4WD Problem

[S0r0kiN]

Hi, I can't figure out 4wd for a long time. I have a 1996 Explorer with a controltrack system.
I do not get a control minus from the GEM unit to the front vacuum valves, which in turn do not want to block the front differential. Tell me where to dig? The TC switches to four-wheel drive low ok, checked the valves, they are working vacuum comes to them, "+" comes, there is no control "-" from GEM
Waiting for ideas thanks.

 

[dvdswan]

Welcome to the site.

 

[410Fortune]

The gem doesn’t send a “deflate” signal it can only activate the vacuum solenoid or not activate it

Vacuum applied the center axle disconnect slides to the “locked” position with no vacuum it should spring back to the unlock position.

To get in and out of low range you must be stopped with foot on brake and truck in neutral (not park) or
Clutch pushed in

The 95-96 cad systems were problematic so they went away in 97
I have never had a good “vacuum 4wd” on any vehicle. Chevy, ford, it doesn’t matter vacuum hubs and vacuum actuated 4wd is just a bad idea imo

We often convert Chevrolet front axles to be cable operated and ditch the vacuum stuff I would do similar to my ford.

 

[S0r0kiN]

The gem doesn’t send a “deflate” signal it can only activate the vacuum solenoid or not activate it

Vacuum applied the center axle disconnect slides to the “locked” position with no vacuum it should spring back to the unlock position.

To get in and out of low range you must be stopped with foot on brake and truck in neutral (not park) or
Clutch pushed in

The 95-96 cad systems were problematic so they went away in 97
I have never had a good “vacuum 4wd” on any vehicle. Chevy, ford, it doesn’t matter vacuum hubs and vacuum actuated 4wd is just a bad idea imo

We often convert Chevrolet front axles to be cable operated and ditch the vacuum stuff I would do similar to my ford.

The fact is that the GEM does not want to control the vacuum valves, according to the scheme, a "-" signal should come from it to activate the valves, but it does not do this regardless of whether you are standing with the brake pedal depressed and the neutral speed on. Could this mean that there is a problem with the GEM module itself?

 

[410Fortune]

I will get my 96 book out and study up on the cad system I have never repaired one of these as they were only 95/96 and only v6

Let’s see what we can do to help!
If you have the wiring schematics handy you can post them up too

 

[EB4X]

You might want to message Pete here, he's had to fiddle around with our 95-96 control-trac system and has tech manual on it...

Pete Deering

www.explorerforum.com

 

[Pete Deering]

Hi, I can't figure out 4wd for a long time. I have a 1996 Explorer with a controltrack system.
I do not get a control minus from the GEM unit to the front vacuum valves, which in turn do not want to block the front differential. Tell me where to dig? The TC switches to four-wheel drive low ok, checked the valves, they are working vacuum comes to them, "+" comes, there is no control "-" from GEM
Waiting for ideas thanks.

?1I do not get a control minus from the GEM unit to the front vacuum valves,
Answer 1
I am assuming you a ground.
The connectors on the solenoid valves on the pass side rad support. Each have a constant 12 volt power from the fuse box on the interior fuse box by driver door.
Turn your key on, engine off, switch the selector switch into 4H. Connect a volt meter or test light. One leg too battery ground and the red leg too each pin of the two wire connector. Do you have power on one pin? The other pin on the connector is a ground, which is switch by the PCM. That should off ,a open.
?2. turn do not want to block the front differential.
The solenoid valves on the Rad support, engage( valve #1), and disengage (valve #2).
Start the engine, switch in 2W, do you have vacuum in one of the hoses? Yes or No. One hose is the source vac and the other is the hose to the front diff actuator.
3. You can test the solenoid valves by providing 12v and a ground to the valve pins. The valve is a coil. Open( power) or closed ( no power).
4. Need too check if vacuum is passing thru the valves.
5. If it all check out, then go too the front diff actuator valve and check for vacuum there.
6. Check the actuator valve

 

[Mbrooks420]

Isn’t there a bolt in option that just replaces the actuator and makes it a live axle, like it should be anyways?