I have a 99 supercab 4x4 and love it. but I'm having some problems with getting the four wheel drive to work. About a week ago I had to change the wheel bearing hub assembly on the drivers side. since then I can't get it into 4x4. IVe removed the automatic hubs and cleaned them to the best of my ability. but nothing works. I have gone under the truck and checked it out while shifted in 4x4. the front driveshaft is locking in, The axle shafts are too. It seems to be the wheel that isn't locking in. I took an air compressor and blew out the vacuum lines leading to the wheels,then jacked up the truck to see what was going on. at one time the wheel seemed to lock in(the cv joint turned with the wheel), but once I gou it down off the jack and tried it on the ground, only the rear wheels would spin. Any help would be greatly appreciated
Thanks for the reply. I'm thinking it's a vacuum leak also. I tried it today and the axle would engage the hubs for about 15 to 20 seconds and then would roll free again. But even with that happening, the rear tires would still spin. Is there anything inside the differential that would cause a problem? And are your axle shafts supposed to be free rolling when you are in 4 x4? I understand when the hubs aren't engaged, like in 2 wheel, they would, but it seems like if you are in 4x4 the front axles would be locked. Onced again thanks for the reply and hopefully someone out there knows what's going on.
FWIW #2 - I have seen "brand new looking" vacume hoses separate between the internal plies and colapse _inside_ while looking to all the world like a brand new hose. Oh, and naturally, if you BLOW through the hose, you won't find that particular problem. About all you can do is change the hose (or tubing) and see if that fixes it.
Hope that winds up helping. Virtually ~nothing~ is worse than a 4x4 that won't 4x4.
Your 4x4 system, like mine, is known as the Pulse Vacuum Hublock (PVH) system, and is engaged as follows:
"...The ['98-'00 Ranger PVH] four wheel drive system is an electronic shift 4X4 system that allows the operator to choose between three different modes. The operator can switch 4X4 HIGH modes at any speed. To engage or disengage 4X4 LOW the vehicle speed must be less than 5 kph (3 mph), the brake depressed, and the transmission must be in NEUTRAL.
The shift motor sense plate, an integral part of the electronic shift motor, informs the generic electronic module (GEM) of the transfer case shift motor and contact plates A, B, C and D position.
The digital transmission range (TR) sensor is located on the LH side of the transmission, and informs the GEM when the transmission is in the NEUTRAL position.
The electronic shift motor is mounted externally at the rear of the transfer case. It drives a rotary cam which moves the mode fork and range fork within the transfer case between the 4X4 HIGH, 4X4 LOW and 2WD range positions.
When the GEM verifies the completion of the transfer case shift from 2WD to 4X4 HIGH (reading the contact plate positions), the GEM will then energize both pulse vacuum hublock (PVH) solenoids (supplying ground for 45 seconds). The PVH solenoid will allow a HIGH flow of intake manifold vacuum to the "wheel end hublocks", engaging the wheel end hubs to the front differential and transfer case to achieve four wheel drive.
When the GEM verifies the completion of the transfer case shift from 4X4 HIGH to 2WD (reading the contact plate positions), the GEM will then energize only one (low vacuum solenoid) of the PVH solenoids (supplying a ground for 10 seconds). The PVH solenoid will allow a "LOW" flow of intake manifold vacuum to the wheel end vacuum hublocks, disengaging the wheel end hubs from the front differential and transfer case to achieve two wheel drive.
The 4X4 shift motor uses a module containing two relays which, under control of the GEM, shifts the transfer case shift motor between 4X4 HIGH, 4X4 LOW and 2WD modes.
The solid state clutch relay is used to activate the clutch within the transfer case which aids in shifting to 4X4. "
It's fixed! I'm sorry for wasting anyone's time with this. The problem, as usual, was something I had done. When I changed the wheel hub bearing assembly I simply removed the old one and replaced it with the new one. Had I taken a little more time I would have seen the little rubber o-rings on the old one which were not on the new one. After racking my brain I took a look at the old bearing and saw the o-rings. So, I pulled everything apart again and put them on the new part. Everything works fine now. I always have something stupid happen. You would think that a part costing $200.00 would be supplied with some .10 cent pieces of rubber. So everyone was right. It was a vacuum leak. Thanks again
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