contact Tony.

http://www.youtube.com/watch?v=9ldrtZODxQ8

Tony
SALES 888-844-3383