2001 B4000 4x4 quit working

I have a 2001 Mazda B4000 and the four wheel drive has stopped working. When I turn the electronic control to 4x4 high, nothing happens. No noise, no clicking nothing. Same for 4x4 low. I recently had the truck at Sears to have the tires rotated and aligned, I took it back and they said nothing they did could have caused this. Browsing the forum I see some differing opinions on that. Any help would be greatly appreciated.

I would suggest to follow the wiring harness back as best as you can and check for any loose connections. If it does nothing it sounds like a bad connection. I don't know much about electronic 4x4 but would guess that there is a relay or control module somewhere and maybe check a junkyard for one. Or use an voltmeter to check power along the way using a wiring diagram, which can be found in repair manuals, to check voltage path and how many volts should be where. Just my thoughts, let me know.

Thanks, I 'll check tonight I appreciate the help and will post the results.

I can't see anything loose anywhere, I don't know where the wiring harness for that particular mechanism is.

I think it maybe time to invest in a chiltons book

The rfw controll box is under the left front scuff plate. I doubt if there is anything there you can check. Open the bonnet and find the brake Booster. On the booster there are 2 vacuum actuators. Follow the pipes to the diff in front and check if they are connected. The RFW control box sends a signal to the From the switch to the acutators and onlyu when the front diff is engaged will it shift to 4H or 4L.

Thaks for the reply, here is an update. The 4WD PCM is lodated on the passenger side behind the kickpanel. I checked those connection and they look fine. When I rotate the Knob on the dash that module no longer makes the little click it used to. That would make me think the problem is before it reaches that module. I also noticed the light bulb behind my tachometer has burned out or shorted, possible culprit? It's going to a guy from my chruch tomorrow so hopefully he can help me out while he replaces the front brakes. I still suspect that getting my tires rotated at Sears was not helpful.


The rfw controll box is under the left front scuff plate. I doubt if there is anything there you can check. Open the bonnet and find the brake Booster. On the booster there are 2 vacuum actuators. Follow the pipes to the diff in front and check if they are connected. The RFW control box sends a signal to the From the switch to the acutators and onlyu when the front diff is engaged will it shift to 4H or 4L.

Hey does anyone know where I can download a repair manual or wiring diagram for a 2001 Mazda B4000?

I have taken the truck to two local mechanics, neither was able to diagnose or solve the problem. It goes in to the dealer next Wednesday, hopefully I will be able to post a solution at the end of all of this.

I have a factory manual for the 96 but just the section on the transfer case will probably take me 3 hours to scan.

Here's a load of crap, the dealer said both the Control Unit, and the Change motor are shot. To replace both is $651, and they have to order the parts. What a load, how can you tell if both are shot if you don't replace one at a time? If the contorl unit is broken, how can you test the change motor? :banghead: This sucks.

i know this won't help, but the 4x4 is a constant problem in the ford/mazda b4000 (same truck) where i work. many of them will no longer work. the mechanics suggest just get rid of them.

I am definitely not getting rid of the 4X4, I use it. This guy said he has never seen this happen either which I find hard to believe reading this forum. Does anyone know where I can get the 4X4 control unit where it won't cost $150?

Almost all testing in the factory manual requires a ford scanner to perform the tests. About the only thing you can test for is shorts and opens by backprobing with a dmm.

I recently purchase a 2001 Mazda B4000 and realized that the 4X4 quit working. It has the same symptoms as those suggested in this posting: no clicking sounds, no light on dashboard, nothing. Any help besides those listed here will help. Thanks