2001 Trooper: Front axle will not engage when I press dash 4x4 switch

I have the same problem (2001 Trooper 118K mi). In the past when this happen (3 X) the dealer replaced the Vacuum Sensor Valves (solinoid valves). These are mounted on the front axle under a skid plate. T avoid paying the dealer $400 again (parts and labor) I found the part on line for $150 shipping and handeling. It took about 1/2 hr to replace. It worked fine for a bout 2 weeks and again will not engage. I'm at a loss as to what else might be causing this issue. It may be one of the vacuum lines, the acctuator or the vacuum tank. I don't want to start shotgunning the rest of the system. I have the same problem (2001 Trooper 118K mi). In the past when this happen (3 X) the dealer replaced the Vacuum Sensor Valves (solinoid valves). These are mounted on the front axle under a skid plate. T avoid paying the dealer $400 again (parts and labor) I found the part on line for $150 shipping and handeling. It took about 1/2 hr to replace. It worked fine for a bout 2 weeks and again will not engage. I'm at a loss as to what else might be causing this issue. It may be one of the vacuum lines, the acctuator or the vacuum tank. I don't want to start shotgunning the rest of the system.

4x4 not engage 4x4 not engage

Tanner78, where did you purchase the vaccum swicthing valve for $150.00? Tanner78, where did you purchase the vaccum swicthing valve for $150.00?

Tanner78, where di you purchase the vacuum switching vavle for $150.00? Tanner78, where di you purchase the vacuum switching vavle for $150.00?

I SOLVED THE PROBLEM FOR FREE, gentlemen...here's how:

YES, as Tanner 78 has said, it was the Vacuum Switch Valves (VSV) (well, T78 said 'vacuum sensor valve' but I''m sure he's talking about the same thing)

The VSV's are tiny little things, one grey and one blue. They are made of plastic and are each about the size of a Bic lighter. They're mounted together on a thin rectangular metal plate which is then mounted onto the front axle, and there is a skid plate that protects them.

Each VSV has a solenoid inside it...a solenoid is an electrically operated device that moves a little internal plunger back and forth. In this case, the plunger sends 'vacuum' to either the RIGHT side or to the LEFT side of the vacuum device that "engages" or "disengages" your front axle.

In my case (as it turned out) the little plungers inside the solenoid of the VSV's must have been plugged up with something...gunk... oil...I don't know, but they were obviously not doing the job.

HERE IS HOW I FIXED MY TROOPER FOR FREE: I cleaned out the VSVs. Simple as that.

HERE IS HOW TO DO IT:

1) Remove the VSV's from the front axle. EASY DOES IT! There are three little black vacuum hoses running to each VSV...they are a pain to remove, and BE CAREFUL because the body of the VSV is PLASTIC and if you break it...you buy a new one. The hoses just slip over the little nozzles...you have to pry them off gently with a straight blade screwdriver. However you do it, remember you're dealing with a tiny plastic part. ALSO, be sure to note where the hoses came off! LABEL THEM!

2) ELECTRICAL: You also have to remove a little electrical wire from each
VSV...the wire connects with a colored plastic plug (one grey, the other blue). There is
a TINY brass wire that locks this plug onto each VSV. You have to
GENTLY pry this wire up to let it clear the little locking lug. It's a pain...make sure you have good light. And again, it's plastic, so take it easy.

3) When you have the hoses and wires off, remove the little nuts that hold the thin metal plate to the axle. The whole assembly...which is about the size and weight of a pack of cigarettes...will come right off.

4) Remove each VSV from the metal mounting plate.

5) Where the electrical wire connects to the VSV, you will see there are two 'spades', or little brass ears where the plug went on. You need to get two little jumper wires with tiny alligator clips on each end, because you have to apply battery power to these VSVs to test them.

6) Hook up the jumper wires to the spades on the VSV, then place one clip on the negative post of your battery and one on the positive. If the VSV is working, you should hear a very tiny CLICK from inside the VSV. You might have to hold it right against your ear.

7) If it makes a click, it's working OK. Test it a few times.

8) If you get NO click, the plunger inside is plugged, and you need to clean it out.

9) Use a SOLVENT BASED electrical cleaner and spray it into end nozzle of the VSV. CAUTION: Do NOT use a greasy spray like WD40 or anything like that, or you will gum up the VSV and it will be useless. Make sure you use a solvent based spray that completely disappears when it dries. Spray some into your hand and let it dry...there should be NO residue or oil on your hand at all.

10) Now it's a matter of 'spray and shake' and hooking up the wires to the battery to listen for the CLICK. Spray the cleaner into each of the nozzles...be generous with it... If you have some compressed air, shoot that in too...just get the gunk out. You might not see a huge pile of **** come flying out...we're talking about a small device here.

11) If you get to the point where each VSV makes a nice, clear CLICK every time you apply the battery power, you're done. Reinstall everything and it should work. MINE DID! First try...the front axle engaged, and it works fine months later.

GOOD LUCK DUDES


I SOLVED THE PROBLEM FOR FREE, gentlemen...here's how:

YES, as Tanner 78 has said, it was the Vacuum Switch Valves (VSV) (well, T78 said 'vacuum sensor valve' but I''m sure he's talking about the same thing)

The VSV's are tiny little things, one grey and one blue. They are made of plastic and are each about the size of a Bic lighter. They're mounted together on a thin rectangular metal plate which is then mounted onto the front axle, and there is a skid plate that protects them.

Each VSV has a solenoid inside it...a solenoid is an electrically operated device that moves a little internal plunger back and forth. In this case, the plunger sends 'vacuum' to either the RIGHT side or to the LEFT side of the vacuum device that "engages" or "disengages" your front axle.

In my case (as it turned out) the little plungers inside the solenoid of the VSV's must have been plugged up with something...gunk... oil...I don't know, but they were obviously not doing the job.

HERE IS HOW I FIXED MY TROOPER FOR FREE: I cleaned out the VSVs. Simple as that.

HERE IS HOW TO DO IT:

1) Remove the VSV's from the front axle. EASY DOES IT! There are three little black vacuum hoses running to each VSV...they are a pain to remove, and BE CAREFUL because the body of the VSV is PLASTIC and if you break it...you buy a new one. The hoses just slip over the little nozzles...you have to pry them off gently with a straight blade screwdriver. However you do it, remember you're dealing with a tiny plastic part. ALSO, be sure to note where the hoses came off! LABEL THEM!

2) ELECTRICAL: You also have to remove a little electrical wire from each VSV...the wire connects with a colored plastic plug (one grey, the other blue). There is a TINY brass wire that locks this plug onto each VSV. You have to GENTLY pry this wire up to let it clear the little locking lug. It's a pain...make sure you have good light. And again, it's plastic, so take it easy.

3) When you have the hoses and wires off, remove the little nuts that hold the thin metal plate to the axle. The whole assembly...which is about the size and weight of a pack of cigarettes...will come right off.

4) Remove each VSV from the metal mounting plate.

5) Where the electrical wire connects to the VSV, you will see there are two 'spades', or little brass ears where the plug went on. You need to get two little jumper wires with tiny alligator clips on each end, because you have to apply battery power to these VSVs to test them.

6) Hook up the jumper wires to the spades on the VSV, then place one clip on the negative post of your battery and one on the positive. If the VSV is working, you should hear a very tiny CLICK from inside the VSV. You might have to hold it right against your ear.

7) If it makes a click, it's working OK. Test it a few times.

8) If you get NO click, the plunger inside is plugged, and you need to clean it out.

9) Use a SOLVENT BASED electrical cleaner and spray it into end nozzle of the VSV. CAUTION: Do NOT use a greasy spray like WD40 or anything like that, or you will gum up the VSV and it will be useless. Make sure you use a solvent based spray that completely disappears when it dries. Spray some into your hand and let it dry...there should be NO residue or oil on your hand at all.

10) Now it's a matter of 'spray and shake' and hooking up the wires to the battery to listen for the CLICK. Spray the cleaner into each of the nozzles...be generous with it... If you have some compressed air, shoot that in too...just get the gunk out. You might not see a huge pile of **** come flying out...we're talking about a small device here.

11) If you get to the point where each VSV makes a nice, clear CLICK every time you apply the battery power, you're done. Reinstall everything and it should work. MINE DID! First try...the front axle engaged, and it works fine months later.

GOOD LUCK DUDES