[ashlez]

Originally Posted by M_Bimmer

The LRE you have is working...so now after doing all this today, when you plug the steering heater element back into the LRE, the "short" shows up again?

Is the LRE the correct controller for the steering wheel?

Same error code when I plugged it back in. LRE is the correct controller for the steering wheel yes (and also for my chassis).

[ashlez]

Originally Posted by GrabacrOne

Sorry, I missed your messages on the thread.

The circuits for both the heating element and the thermistor appear to be fine - when I had issues with broken circuits, they would fail continuity tests with resistance on the order of milliOhms if anything at all.

I would imagine the resistance values to be the same for all wheels, but perhaps the expected values are higher for F8x. You mentioned the wheel was refinished, do you know if the original wheel was overwrapped with Alcantara or if the leather was removed first? Coby Wheel (who did this for me) mentioned that this could risk damage to the heating element pad and as a result, he only overwraps the original wheels. It is possible the wires are damaged or the heating element/thermistor lines are touching - these wires are very thin if you peel back the leather covering.

Also, is the steering wheel control module new as well, and is the correct one for your chassis (confirmed on RealOEM)? This part changed among different platforms and is unique even between pre-LCI/LCI.

Thanks - useful information.

The leather was removed first but it was an exchanged wheel, so not originally my heated wheel as I did an exchange for my non-heated to a heated. It's entirely possible that it was damaged during the re-trim but also possible that someone did an exchange for a re-trimmed wheel because they knew theirs wasn't working and I got their broken wheel!

Anyway - have spent some more time on this over the last couple of evenings. I sourced a replacement heated wheel from a 2018 F3x with only 9000 miles on the clock. I checked the resistance of the heating element and it was 2.4 Ohms, which is bang on spec. Swapped it over and it works absolutely perfectly. LED light stays on, message appears in the cluster, and the wheel heats up.

I was also doing some more research online and I found a post for a different vehicle manufacturer where someone had reverse engineered the LRE module. They established that the module senses the current load and will not latch to ON unless it's within spec, so I suspect that's what the BMW module is doing.

https://www.cadillacforums.com/threa...tions.1090290/

Basically - if the heating element is out of resistance spec then it will not will function. Doesn't have to be a complete short or an open. High or low resistance will do it.

[Jacebror]

Originally Posted by M_Bimmer

I would not assume that your steering wheel expected values would be the same as the F10, but if you are saying ISTA states the "out-of-circuit" resistance of your heating element is supposed to be between 2-3 Ohms, and you are measuring 6 Ohms, then this is out of family...BUT...this measurement is neither an open nor a short in the steering wheel heating element....

I do not know the construction of the heating element in BMW's steering wheel, but there is an explanation that would give you 6 Ohms (2x) over the spec...if there are two parallel heating element paths, each 6 Ohms, then together, they'd measure 3 Ohms [R(total) = (R1*R2)/(R1+R2)]...and to get 6 Ohms, one resistance paths has an open. But if there is only a single resistance path in your heating element, then the only way for it to be 2x the expected value, is that the manufacturer of your steering wheel used a different heating element or type (carbon fiber is often used now, instead of "copper").

A quick way to test your setup is to remove the heating element pins from your white connector on the steering wheel right before it goes into your steering wheel leather, and then connect PTC sensor to your module, thus completing the PTC circuit....the thermistor error should go away, and now you should get an error of an "open" in your heating element. If you still get a short, your control module has the short in it...the FET inside the control module for your heating element may have failed.

[Edit: "out-of-circuit" means that a component is not being influenced by other components in the circuit.......by unplugging your steering wheel heating element from your controller, your steering wheel heating element is now "out-of-circuit", while measuring the heating element resistance while it is still plugged into the controller would be an "in-circuit" measurement. "in-circuit" measurements may not yield the same value as "out-of-circuit" values.....]

I know this is an older post.
With the testing of resistance in the steering wheel give an indication if the element is going bad? Cuz mine was running extremely hot, to the point where I had to turn it off cuz I couldn't touch it. Then after a couple weeks of that it stopped working. Turns out the controller module failed and it looked like it had been overheating, browned connectors. So now I am worrying that the element may be weakened and will fail.

[M_Bimmer]

Originally Posted by Jacebror

I know this is an older post.
With the testing of resistance in the steering wheel give an indication if the element is going bad? Cuz mine was running extremely hot, to the point where I had to turn it off cuz I couldn't touch it. Then after a couple weeks of that it stopped working. Turns out the controller module failed and it looked like it had been overheating, browned connectors. So now I am worrying that the element may be weakened and will fail.

...and you most certainly could use this feature in MN.


The controller failure can be explained if it's been asked to drive the heating element greater than it's 100% design intent. A very common failure mode for controllers.

The heating element typically fails open, so I would not assume that your heating element failed, and given that your heating element worked while the controller worked, it's unlikely it has failed due to an increase in current.

I would definitely be suspect of the following two:

1. Bad thermistor reading by the controller due to a bad thermistor
2. Bad thermistor reading used by the controller due to a bad controller

#1 above can be checked doing a resistance check (see earlier posts). If #1 returns a good value, you can assume that the controller was the root cause and the failure mode.

The controller is the cheaper element in the system, so you go this route, and after installation, during the test stage, if the heating element is too hot, immediately save the Controller by "stop using it" before it burns up, then start looking at the thermistor.

Keep us appraised.