4wheel drive problems
- Thread starter miheckman
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labradorrescuer
New member
Whats happening when you engage the 4x4?
jstnjosepht
New member
I would try fixing the 4wd. That should get rid of any 4wd problems.
:tongue:
:tongue:
TheDurk
Elite Member
No, just one. It switches from one to the other.
KidVermicious
New member
Did you read The Durk's post?
The vacuum switching valves turn on and off when the electrical signal tells them to. Look to see if both are being told to turn on at the same time, and go forward or backward from there.
Grenvilleter
New member
OP...first you should determine if your problem is mechanical or electrical. As you verified (I think ?) that both VSV's have vacuum, I'm going to suspend belief for a moment and suggest that you make sure you have mechanical integrity.
On the VSV's you will see some rubber hoses feeding the VSV's with vacuum and a pair of hoses leaving the vsv's and going down to a bellows attached to the front diff. You cannot see the bellows from the top of the engine.
Climb under your truck and remove the front skid plate so you can see the front diff and the bellows I'm talking about.
What is essentially suppose to happen is, the vacuum is applied to EITHER one side or the other of the bellows and it pulls a mechanism inside the front diff that engages or disengages it.
You should hear this happening and feel a little "bump" inside the front diff. Make sure the hoses are not split somewhere and the vacuum is reaching the bellows.
Remove both hoses and then re-attach just 1 hose and listen/feel for a bump. If nothing, remove the hose and place it on the other side of the bellows. If still nothing, you have a problem in the front end and need to re-evaluate.
If you do hear a "clunk",It would help, if you at this point had the truck up on 4 jack stands.
You could actually test out the 4wd mechanical integrity and know the basics were good before you start chasing electrical or electro-mechanical problems.
At this point you will have a better idea of intelligent questions to ask the general community and will get more detailed answers.
There is quite a bit of info already posted in the archives regarding this problem including resistance values of what a working vsv should be. Having an understanding of the working of a DVOM (digital volt/ohm meter) and how to use it is a necessary skill to have as well.
I hope this helps and feel free to ask anything, anytime.
G/L
ray2:
Edit- I bought a '97 LTD as well that nothing on the 4wd system worked. After ensuring the basic "bones" was good by investigating how it was suppose to work and working backwards.
I had access to a "junker" that I knew worked and ended up changing swapping first the vsv's and that got me normal operation in one direction( I could engage 4wd but not disengage without powering down the cct ((key off)))
The 2nd problem was a switch on the xfer case that would not let the vsv pull back to normal 2wd.
On the VSV's you will see some rubber hoses feeding the VSV's with vacuum and a pair of hoses leaving the vsv's and going down to a bellows attached to the front diff. You cannot see the bellows from the top of the engine.
Climb under your truck and remove the front skid plate so you can see the front diff and the bellows I'm talking about.
What is essentially suppose to happen is, the vacuum is applied to EITHER one side or the other of the bellows and it pulls a mechanism inside the front diff that engages or disengages it.
You should hear this happening and feel a little "bump" inside the front diff. Make sure the hoses are not split somewhere and the vacuum is reaching the bellows.
Remove both hoses and then re-attach just 1 hose and listen/feel for a bump. If nothing, remove the hose and place it on the other side of the bellows. If still nothing, you have a problem in the front end and need to re-evaluate.
If you do hear a "clunk",It would help, if you at this point had the truck up on 4 jack stands.
You could actually test out the 4wd mechanical integrity and know the basics were good before you start chasing electrical or electro-mechanical problems.
At this point you will have a better idea of intelligent questions to ask the general community and will get more detailed answers.
There is quite a bit of info already posted in the archives regarding this problem including resistance values of what a working vsv should be. Having an understanding of the working of a DVOM (digital volt/ohm meter) and how to use it is a necessary skill to have as well.
I hope this helps and feel free to ask anything, anytime.
G/L
ray2:Edit- I bought a '97 LTD as well that nothing on the 4wd system worked. After ensuring the basic "bones" was good by investigating how it was suppose to work and working backwards.
I had access to a "junker" that I knew worked and ended up changing swapping first the vsv's and that got me normal operation in one direction( I could engage 4wd but not disengage without powering down the cct ((key off)))
The 2nd problem was a switch on the xfer case that would not let the vsv pull back to normal 2wd.
Last edited:
TheDurk
Elite Member
Just to be clear, if your VSV's are working correctly (vacuum switches from one to the other as you switch from 2wd to 4wd) then there is NOTHING WRONG with your TC switches. The problem is in the diff, either the switch, the actuator, or the gear train itself.
If I misunderstood you, and you tested the VSV's with an external 12v signal, my apologies, and carry on...