[GrabacrOne]

I'm trying to retrofit a heated steering wheel in my car but I can't get it to heat up. I already had LDW so I replaced the steering wheel control module with one including heating (part no. 61317848640), got the steering column switch to activate heating (part no. 61319188878), and the heated steering wheel. I added 248 to my VO and VO coded SZL and FRM. The switch works and the cluster shows that heated steering wheel is activated but the wheel doesn't heat up.

Checking for errors, I get the code C9AC09: FEHLER_STATUS_KONTAKT_NTC_LENKRADHEIZUNG_LIN: TEMPERATURE SENSOR INTERRUPTED in the Switch Cluster SZL module. It seems that the resistive temperature sensor is having an issue.

The steering wheel electronics module is brand new and the other functions, such as the steering wheel controls, the paddles, and the lane departure vibration all work like normal so I don't think the issue is in the module. Anything I should check?

TIA!

[M_Bimmer]

The temperature sensor converts the heating mat temperature into an electrical variable (resistance). A variable resistance with a negative temperature coefficient (NTC) is used.

The hotter the NTC, the lower its resistance. The resistance readings over a given temperature range is non-linear...but on the cold side should be in the hundred's of KOhms (e.g. 200KOhms) vs on the high temp side should reduce to 10KOhms (please note the actual resistance numbers should not be used, rather the magnitude only)

I'd say that if you are measuring Mega-Ohms on the NTC leads, your NTC sensor within the wheel is bad...and requires a new steering wheel.

[GrabacrOne]

Originally Posted by M_Bimmer

The temperature sensor converts the heating mat temperature into an electrical variable (resistance). A variable resistance with a negative temperature coefficient (NTC) is used.

The hotter the NTC, the lower its resistance. The resistance readings over a given temperature range is non-linear...but on the cold side should be in the hundred's of KOhms (e.g. 200KOhms) vs on the high temp side should reduce to 10KOhms (please note the actual resistance numbers should not be used, rather the magnitude only)

I'd say that if you are measuring Mega-Ohms on the NTC leads, your NTC sensor within the wheel is bad...and requires a new steering wheel.

Thanks for the reply. I originally tested within the 200 Ohm range because I thought resistance was supposed to be much lower ~30 Ohms. But I just retested all the way up to the mega-Ohm range and couldn't get a reading.

[Nickco43]

My car did not have a vibrating steering wheel from the factory so I had to change out the clock spring in addition to wiring for power and ground. Once everything was wired in the heating searing wheel just worked. I get a notification on my 6WB when I turn it on and off.

[M_Bimmer]

I get between 9.80KOhms to 9.90KOhms....picture shows 9.84KOhms.

Using a Fluke and very pointy leads.....

[M_Bimmer]

I measured the above value at 64F (17.7C) and assuming that the NTC tries to maintain a steering wheel temperature of around 84C, then the resistance should be down around 8KOhms or below....

You could just repair your steering wheel, and depending on how many stitches you want to redo, if any, you could just attach the new NTC thermistor near the bottom of the steering wheel (leaving the open in the original NTC thermistor where it is - no need to remove)......

One more note, you should make sure your DMM leads are making good contact. I had to dig into the metal sockets to get a reading...initially just showed MOhms...

Hope this helps.

[GrabacrOne]

Originally Posted by M_Bimmer

I measured the above value at 64F (17.7C) and assuming that the NTC tries to maintain a steering wheel temperature of around 84C, then the resistance should be down around 8KOhms or below....

You could just repair your steering wheel, and depending on how many stitches you want to redo, if any, you could just attach the new NTC thermistor near the bottom of the steering wheel (leaving the open in the original NTC thermistor where it is - no need to remove)......

One more note, you should make sure your DMM leads are making good contact. I had to dig into the metal sockets to get a reading...initially just showed MOhms...

Hope this helps.

Thanks! This helps confirm that my NTC sensor may not be working. Yeah, I found I had to dig into the metal sockets on the wire side to get a continuity reading on the heating element wires. But no matter how much I pushed in, I couldn't get a reading on the thermistor. Ambient temp was around 40 F here in Michigan.

I'll look into what I can do. I would rather not undo the stitching.

[M_Bimmer]

I will try and tune my steering wheel heater, to a higher setting, by merely adding in 500 Ohm to 1000 Ohm resistor inline with the NTC thermistor.

I can trick the feedback temperature value by increasing the resistance a bit which will compute a lower temperature than what it really is...this will cause the steering wheel electronics to increase the PWM to a higher PWM value....and remember max PWM value is 1 or (100%)...so there is no fear on my end to make it too hot...

This is merely shifting the NTC's curve.

My Steering wheel doesn't really produce uniform heat, the hottest part in at the 12 O'Clock position, and the lower portion of the steering wheel is the coolest..where on my F85, the steering wheel heat is pretty uniform 360 degrees around the steering wheel. I think the heating mat's used are different...but maybe other F10 owners can weigh in on their heat uniformity or consistency.

[M_Bimmer]

Originally Posted by GrabacrOne

Thanks! This helps confirm that my NTC sensor is broken. Yeah, I found I had to dig into the metal sockets on the wire side to get a continuity reading on the heating element wires. But no matter how much I pushed in, I couldn't get a reading on the thermistor. Ambient temp was around 40 F here in Michigan.

I'll look into what I can do to repair the wheel or try to get a new one. I would rather not undo the stitching.

If you slave in a new NTC sensor, at the bottom base of the steering wheel, you should get the steering wheel heater to work...it just won't turn off at 84C...since the bottom of the steering wheel won't ever get to that temperature, but you could still get it to work...then when too hot, just turn off the heat...

Worth a try for $1.50....another heated steering wheel (even used) will set you back at least $700 (maybe as low as $500 if you can find a deal - but this will be used, damaged, or both)....

Personally, of all of the upgrades on my F10, the heated steering wheel is the most valuable for me....use it every day even here in SoCal (helps with my sore finger joints)...

[GrabacrOne]

Originally Posted by M_Bimmer

If you slave in a new NTC sensor, at the bottom base of the steering wheel, you should get the steering wheel heater to work...it just won't turn off at 84C...since the bottom of the steering wheel won't ever get to that temperature, but you could still get it to work...then when too hot, just turn off the heat...

Worth a try for $1.50....another heated steering wheel (even used) will set you back at least $700 (maybe as low as $500 if you can find a deal - but this will be used, damaged, or both)....

Personally, of all of the upgrades on my F10, the heated steering wheel is the most valuable for me....use it every day even here in SoCal (helps with my sore finger joints)...

Yeah, I think I will try to add a NTC just at the bottom to see if everything else works with this fix - would be worth it for a few bucks.

If you don't mind sharing, where did you get your M-stitched wheel from?

[M_Bimmer]

FCP Euro...lifetime warranty....

Since I plan on keeping my '14 535 for a very, very long time, it was worth paying a little more than Tischer BMW (GetBMWParts)...and don't trust eBay in these types of items...and I hate shiney leather. This is fully matte...

[GrabacrOne]

Originally Posted by M_Bimmer

FCP Euro...lifetime warranty....

Since I plan on keeping my '14 535 for a very, very long time, it was worth paying a little more than Tischer BMW (GetBMWParts)...and don't trust eBay in these types of items...and I hate shiney leather. This is fully matte...

Oh yeah, that's a great idea actually. Would they honor their warranty if you wanted a new wheel if it gets shiny with use?

[M_Bimmer]

Originally Posted by GrabacrOne

Oh yeah, that's a great idea actually. Would they honor their warranty if you wanted a new wheel if it gets shiny with use?

Not sure for shiny leather...but if it "fails", for sure...

If I were in your predicament, I would attempt a full repair..unless you can return your steering wheel...the re-threading is only required of the dark blue thread going back and forth between the light blue thread and red thread....

it would be an easy fix...BUT, before stitching it back up, I'd hook it to up and test that it produces heat....to do all that work to repair the NTC thermistor, stitch it back up, only to find that the heating element pad is defective....

[Unspec]

Originally Posted by M_Bimmer

Not sure for shiny leather...but if it "fails", for sure...

If I were in your predicament, I would attempt a full repair..unless you can return your steering wheel...the re-threading is only required of the dark blue thread going back and forth between the light blue thread and red thread....

it would be an easy fix...BUT, before stitching it back up, I'd hook it to up and test that it produces heat....to do all that work to repair the NTC thermistor, stitch it back up, only to find that the heating element pad is defective....

Doesn't need to fail. You can replace it just cause it's used, which is what makes their lifetime replacement guarantee so good.

As for the uniformity, I have the same thing. 12, 3 and 9 positions are warmest. The rest is just kinda lukewarm. I think BMW figured you'd be putting your hands on those spots the most, and focused on those.

[GrabacrOne]

For closure on this project and to document the retrofit...

As far as getting a good heated wheel, there are a few checks that can be done prior to install. There are 4 pins on the connector: pins 1 & 4 are for the heating element and pins 2 & 3 are for the NTC thermistor used to measure temperature and control heating. You can check if the wheel is functional by testing the continuity over the heating element with nominal resistance of 2.0-2.6 Ohms, and measuring the resistance through the NTC thermistor with a resistance of 10-20 kiloOhms. You will need a multimeter with very thin tips to get a good contact on the connector. Thanks to M_Bimmer for providing nominal values when troubleshooting my first wheel. It seems that heating element or thermistor failure is common (or I just have bad luck!) since two used wheels were non-functional.

The rest of the retrofit went as planned (using the guide from riku2). My LCI F10 had lane change warning (5AG) already so the 12V supply used to power both the LCW vibration motor and heated wheel was already run through the SZL switch cluster module. I had to replace my steering wheel electronics control module with one supporting LCW and heating (248): 61317848640. Note that this part is unique to the M-Sport/M wheels and is different from the module for Pre-LCI or Sport steering wheels. The steering adjustment switch with the toggle for heating needs to be added as well: 61319188878. Everything else was moved over from my M-Sport LCI wheel to the new wheel.

For coding, I added option 248 to my FA and VO-coded SZL and FRM modules and the heating was enabled. In my F10, I get a message in the instrument cluster when heating activated/deactivated.

During this retrofit, I also replaced my center trim from the M-Sport plastic trim to the M leather center trim: 32307846029 and the steering trim rear cover with a slit: 32307848270. The M Performance carbon fiber center trim is also an option: 32302345203. This was well worth it since you get an enamel M badge and the trim doesn't creak like my old M-Sport one did. Also, the foam isolator that goes around the LCW motor is a different shape with the M center trim: 32307850622.

Also, I replaced my stock M-Sport shift paddles with the M DCT paddles. The set of rocker switches are sold completely as part no. 61317847210, but include the electronics as well. From my research, the DCT electronics won't work with the ZF 8-speed auto anyways so I bought just the metal paddle inserts and backing plates off of a forum member in like-new condition, and transferred over the electronics from my current paddles. The process is the same as installing aftermarket paddles, such as from AutoTecknic. These paddles look better and are more tactile than the stock paddles.

Here is a parts list for the retrofit and upgrades:

• Heated steering wheel: 32307846035 (M5/M6) or 32307851231 (M-Sport)
• Steering wheel electronics control module with LCW and heating: 61317848640
• Steering wheel adjustment with heating toggle: 61319188878
• M center trim: 32307846029 (leather) or 32302345203 (carbon)
• M center trim rear cover: 32307848270
• M center trim foam isolator: 32307850622
• M DCT paddle shifters: 61317847210
• Airbag: 32308092725 (M leather) or 32308092724 (M-Sport)

I finally found a working heated steering wheel to use as a core and got my wheel wrapped by Coby Wheel. I was originally planning on getting the M5/M6 M Performance wheel but wanted to add heating as well so decided to go this route. It was wrapped in black alcantara with a red leather center stripe and M tri-color stitching. You can avoid the uncertainty with the wheel heating element by purchasing new but since I wanted to wrap with alcantara anyways, I held out for a functional used wheel.

Overall, I'm really happy with how it turned out. I wanted an OEM+ look and that is why I chose M parts and look. Heating is a bit less intense due to the alcantara material but still pretty warm. Alcantara also feels warmer in the cold and cooler in the sun than leather so that's an advantage.

[ashlez]

Originally Posted by GrabacrOne

For closure on this project and to document the retrofit...

As far as getting a good heated wheel, there are a few checks that can be done prior to install. There are 4 pins on the connector: pins 1 & 4 are for the heating element and pins 2 & 3 are for the NTC thermistor used to measure temperature and control heating. You can check if the wheel is functional by testing the continuity over the heating element with nominal resistance of 2.0-2.6 Ohms, and measuring the resistance through the NTC thermistor with a resistance of 10-20 kiloOhms. You will need a multimeter with very thin tips to get a good contact on the connector. Thanks to M_Bimmer for providing nominal values when troubleshooting my first wheel. It seems that heating element or thermistor failure is common (or I just have bad luck!) since two used wheels were non-functional.

The rest of the retrofit went as planned (using the guide from riku2). My LCI F10 had lane change warning (5AG) already so the 12V supply used to power both the LCW vibration motor and heated wheel was already run through the SZL switch cluster module. I had to replace my steering wheel electronics control module with one supporting LCW and heating (248): 61317848640. Note that this part is unique to the M-Sport/M wheels and is different from the module for Pre-LCI or Sport steering wheels. The steering adjustment switch with the toggle for heating needs to be added as well: 61319188878. Everything else was moved over from my M-Sport LCI wheel to the new wheel.

For coding, I added option 248 to my FA and VO-coded SZL and FRM modules and the heating was enabled. In my F10, I get a message in the instrument cluster when heating activated/deactivated.

During this retrofit, I also replaced my center trim from the M-Sport plastic trim to the M leather center trim: 32307846029 and the steering trim rear cover with a slit: 32307848270. The M Performance carbon fiber center trim is also an option: 32302345203. This was well worth it since you get an enamel M badge and the trim doesn't creak like my old M-Sport one did. Also, the foam isolator that goes around the LCW motor is a different shape with the M center trim: 32307850622.

Also, I replaced my stock M-Sport shift paddles with the M DCT paddles. The set of rocker switches are sold completely as part no. 61317847210, but include the electronics as well. From my research, the DCT electronics won't work with the ZF 8-speed auto anyways so I bought just the metal paddle inserts and backing plates off of a forum member in like-new condition, and transferred over the electronics from my current paddles. The process is the same as installing aftermarket paddles, such as from AutoTecknic. These paddles look better and are more tactile than the stock paddles.

Here is a parts list for the retrofit and upgrades:

• Heated steering wheel: 32307846035 (M5/M6) or 32307851231 (M-Sport)
• Steering wheel electronics control module with LCW and heating: 61317848640
• Steering wheel adjustment with heating toggle: 61319188878
• M center trim: 32307846029 (leather) or 32302345203 (carbon)
• M center trim rear cover: 32307848270
• M center trim foam isolator: 32307850622
• M DCT paddle shifters: 61317847210
• Airbag: 32308092725 (M leather) or 32308092724 (M-Sport)

I finally found a working heated steering wheel to use as a core and got my wheel wrapped by Coby Wheel. I was originally planning on getting the M5/M6 M Performance wheel but wanted to add heating as well so decided to go this route. It was wrapped in black alcantara with a red leather center stripe and M tri-color stitching. You can avoid the uncertainty with the wheel heating element by purchasing new but since I wanted to wrap with alcantara anyways, I held out for a functional used wheel.

Overall, I'm really happy with how it turned out. I wanted an OEM+ look and that is why I chose M parts and look. Heating is a bit less intense due to the alcantara material but still pretty warm. Alcantara also feels warmer in the cold and cooler in the sun than leather so that's an advantage.

Thanks for sharing this GrabacrOne.

I've just completed this retrofit on my F20 M140 (re-trimmed alcantara heated wheel). I didn't previously have LDW or anything else so I needed quite a few parts including the steering column switch cluster, connecting line, steering wheel module, heated steering switch and lower column plastic trim. All these parts were purchased new from BMW except the steering column switch cluster.

I fitted it all today and VO coded option 248. Unfortunately it doesn't work. The LED light doesn't come on even though it says steering wheel heating activated on the dash.

I checked in ISTA+ and it has logged the code "Steering wheel module (LRE), steering wheel heating: Short circuit".

I used a multi-meter on the heating element and NTC thermistor in the wheel. Heating element came out at 6.0 Ohms, NTC thermistor at 19.4 KOhms (7 Degrees C here at the moment)

I've double checked all the connections and everything looks good. Even disconnected the steering wheel module from the switch cluster to test and it showed up another code to say it was missing, so it's definitely getting power.

Do you think the heating element in the wheel is kaput as it's supposed to be 2.0 - 2.5 Ohms isn't it?

[M_Bimmer]

Originally Posted by ashlez

Do you think the heating element in the wheel is kaput as it's supposed to be 2.0 - 2.5 Ohms isn't it?

A short in a heating element will be essentially '0' ohms. Why do you not think it's your LRE? If you leave your LRE plugged in, but leave your steering wheel unplugged from the LRE, what do you get? I predict you get the "short" code as your short is in the module, not the steering wheel

.....but do please let us know.

[ashlez]

Originally Posted by M_Bimmer

A short in a heating element will be essentially '0' ohms. Why do you not think it's your LRE? If you leave your LRE plugged in, but leave your steering wheel unplugged from the LRE, what do you get? I predict you get the "short" code as your short is in the module, not the steering wheel

.....but do please let us know.

I didn't think it would be the LRE as it's a brand new module, but I guess it's still possible. I just tried it again but with the wheel unplugged from the LRE. The short circuit fault code disappeared and different one appeared in its place.

Fault: "030481 Steering wheel module, steering wheel heating NTC contact: Internal fault".
Fault description: "The temperature sensor of the steering wheel heating sends no or implausible values"

Options at this stage

1) Get a 15 kohm resister to emulate the NTC. Repeat the same test with the plug disconnected. See whether the short circuit fault code comes back or is replaced by an open circuit fault code (in which case the LRE is probably fine).

2) Get a dummy load 2 ohm resistor (something like this - https://getawaypower.com/product/2-o...ummy-load-12v/) combined with the resistor to emulate the NTC, and see whether all fault codes then disappear and the car heats the dummy load.

3) Assume the heating element in the wheel is at fault (it's reading 6 ohms instead of 2 - 2.5 ohms as stated in the ISTA documentation).

P.s - the fault description of the short circuit code is "The voltage at the heated area is 0 volts". Didn't share that yesterday but thought worth mentioning. Even so, not particularly descriptive!

Any thoughts? Really appreciate your advice so far.

[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.....]

[ashlez]

Originally Posted by M_Bimmer

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").

Makes sense. The wheel is from an F3x M3. Production date on the wheel is mid 2016.

Originally Posted by M_Bimmer

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.

Just tried this. The thermistor error has gone and the short circuit error did not re-appear. That would suggest that the LRE is okay?

Originally Posted by M_Bimmer

[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 did it out-of-circuit which is what ISTA says (to do it with the plug detached). That's where I got 6 Ohms from (0.006 KOhms on my DMM)

Thanks for your guidance on this. It is really helpful.

[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?

[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.