i have done tons of research on this particular issue and have not locked down a definitive answer, so im hoping to find some clarity.

a year or so ago i got stuck in the snow at my brother in laws house and pushed the 4wd lock button on the tribute and noticed the back tires were not spinning. well being i live in va and we rarely have snow i just dismissed it and didnt really bother thinking about it.

ive recently decided to sell the vehicle and wanted to get the 4wd fixed to get more money. i looked up tons of info on where to start. i checked the number 4 10amp fuse in the panel and it was good. i even put a new one in just to be sure. i found a guy online who walked you step by step on checking voltage and ohms on the 4wd control module and 4wd switch. everything checked out until i came to the connector that plugs into the actual 4wd module. the number 2 or 3 pin and the number 18 pin were supposed to have 10 volts or higher, i read 0. so from what i could understand power wasnt even being sent to the module correctly. well at that point it was a little beyond me how to trace back those wires and find out why they arent sending power.

so today i took i to the mazda dealership and paid them 90 dollars to diagnose the problem. they called me back and said it was the 4wd fuse (which i checked multiple times) and that the tech put it on the lift and all 4 tires spun.

as soon as i got it home i tested it out on a slight hill in the grass.

only the front left tire spun. the right front wouldnt or the back 2.

do i have to have both front tires spinning for it to engage?

now ive seen 2 other guys on here with the same issue. the light comes on. all 4 tires spin when on a lift. but once you put it on the ground only the front tires will spin, not the back. but ive never seen an answer.im at a loss? what do i do? HELP

 

Just to be clear, realize that when the lock button is pushed, it connects the front and rear drive together. It does *not* lock the diffs side to side, so it's entirely possible to have one rear tire spin and not the other. What I mean is that you must observe both rear tires at the same time (like from directly behind). If you happen to viewing from the side and the side you're watching is on a high traction side, that side won't spin. If neither tire spins when there's slippage at either front tire, you do have a problem.

So, assuming that you indeed have no AWD, the rear diff itself could be the problem. The rear diff on this car actually has active clutch packs. Even if the rear drive shaft is turning, there may not be any significant torque transfer going on, so it's different than your standard open rear diff in that regard. On a lift, the only drag on the rear tires is the inertia of the tires themselves, magnitudes less than the drag the vehicle weight sitting on the tires has. So yes, the rear tires could spin on the lift and still have no significant torque transfer at the rear tires when the vehicle is actually on the ground. If the dealer didn't know this; shame on them.

No, you don't have to spin the front tires for the rear to engage. Despite these cars being a relatively inexpensive machine, the AWD is well engineered and seamless in operation. Being based on a FWD vehicle, the front diff is all mechanical and running all the time - the rear output axles receive torque from the rear diff clutch pack at the direction of the AWD electronics.

It could be a mechanical failure in the rear diff itself or an electrical issue. I'd suggest a sharp independent mechanic who could figure this out in 20 minutes.

John