4x4 vacuum solenoid wiring

Line8 · Dec 30, 2017

Question about 4 wheel drive. My 4 wheel drive didn t work over the weekend. The light on the dash was on but just had rear wheel spin. Jumped out and turned the hubs and all was fine for then. Got home and inspected the pump and the solenoid on the front passenger side. Pump works and I have vacuum. I disconnected the wire connector on the upper side of the vacuum solenoid. When i moved it aside, I noticed it wasnt connected to anything so I pulled it out of the engine area and it is cut. I had the front end rebuilt and I wonder if these wires got clipped.

My biggest problem now is I cannot find where the other end is. Anyone know where these 3 wires go? Ive looked from underneath, from up top. I have no idea! Ive lookedonline and cannot see what I need to see. Seems like it would be so simple to fine the other clipped end. Its about 15” in length where its cut.

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6.0 Tech · Dec 30, 2017

Check inside the fan shroud, seen it a few times....

Line8 · Dec 30, 2017

I just was looking at different pics online of the engine bay and I can see how it loops back and down the shroud. I’ll check that.
Thank you.

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Line8 · Dec 30, 2017

Well, I’m striking out. I see no cut wires on the other end. Where can I find a wiring diagram for that solenoid? Dealership? Maybe that will tell me which wire loom to look in under there. I think it might be within a larger group of wires. I do not see the anything inside the shroud looking from the bottom that resembles where these were cut from.

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Line8 · Dec 30, 2017

Wondering if the solenoid is the last of the line?
From the 4x4 switch, does the line lead to the pump, then the solenoid? Or is there another route that it takes through the 4x4 control module.
Seems like the solenoid might be the last in line.
Im thinking of a work around on this wiring issue. Maybe I just rewire it to whatever is in line prior to it.

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6.0 Tech · Dec 31, 2017

If youre talkimg about not using the solenoid, you dont really have to do anything now. The vacuum solenoid is just for the auto hubs. Before you think you may need 4x4, get out in a dry spot and manually lock the hubs and youll be fine. Otherwise, find the wres and rewire. From the solenoid, the wires go straight down into the large bunch of wires that are held to the lower fan shroud. You may have to take the upper and inner shrouds out to be able to see better, as well as the cold side cac tube.

Line8 · Dec 31, 2017

Thank you for that 6.0. That helps. I have found the loom you mention. I’ll open that up.

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uncool · Dec 31, 2017

One wire is hot with key, a ground and the third is the signal from the switch on the dash.

Line8 · Jan 10, 2018

Thought I would report back findings. 6.0 was correct, it looks like it was pulled into the fan and the fan cut the wires. My guess is when the belts were changed or the radiator was changed the wire loom wasn’t clipped back into its secured area.
Thank you for the direction.

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BigNiner19 · Jan 10, 2018

I need to fix mine as well. Not sure what my problem is as of yet, I just know it doesnt lock the hubs when I turn the switch.

BigNiner19 · Jan 10, 2018

I just did a quick check. The pump on drivers side is working. I have vacuum for sure at the solenoid. Is there a way to check if the solenoid is in fact bad before replacing?

BigNiner19 · Jan 10, 2018

So I did some further testing, but not 100% certain that it gives me my answer, but I am pretty confident. I took the bottom hose off where it connects to the solenoid and connected it to the hose adjacent to it under where the battery is on passenger side (this hose appears to be going down towards the axle/hubs.

I feel that I have bypassed the solenoid function all together and the 4x4 function now works without having to manually lock to the hubs at the wheel.

I could turn the switch to 4x4 and it definitely engaged as you feel it when you make any kind of turn and then back to 2x4 and it would go back to 2wd as normal.

Looks like I need a new solenoid

Rookie question however, if i were to just leave it hooked up bypassing the solenoid, would this just mean the system would constantly be under full vacuum, making the pump occasionally come on and always having pressure on the line? I would assume you wouldnt want this for a long term fix.

Thank you

Line8 · Jan 12, 2018

Yeah I think you found your problem. That solenoid has been a common failure point.
With your vacuum test, I would think it would always be pressurized if you left it that way.

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