Heated steering wheel wires - POS & NEG?

[jpilk99]

Thanks Purple; I’ve read this post before. It’s for a pre-facelift setup. Very different than mine.


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[purplecty]

Thanks Purple; I’ve read this post before. It’s for a pre-facelift setup. Very different than mine.


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Yeah sorry... I took my heated wheel out for an e39 facelifted sport wheel... This is for an e46 maybe similar?


Watch "Pt. 2 BMW Heated Steering Wheel Retrofit Slip Ring Discussion" on YouTube
https://youtu.be/YW0MtuBSrYw

https://www.bimmerfest.com/forums/sh.../topics/436450

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[jpilk99]

Yeah sorry... I took my heated wheel out for an e39 facelifted sport wheel... This is for an e46 maybe similar?


Watch "Pt. 2 BMW Heated Steering Wheel Retrofit Slip Ring Discussion" on YouTube
https://youtu.be/YW0MtuBSrYw

https://www.bimmerfest.com/forums/sh.../topics/436450

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Thanks again, Purple.

The only problem (for me) is that these videos, DIYs, etc. don't speak to the issue I'm having. I watched that guys video before and it's neat and all... but he wasn't having problems making his setup work. I know I have good POS (switched) and NEG. Slip ring is good. But somewhere along the line of the wiring circuit inbetween the slipring and airbag, and the button pod and then wheel, something is failing.

I've now tested 4 separate heated steering wheels for resistance and they ALL test the same, so I assume that either A). they're all dead and dead the same way (hard to envision that) or B). they're all working as they should.
I've also "tested" 2 separate wiring harness, visually and to the best of my abilities for resistance, and they both seem okay. Like the above, either both are fried or both are working as they should.
Last would be the button pod with the heated wheel button. I've tested 3 of those and ultimately none work - i.e. the heated wheel does not turn on. So again, (and I don't know how to actually test them other than plugging them in and seeing if they'll have their little green light turn on as well as allowing the heated wheel to heat up), either all 3 are dead or they're likely functioning as they should. I will say that all the other buttons on the pod, cruise and volume control work fine.

The next thing I'm going to try is = without the air bag in = plug in the wiring harness, and the the 3 wire connector to the button pod, and see if I can detect 12V (or any V) coming out of the 4-wire connector that should be plugged into heated element of the wheel....

WANH. It's 17 degrees this morning and I wish ONE OF THESE BLOODY HEATED WHEELS WOULD WORK.

[jpilk99]

Did a bunch of testing, with 2 different wiring harnesses, 2 different heated wheels, and 2 different button pods. Same results:

• Can not turn on heated wheel
• 12V coming in on red wire to harness
• Between 4-5V on Blue wire to button pod (blue arrow in picture)
• Same 4-5V on Black with White Stripe to heated wheel (white arrow). Interestingly, when the button pod is plugged in, this drops to 3V
• With button pod plugged in, and Heated Wheel button pushed, the Green arrows shows about 2V (green arrow)

Any ideas? Anyone??

Thank you.

Jay

[acspecialists]

Looking back at the schematic the three black wires and one brown go to the heating element? The brown is negative and has a separate connection? Have you disconnected the wires and tested resistance? The elements are in parallel additionally shouldn't be tested in the circuit. If you disconnect them you could also put power to them and see if they heat up? The 5V is normal control voltage for the other bits.

Try to consider the voltage and power required for heating. A 120 watt heater would require 10 amps at 12VDC, a 120 watt bulb in your house would be one amp. When I turn on my heated wheel its only on for 5-10 mins before my hands start sweating. If the elements are good you could probably find and build a control circuit on the web. It just occurred to me that the third path is a thermal switch that tells the control to shut the power off when/if the wheel gets too hot.

[jpilk99]

Looking back at the schematic the three black wires and one brown go to the heating element? The brown is negative and has a separate connection? Have you disconnected the wires and tested resistance? The elements are in parallel additionally shouldn't be tested in the circuit. If you disconnect them you could also put power to them and see if they heat up? The 5V is normal control voltage for the other bits.

Try to consider the voltage and power required for heating. A 120 watt heater would require 10 amps at 12VDC, a 120 watt bulb in your house would be one amp. When I turn on my heated wheel its only on for 5-10 mins before my hands start sweating. If the elements are good you could probably find and build a control circuit on the web. It just occurred to me that the third path is a thermal switch that tells the control to shut the power off when/if the wheel gets too hot.

Hi acspecialists. Thank you for this post.

"Yes", the 3 black (actually 2 black and 1 black with white stripe) and 1 brown go to the heating element.
"Yes", the brown is negative and ...not sure about the separate connection part. The 3 black wires come out of the little 1" x 2" circuit board within the wiring harness of the wheel. The brown comes directly from the 2-wire connection at the slip ring which brings brown (NEG) and red (POS).
"Yes", I've disconnected the 4-wire connector and tested the resistance in the wheel. However, I don't understand what you mean by, "The elements are in parallel additionally shouldn't be tested in the circuit". What does that mean? I get about 1.5 ohms/amps resistance between pin 1 (black) and pin 4 (brown) while the other combinations of pins 1 through 4 offer no resistance. This is true on the 3 other heated wheels I've tested.
I did disconnect the 4-wire connector from the wiring harness to the ...wheel/heating element and, with the 'brown is NEG' in mind and the fact that the black wire on pin 1 was the only closed circuit, I put 12V to that circuit with no heating of the wheel detected. (It should only take a few seconds for the wheel to start heating and I waited 10-15...). I can't tell from the WDS how the electricity is supposed to flow. If I knew this, that would be a monumental step forward.

Your closing paragraph, while I understand at a high-level, is beyond my ability to do anything with. I don't know about building a control circuit on the web nor, if the 3rd path is the thermal switch, (while I get what that means), I'm unable to do anything with that info :-).

I just wish I knew what voltage, or amperage, was supposed to be on which of the 4 wires into the wheel so I could test the wheel. Additionally, I wish I knew how this wiring harness was supposed to work, how the electricity is supposed to "flow". I know I have 12V coming in on the red wire that goes into the circuit board. I know the brown wire(s) are good grounds. I know I get about 4V on the blue wire coming out of the circuit board into the button pod with the heated wheel button. I know when I press the heated wheel button, that about 2V is coming back on the yellow wire to the circuit board. I know that regardless of the button being pushed, I get about 4 or 5V on the black-with-white stripe wire coming out of the circuit board. Nothing more; no heat, no green light...

Thank you!!!

[racer2086]

Where are you getting your power from? The voltage may not be as important as the amperage.

[jpilk99]

Where are you getting your power from? The voltage may not be as important as the amperage.

Thanks racer. I tapped into this purple wire (see attached).

- - - Updated - - -

Which, now that you say that (about amperage) I recall the parts car I took the 2-wire connector (that goes into the back of the slipring) having that thin gauge green with black stripe wire (thin gauge) that was part of a harness way up into the dashboard. Not a big honkin' purple wire like what I tapped into. Is there a way to measure amperage with my little ohmeter/ammeter?

[racer2086]

The amps are drawn based on the item being powered. You would have to put your meter in-line with the power lead to measure. Most run of the mill meters don't handle more than a couple amps anyway, so you'd blow it out. This is probably not your problem, but how did you tap the wire? I always get scared when I see electrical tape...

At this point, you've tried so many different combinations of things, I'm not sure what to tell you. My gut feeling is that there is something simple we are overlooking that is causing everything to non-function (e.g. something obvious like power or ground that is insufficient). Did you verify the pin numbers in the slip ring that are getting positive vs negative? You should be able to shine a flashlight inside the plug in the slip ring and see two small little numbers that will be labeled 1 and 2.

[jpilk99]

The amps are drawn based on the item being powered. You would have to put your meter in-line with the power lead to measure. Most run of the mill meters don't handle more than a couple amps anyway, so you'd blow it out. This is probably not your problem, but how did you tap the wire? I always get scared when I see electrical tape...


At this point, you've tried so many different combinations of things, I'm not sure what to tell you. My gut feeling is that there is something simple we are overlooking that is causing everything to non-function (e.g. something obvious like power or ground that is insufficient). Did you verify the pin numbers in the slip ring that are getting positive vs negative? You should be able to shine a flashlight inside the plug in the slip ring and see two small little numbers that will be labeled 1 and 2.

Chagrin to say that I just cut, spliced, and taped the POS wire (with fuse) into the line.

I cannot see any numbers in the slip ring that say 1 or 2 for the 2-wire connector that brings POS and NEG to heated wheel, but, I can tell you that I made 100% sure that the pin that feeds the Red wire on the front of the slipring is the one that is getting POS from my wiring. And the other pin that feeds the Brown wire(s) on the front of the slipring is the one getting NEG from my wiring.

I agree that it is likely something simple at this point, but, I just don't know where to look. I've got good (or what I consider good) switched POS and the NEG is grounded well; my testing proves both of these. I have the POS & NEG coming into the slipring correctly and feeding the components inside the wheel correctly; or at least it's correct from everything I can tell. AGain, just not sure what could be wrong. I have not changed the little wiring harness in the wheel. I have tried 2 separate harnesses...

I believe the next thing I could do is go back to the junkyard and try to test one of the cars there with a heated wheel and see if I can get it to turn on. Then, I could swap in my parts (wheel, harness, button pod) and see if they work. And if they do, then the only thing it could be is my POS and NEG...

Thanks as always, racer.

[racer2086]

Here's what I would do at this point to test:

Plug everything in the way it should be, but leave hanging there.

I would put my meter on "continuity test" and put one lead to solder joint on the circuit board where the brown wire is soldered to. Then the other end of the meter gets put on something metal on the car for a sure-fire ground. (We're talking body bolt, dash frame, etc). The meter should beep and read 0 ohms for a perfect ground. I would do that key on and key off. It should be a constant ground no matter what. Then I would move the meter lead to the brown pin of the heating element. That is supposed to be connected directly to ground also.

Then I would keep the meter on that body ground, turn the meter to DC volts, and move the lead at your steering wheel to the solder joint where the red wire attaches. I would do that key on and key off. There should be a solid 12v key on and nothing key off. Here's the challenge: the way you've hooked up the wiring is, to say the least, shoddy, and although you measure voltage, the connection may not be solid and may not feed enough amperage. Because there are electrics in the control unit, it may sense the increased load and shut down before it ever turns on. I only use solder and shrink tubing to be sure of a good connection.

Beyond that, I'm not sure WDS would describe what you should measure on the other pins. That's when I would get a wheel with wiring, control unit, and button pod that are known working and plug that into your slip ring.

[jpilk99]

Here's what I would do at this point to test:

Plug everything in the way it should be, but leave hanging there.

I would put my meter on "continuity test" and put one lead to solder joint on the circuit board where the brown wire is soldered to. Then the other end of the meter gets put on something metal on the car for a sure-fire ground. (We're talking body bolt, dash frame, etc). The meter should beep and read 0 ohms for a perfect ground. I would do that key on and key off. It should be a constant ground no matter what. Then I would move the meter lead to the brown pin of the heating element. That is supposed to be connected directly to ground also.

Then I would keep the meter on that body ground, turn the meter to DC volts, and move the lead at your steering wheel to the solder joint where the red wire attaches. I would do that key on and key off. There should be a solid 12v key on and nothing key off. Here's the challenge: the way you've hooked up the wiring is, to say the least, shoddy, and although you measure voltage, the connection may not be solid and may not feed enough amperage. Because there are electrics in the control unit, it may sense the increased load and shut down before it ever turns on. I only use solder and shrink tubing to be sure of a good connection.

Beyond that, I'm not sure WDS would describe what you should measure on the other pins. That's when I would get a wheel with wiring, control unit, and button pod that are known working and plug that into your slip ring.

Great ideas, racer. Thank you. Will try tomorrow.

Jay

[acspecialists]

If you look at the schematic you can see two heating elements and a squarish symbol. On one side they are all connected to ground, on the other side they are all connected to the board. So each circuit has it's own power and ground, parallel. The squarish symbol is a thermal switch that would be imbedded with the heating elements. When the wheel got too hot it would open and cut power the the elements. Because they are in parallel when checking them they have to be disconnected or the test voltage will use an alternate path. It sounds like you have that part covered.

If you have spares try connecting the elements to power and see if they heat up? As far as a alternative if the elements are good and the switch is good it would not be hard to build an OP/amp to control the elements. The big question mark is the circuit board, we don't have a schematic for that. From what I know of BMW I'm sure it's over engineered. It's probably feed from the outside air temp sensor and then gets feedback from the solar sensor before it checks with the DME to make sure the engine is running and finally the airbag module to make sure you are sitting in the seat. Good luck, just remember when you are at peak frustration you will get it. Then you will have a big smile on you face as you drive down the road with warm hands.

[Timm]

The information from BMW is important:

The steering wheel heater is ready for operation as of terminal 15. It is switched on by pressing the key once on the multifunction steering wheel. The steering wheel heater is switched off again by pressing the key a second time.

Temperature control
The steering wheel temperature is measured by a temperature sensor which is located on the heating element. The electronic control ensures the steering wheel heats up as fast as possible to the specified temperature of 36 °C. The heating capacity of the steering wheel is reduced just before reaching this temperature.


Once the set temperature has been reached, the steering wheel temperature is controlled by a pulse width modulated signal. When the steering wheel temperature is greater than the setpoint, the heating element is operated at 10% of its heating cycle. The steering wheel heater remains switched on and the control is still active.


The heating element and the switch-on monitor are switched off in the event of a break or short in the temperature sensor.


The steering wheel heating system is monitored. The monitoring functions checks whether the steering wheel heats up within the defined temperature limits. The steering wheel heater and function indicator are switched off if there is no temperature increase within this period of time.


Voltage characteristics
The steering wheel heating element is switched off in the event of undervoltage or overvoltage.


The heating element is switched off if the supply voltage at the switch drops below 11.6 V for 5 sec. The switch-on monitor in the switch remains active. The status of the steering wheel heating system is retained.The steering wheel heater is switched on again when the supply voltage increases to above 12.4 V for 5 sec.


The heating element is switched off if the supply voltage at the switch increases to above 16.5 V for 5 sec. The switch-on monitor in the switch remains active. The status of the steering wheel heating system is retained. The steering wheel heater is switched on again when the supply voltage drops below 15.5 V for 5 sec.


​The interesting bit is the voltage - if it drops below 11.6V it will not work - and for that you need the engine running AND decent gauge wiring to it.

[jpilk99]

Great info; both of you. Thank you. More to test!

[jpilk99]

Here's what I would do at this point to test:

Plug everything in the way it should be, but leave hanging there.

I would put my meter on "continuity test" and put one lead to solder joint on the circuit board where the brown wire is soldered to. Then the other end of the meter gets put on something metal on the car for a sure-fire ground. (We're talking body bolt, dash frame, etc). The meter should beep and read 0 ohms for a perfect ground. I would do that key on and key off. It should be a constant ground no matter what. Then I would move the meter lead to the brown pin of the heating element. That is supposed to be connected directly to ground also.

Did this and everything came back perfect 0 ohms.

Then I would keep the meter on that body ground, turn the meter to DC volts, and move the lead at your steering wheel to the solder joint where the red wire attaches. I would do that key on and key off. There should be a solid 12v key on and nothing key off. Here's the challenge: the way you've hooked up the wiring is, to say the least, shoddy, and although you measure voltage, the connection may not be solid and may not feed enough amperage. Because there are electrics in the control unit, it may sense the increased load and shut down before it ever turns on. I only use solder and shrink tubing to be sure of a good connection.

Did this and got 12V at the red wire solder with key on; 0 with off. I also measured V at the blue/yellow/green wires as part of the 3-wire button pod and I get 4V on the blue wire. I ran out of hands/fingers, but, I recall testing this on my bench and when I pressed the heated-wheel button and I got 2 or 3V on the green wire. I also got 3 or 4V on the black with white stripe wire going to the heating element.

I may try digging into the "splice" job, at both POS and NEG and solder and shrink tube...

Beyond that, I'm not sure WDS would describe what you should measure on the other pins. That's when I would get a wheel with wiring, control unit, and button pod that are known working and plug that into your slip ring.

I plan to test on my '03 X5. I'm going to take my wheel and plug it onto the wiring/button pod of the X5. Then I'm going to remove the button pod and/or wiring of the X5 and swap in the wiring and pod of the E38. Depending on the results, I may take the bits from the X5 and move them over to the E38.

After that, I may blow up the car!!!! (Kidding). Thanks all.

[jpilk99]

The information from BMW is important:

The steering wheel heater is ready for operation as of terminal 15. It is switched on by pressing the key once on the multifunction steering wheel. The steering wheel heater is switched off again by pressing the key a second time.

Hi Timm. Is "terminal 15" one of the wires in that big white wiring connector for the ignition? (see picture)? Just curious what terminal 15 means. Thanks.

[TheAngryBear]

Thanks Q!

Many times you will see "terminal 15" or KL 15 referred to in BMW tech info about the ignition cylinder position...below are what the "KL" nomenclature represents.

* O = off
* KL 15 (terminal 15) or "run bus" (ignition switch run position) = ignition position 1
* KL 30 (terminal 30) or "battery bus" (hot at all times) = ignition position 2
* KL R (accessory bus) = ignition position 2
* KL 50 (terminal 50) or "start bus" (ignition start position) = ignition position 3 (start)

Edit: for the more visually oriented



2001 750iL DD74441
Stock

RIP: 2003 540iA Sport GS56111
H&R front springs, Ultimate Cup Holder, Euro Dash & Armrest, Grom, BavSound Stage1

[jpilk99]

Thanks Angry Bear.

So. I went back in to try and complete this upgrade and was surprised to see that the purple wire in that ignition wiring connector which I'm tapped into for POS (see picture) not only has 12V switched power, but, it also had about 10ohm resistance with the battery disconnected. I guess this is why I'm not an electrician, but, I thought the NEG had 0 resistance and any POS wires should be on the other end of the scale, (infinite). Again, while the battery was disconnected, I wanted to confirm that my 2 wire connector for the heated wheel was "in correct working order" so I tested the brown NEG wire and got a lovely zero ohms resistance, but, when I tried the POS green wire, I got the 10ohms mentioned.

Is this my problem?

At this point, I'm considering tapping into one of those red wires, full-time POS, with a 30A inline fuse and getting my power from that. I'm assuming the only downside to this is if I leave the heated wheel on ...it will stay on?

[racer2086]

I would suggest you take my advice above, and add a pin to the ignition switch in the position WDS describes as the factory location. I have a prefacelift car, so things may be different, but I can't imagine they changed the wiring that drastically from 98 to 99 to have changed the power source for the heated wheel. If you don't get your power correctly, you are spinning your wheels.

In regards to your reading, how are you measuring resistance of the power wire? Where is the other end of the meter on, the battery? It doesn't make sense to do that. If you keep your meter on ground, then stick it to the positive pin of your 2 pin connector and read 10 ohms, you are probably reading resistance through whatever device that black/purple wire powers. And anther side note, that is an exceedingly dinky wire to use to supply 10 amps of power for the steering wheel heater. BMW used a thicker wire than that. Don't cause a fire that burns your car up.

[jpilk99]

I would suggest you take my advice above, and add a pin to the ignition switch in the position WDS describes as the factory location. I have a prefacelift car, so things may be different, but I can't imagine they changed the wiring that drastically from 98 to 99 to have changed the power source for the heated wheel. If you don't get your power correctly, you are spinning your wheels.

In regards to your reading, how are you measuring resistance of the power wire? Where is the other end of the meter on, the battery? It doesn't make sense to do that. If you keep your meter on ground, then stick it to the positive pin of your 2 pin connector and read 10 ohms, you are probably reading resistance through whatever device that black/purple wire powers. And anther side note, that is an exceedingly dinky wire to use to supply 10 amps of power for the steering wheel heater. BMW used a thicker wire than that. Don't cause a fire that burns your car up.

Sorry if my brain has dried up, Racer, but, I am confused on 2 points:

Adding "a pin to the ignition switch in the position WDS describes". I'm looking at the WDS and I don't see any reference to where the POS comes from. It just shows a line coming into "Coilspring". Also, I know for a fact, having taken it out of an '01 740 at the junkyard, that the small green with black stripe wire providing POS does not come through the ignition switch. I chased the wire all the way back through the dashboard into a massive wiring harness at the base of the windshield. So, to you other point, "that is an exceedingly dinky wire to use to supply 10 amps of power for the steering wheel heater", I'm using the exact wire BMW uses.

FYI: I tested resistance with NEG on body/frame (great ground) and POS into the big purple wire/pin in the ignition switch connector that I'm tapped into for POS

I'm going to send everyone a bottle of champagne when this gets figured out!!!!! Happy Holidays!

[jpilk99]

SUCCESS!!!!!!!!!!!!!!!!!!!!!

First of all: Thank you to EVERYONE who chimed in on my efforts to upgrade my 01 740iL to a Heated Steering Wheel! Having it work, in 25 degree temps, is heaven. I gotta admit, for all the hours I spent, just seeing the little green light in the Heated Wheel button is ecstasy as well ...during all my failed attempts and not getting that thing to light up.

So, I couple of notes on where I believe I screwed up:

1. Initially, I may have had POS & NEG reversed coming into the slip ring. Big oversight there if in fact that was the case.
2. After digging into my '03 X5, with happy/functioning heated wheel, I realized in needed both the 3-wire (blue/yellow/green) AND the 4-wire (I forget all the colors, white/red/blue...) that also plugs into the button pod with the Heated Wheel button and Cruise.
3. I needed the car running. I may not be 100% correct on this, or maybe my battery isn't strong enough, but, in one of TIMMs posts and possibly others, where ample voltage/amperage were stressed, it occurred to me that most/all of my testing was without the car running.

Who knows, maybe it was something else that was my downfall, but, I believe items #2 and #3 above were the biggies. Bottom line, it works and I'm very happy. Thanks again to everyone.

Anyone want to buy a heated steering wheel or 2? I accumulated a few during my efforts :-).

Best regards and Happy New Year,

Jay

[purplecty]

SUCCESS!!!!!!!!!!!!!!!!!!!!! D

First of all: Thank you to EVERYONE who chimed in on my efforts to upgrade my 01 740iL to a Heated Steering Wheel! Having it work, in 25 degree temps, is heaven. I gotta admit, for all the hours I spent, just seeing the little green light in the Heated Wheel button is ecstasy as well ...during all my failed attempts and not getting that thing to light up.

So, I couple of notes on where I believe I screwed up:

1. Initially, I may have had POS & NEG reversed coming into the slip ring. Big oversight there if in fact that was the case.
2. After digging into my '03 X5, with happy/functioning heated wheel, I realized in needed both the 3-wire (blue/yellow/green) AND the 4-wire (I forget all the colors, white/red/blue...) that also plugs into the button pod with the Heated Wheel button and Cruise.
3. I needed the car running. I may not be 100% correct on this, or maybe my battery isn't strong enough, but, in one of TIMMs posts and possibly others, where ample voltage/amperage were stressed, it occurred to me that most/all of my testing was without the car running.

Who knows, maybe it was something else that was my downfall, but, I believe items #2 and #3 above were the biggies. Bottom line, it works and I'm very happy. Thanks again to everyone.

Anyone want to buy a heated steering wheel or 2? I accumulated a few during my efforts :-).

Best regards and Happy New Year,

Jay

Congrats! Im sure this may be the most satisfying heated wheel retrofit ever after you got it working...

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[jpilk99]

Absolutely!!!


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[Timm]

Thank goodness for that - I though we were going to get to 2019 before it worked!