Here it is, How to repair the most common fault with 4ws and how to do the 4ws alignment.
First of all, my symptoms were different to some, i never heard no loud bang, no warning light on the dash, only symptom there was is crabbing until i pulled out the 4ws fuse which then gave me no symptoms of the 4ws moving at all.
First i recommend testing all voltages on both the 4ws computer and the timing & relay box. Using a multimeter set on 20V with the black lead to the body and red lead to the pin out.
The Timing And Relay Box Is As Follows :
Colour Code.............. Voltage
Check These 2 Pins Have Voltage Approx For 4 to 7 Seconds After The Car Is Off
Colour Code.............. Voltage
4ws Control Unit :
All G........................Approx 12V
If any of those read incorrectly, check all wiring looms, fuses, then if still to no avail replace the units.
If all readings are correct, next step to look at is the 4ws rack itself, from mazda a brand new gasket will cost you about $27.50
The fluid that can be used to fill the rack will be either castrol dextron 2 or 3
4ws Rack Repair
Make sure the car is jacked up on the rear on stands, a jack on each side and a pair of tires or wooden planks for extra safety. Once up on stands there are 6 bolts approx between 11mm and 12mm, undo these to take the protective shroud off the rack.
Next you will need an oil pan to drain the oil out of the rack whilst you take the oil pan off, using an allen key loosen the bottom half of the bolts and the tops half of them on the left side and make sure your oil pan is underneath otherwise it will be very messy. Once all the oil is drained, undo the remain bolts and store them in a container so you know where they all are, these should include a small washer on each bolt. Store the pan and old gasket away so you know where they are, you shouldn't have no real need to damage the existing gasket on there.
Once this is completed your 4ws rack should look like this :
As you can see, the stepper motor is on the right, then you have the piston rod that travels through the bevel gear to the pivot point on the left side. The shaft thats snapped measure the amount of thread left on both ends thats remaining and also once the shaft is out count the number on the inside, as when you get the custom shaft make up you'll need this to get the shaft right. If you forget this important step don't stress as you can work it out later on.
Dismantle the bevel gear using the 2 allen key screw holding it in, as this will need to come out for the 4ws alignment. Also unscrew the shaft from the stepper motor and unbolt the pivot point which will drop out two washers, don't loose them.
Once you have the shaft out and unscrewed from both points, go to your local steel shop and get 120mm long, 6mm diameter bright steel. Shouldn't cost you anything, if it does about $5. Then any good engineering shop can make you the thread, and the break point which makes it a lot more safe, if you do not get this break point installed what can end up happening is the shaft will bend and cause the 4ws to lock up, causing damage on components and also can cause you to crash your car.
Now to do the 4ws alignment you have to get underneath the front of the car and undo the 2 x 12mm bolts holding the steering shaft tot he front steering rack, once these are undone, move back towards the back of the car and you'll see a main mounting point for this shaft, undo those 2 x 12mm bolts and drop the shaft down, and pull it off the front rack. Then you'll need to go to the back of the car and centralise the rack.
As its a little hard to tell, you have two bolts behind the shaft gear wheel in the rack, 1 is to bolt the whole off and the other is the centering bolt as it has a point that locks the steering shaft center. Undo the normal bolt, and turn the shaft so you can see the little centering mark in the center, it is hard to see but its there. Once this mark is in the center screw in the centering bolt and now you'll notice the steering shaft is locked.
Now you can reinstall the new shaft you go made up, screw the shaft in to the stepper motor with the measurement you took eariler on in the stepper motor. Slide the bevel gear back onto the shaft and screw the pivot point onto the other end of the shaft using the measurement u took eariler on. Now you can bolt the pivot point back on and you will have the bevel gear dangling. Now you can install the bevel gear back in.
This following pic shows the bevel gear in the right place, however the shaft is wrongly adjusted for the stepper motor, as it pushes the stepper motor too far in, you can see on the right side of the stepper motor its pushed out of the horse shoe clamp, the right side of the stepper motor should be flush with the horse shoe clamp and not sticking inside or outside of the clamp. If its not set right it can break the shaft again, also if you have your car on and running whilst the snapped shaft is out and bevel gear is not in place you can move the stepper motor by hand and see where center is.
Now once thats all connected and set you can reconnect the steering shaft to the front as long as the front wheels are straight, if there not straight turn them so they are. Reconnect the bolts to the front shaft first, then the main mount behind that after its connected at the front. Remove the centering bolt ( this is a MUST !!! ) and put the normal bolt back in and the center bolt next to it. Now you can test out your car, if all is working thats the 4ws rack fixed and the 4ws alignment done. Now all you have to do is put your new gasket on the oil pan and bolt it back up, fill the rack with fluid via the breather which is in the center of the rack on the top with 1.5 litres i recall from memory. Bolt the protective shroud back on and done. You Just saved yourself $7000 from buying a brand new rack from mazda.
Any questions please ask.