Sorry for the long thread, but I hope to capture most of the information up front.
I had a left rear alignment problem that I could not correct even with a new R53 left rear trailing arm and new bushings. I decided to convert to the R56 aluminum trailing arms because they supposedly had better toe and some comber adjustments. I got a conversion kit from a vender and installed them. The three lights were on when I took it to the dealership (they had a special on alignments that month) They got the physical alignment correct, but the lights were still on.

So here is a laundry list of things that have been done by them (and me) include
Dealership ran the diagnostics and found the right rear wheel not sending a signal.
Dealership replaced the sensor (swapped them from left to right, then replaced with new sensors.
Dealership replaced wheel bearing hubs with BMW/Mini branded parts.
Dealership said ABS unit was bad.
I sent it off to an online ECU repair place. I was told it was bad and needed replacing. I bought a refurbished one from them.
While I waited on the new module, I disconnected the battery, disconnected the ABS module. and disconnected the right rear sensor.
I shorted terminals 42&43 and then back probed the wires and got .6 Ohms (.1 ohm was a direct short between the probes)
I un-shorted terminals 42&43 and tested the wires to ground and found not shorts to ground.
When I got the module back, I reconnected everything and it still showed the right rear had no signal.
I back probed and got 12.7 volts at the connector with only a slight voltage change when the hub is turned.

Have any of you guys made this trailing arm change and had this issue?
I have less than a month before I need a safety inspection and am trying hard to get this fixed before that deadline.

Any help would be appreciated.

Jeff

 

What wheel speed sensors did you originally use in the the trailing arms and what sensors did the dealer replace them with?

I’ve had all the parts for a while but they’re still waiting for installation. From all I’ve read, the R56 sensors are not supposed to work and the R53 sensors should be used. However, they are smaller in diameter so an adapter sleeve should be used. Centering the 1st gen sensors in the hole is supposed to work but that will probably let a lot of dirt in and cause issues in the future.

 

RB-MINI

Thanks for the info.
I used the used R56 sensors as supplied with the rest of the kit, Originally one worked and one did not. I now have an old R56 sensor on the left rear that works and a new R56 sensor on the right rear that does not. I thought about it this morning and realized that I did a wire probe on the module side of the connector. I wonder if the connector could be bad. I will make a jumper and run the right hub through the wiring for the left hub and see if it shows movement.

Also, I forgot to mention that I checked the spacing from the face of the hub to the end of the sensor from the distance to center of the hub and the sensor on both sides and they are the same.

Jeff

 

Not sure how the sensors line up physically, but I would try using the R53 sensors if you still have them. Also, are you still using the original 12mm hubs/wheel bearings or the 14mm?

Posts aren’t alway clear or complete, but I’ve seen posts that say the R56 sensors work, and other that didn’t until they used the original sensors. I was under the impression that something was different with the sensor signal due to the sensor itself, or the combo of the hub and sensor. Not sure if the new sensors worked only with very late production R53 and equivalent R52’s since they used the same 14mm hubs as the R56, or if some of those were mixing R56 sensors and 12mm hubs. It could also be something in the ECU or BCM firmware after a certain date.

 

And that is the rub.
The left side has R56 trailing arms and R56 sensor, and it works fine. It is the right rear that does not work.
I swapped the hubs and then the sensors and the left side works with both hubs and both sensors, right side does not work with either hub or sensors
I made another test for voltage on the sensor side, so I know the right rear connector is good.
I made a jumper and ran the left wheel hub to the wiring for the right hub and it works. I ran the jumper from the right wheel to the left wiring and it did not work.

So the only thing left is the training arm itself that is causing the problem. I have ordered a new R53 rear sensor. I will fashion a way to mount it and then I will report back tomorrow.

Jeff

 

OK, so after repeating each diagnostic test again, (swapping hubs, swapping R56 sensors, tracing wires, getting 12.7 volts at the connector, getting a rebuilt ABS module, using R53 sensors) I still could not get the right rear to so any signal.

Well, I took a chance and bought a used R53 ASC module and pump and swapped out the rebuilt (with life time warranty) unit and now I have a signal from all four wheels. I still have a few things before I can get it on the road again, but for now I think I solved it with a new ACS module.

If there are more problems, I will let you know.

Jeff

 

I was just looking at a pair of R56 sensors that I had exactly the same experience with, one side would always work but not the other 😂. I ended up fitting the R53 sensors. For me, when travelling under 30mph, no fault was being flagged.

They both seem to be behaving the same as one another in terms of impedance and passing a magnet over the sensors.
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The phenomenon continues.

 

I did the R56 rear arm conversion, used R56 sensors with no issues. Only thing I changed was the wheel bearings/hub so the wheel nuts matched the front.

 

I wonder if working R56 sensors depends on pre or post facelift. What year is your car?

 

Mine has a build date of October 2005.
I didn’t touch the sensors on the 56 arms, just plugged them straight into the R53 loom, no issues.

 

I am having the same problem with the right rear wheel speed. I've swapped everything including the ABS electronic module and nothing. Even jumpered them to the left side.

So did the original poster try a 3rd module (used) and it worked? My family has converted 3 Gen 1s to Gen 2 rear suspension and only 1 had a problem and it needed a module.