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Discussion Starter #1
My heated seats stopped working after going in to the dealership this is the second time. First time came out and they didn't work. I would hit the button and the lights come on but then they turn off almost immediately. Has this happened to anyone else? I brought my car to Turnermotorsports to get my PSS9 installed and got the conforti shark injector and guess what my seats worked again. Talk about magic. I got BMW to replace my old and missing pixels in the dash, when I went to pick the car up from this job the seat where back to that non-working state again. How do I fix this? The dealership claims again oh you need new seats with new heating elements. I hate dealing with incompetent people. If anyone knows how to fix this without the cost of replacing the seats and everything that would be great. Is there a fuse or something in the dash that controls these?
 

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I've never had an issue with my seat heaters but I don't use them very often either. Are both seats failing the same way? It would be very odd for them both to fail. It would most likely be some component that is common, like the fuse.

There is a fuse for the seat heaters, #32. You access the fuses from the glove box. Two white nobs in the upper front of the box. The open with a 1/4 turn. The fuses tray will drop and there will be a small index that you can pull out to reference. Easy as pie.
 

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Do a search ... this problem has been listed before.

It could be anything from a loose connection under the seats, to a broken (or intermittently failing switch), to a fuse, to an overload condition ... a short or breaking, or nearly broken wire inside the seats.
 

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Had the same problem myself before Xmas and replaced the fuse and all was well! However, it's gone again so I'm wondering if there's a connection or overload problem. But won't be using them from now until next winter anyway, so no big issue. New fuse should do the trick.
 

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Discussion Starter #5
Both are failing the same way, as I said brought to my dealership to have a new gauge display and fix the pixels and it came out with both seats not working again. This ha happened twice and both the day I would pick my car up from the dealership. The second time was when I had heater blower then fan that blows all of the air through the car. This was replaced twice first replacement failed after a few months and was then replaced again under warranty. Both times the car has been picked up with the seats not working. I never had a problem before.


I've never had an issue with my seat heaters but I don't use them very often either. Are both seats failing the same way? It would be very odd for them both to fail. It would most likely be some component that is common, like the fuse.

There is a fuse for the seat heaters, #32. You access the fuses from the glove box. Two white nobs in the upper front of the box. The open with a 1/4 turn. The fuses tray will drop and there will be a small index that you can pull out to reference. Easy as pie.
 

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Both are failing the same way, as I said brought to my dealership to have a new gauge display and fix the pixels and it came out with both seats not working again. This ha happened twice and both the day I would pick my car up from the dealership. The second time was when I had heater blower then fan that blows all of the air through the car. This was replaced twice first replacement failed after a few months and was then replaced again under warranty. Both times the car has been picked up with the seats not working. I never had a problem before.
Maybe a coincidence, but the final stage resisiter is above and to the side of the glove box. The fuses reside above the glove box. It is possible soemthing got jostled, although the fuses should be secure enough.

I would check the fuses first and replace with a known good fuse of the same rating. Someone noted the fuse number above.

If the fuse goes again, there is another issue; something is drawing too much current causing the fuse to blow (which is what it is designed to do).

Also, see if there is anything else on that circuit. If there is something else, easy to check the other items to make sure they are working too.
Regards,
Jerry
 

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Discussion Starter #7
So I did change out the fuse #32 which was blown I had it working all day. My buddy was using the passengers side as well and poof blew the damn fuse. Any cause or way to fix this. Anyway of testing this to find the actually cause? I would seriously forget the sunroof and keep the heated seats any day. Even on those cool summer nights windows down roof open and heated seats on. Any help would be great. I am determined to fix this. I just hope I don't need to replace the seats, because its not really worth it.
 

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Firstly I would not advise this but I have done it with no ill effects.
The fuse for your heated seat is a 25amp fuse, replace it with a 30 amp and see what happens, if does not blow then you know it's not a big problem. If it does then you are going to have to search for the problem because going up to a 35amp is too much.
 

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Does it only blow when you turn on the pasanger seat? If so, try and unplug the passenger seat and see if it still blows the fuse. If it doesnt then it "may" be in the seat, if it does then it may be the switch or a pinched wire.
 

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^Worst Advice

Firstly I would not advise this but I have done it with no ill effects.
The fuse for your heated seat is a 25amp fuse, replace it with a 30 amp and see what happens, if does not blow then you know it's not a big problem. If it does then you are going to have to search for the problem because going up to a 35amp is too much.
Here's a quick lesson in fuses - they are sized to protect the wire connected to them, not the electrical component on the other end. Let me repeat that differently: If you insert a larger fuse you run the risk of melting the jacket on your wire and creating a short ground which in turn, in a car at least, is very likely to cause a fire.

If you don't know how to troubleshoot electronics then take it to someone who does - inserting a larger size fuse, even "just for a moment", is never a good idea unless you are sure the wire can handle it!

Nothing personal Andy, just don't want anyone or their possessions to get hurt.

Doug
 

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Here's a quick lesson in fuses - they are sized to protect the wire connected to them, not the electrical component on the other end. Let me repeat that differently: If you insert a larger fuse you run the risk of melting the jacket on your wire and creating a short ground which in turn, in a car at least, is very likely to cause a fire.

If you don't know how to troubleshoot electronics then take it to someone who does - inserting a larger size fuse, even "just for a moment", is never a good idea unless you are sure the wire can handle it!

Nothing personal Andy, just don't want anyone or their possessions to get hurt.

Doug
Doug I knew you were going to pop up and say that, hense my first sentence. Orginally when I saw this post I was not going to post anything because I knew what I had done was wrong, I was just telling him what I had done.
Like you I don't want to cause any harm to anyone, I am not one of those guys who just posts for the hell of it and misleads others.
 

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Doug I knew you were going to pop up and say that, hense my first sentence. Orginally when I saw this post I was not going to post anything because I knew what I had done was wrong, I was just telling him what I had done.
Like you I don't want to cause any harm to anyone, I am not one of those guys who just posts for the hell of it and misleads others.
I do my best to be predictable :)

I know you weren't trying to get anyone hurt, which is why I tried to stick with just an explanation of what could happen. As I read it again I should note that the "if you don't know how to troubleshoot" sentence wasn't aimed at you, it was directed to the OP since even a 12V battery can cause real issues...

d-
 

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Doug is right (as usual:thumbsup:), but I disagree just a little in the real world applications.

First, my experience is that carmakers are conservative in the wiring and amp ratings. There is a little bit of leeway.

Second, most electrical components have an initial surge when turned on, then their power requirements drop to maintain the appliance.
So, when you hit your seat heater, there is a big initial draw for the first second or two, and then it goes down some. If you go up 5 amps on your fuse rating, you will probably be safe.

But, you still should check out the cause of the original blown fuse, as it could be something as simple as the heating element getting old and inefficient, causing that higher intial draw which is OK, to something serious like a short developing, which is not OK.

So, think up uprated amp as a SHORT TERM solution until the problem is properly checked out.
Regards,
Jerry
 

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Doug is right (as usual:thumbsup:), but I disagree just a little in the real world applications.

First, my experience is that carmakers are conservative in the wiring and amp ratings. There is a little bit of leeway.
I'll agree so far - especially with the part where I am right! :)

Second, most electrical components have an initial surge when turned on, then their power requirements drop to maintain the appliance.
So, when you hit your seat heater, there is a big initial draw for the first second or two, and then it goes down some. If you go up 5 amps on your fuse rating, you will probably be safe.
You's guys is killing me :dunno: Actually, what you really are doing is making me go deep into electrical theory, and I really don't want to...

So... you asked for it!

Wire is rated for a certain amount of continuous current at a maximum voltage. Fuses are rated using the amperage at which they will blow if it is exceeded for a certain amount of time.

For example, a "slow blow" 25A fuse will allow about 35A or so for a short period of time (the startup you refer to). Automobiles typically use slow-blow fuses to avoid nuisance problems during minor surges.

The issue here is that you may have a fault to ground. A fault to ground (meaning a live wire touching the chassis) does 2 things: First, it causes a huge spike in voltage. Second, it causes a huge spike in amperage.

What happens with a huge spike in voltage and amperage? Something melts. It can be the fuse (as intended), or, if you use to large a fuse, it can be the wire.

THAT is why you don't use a larger fuse. And as a side note, there is NO need for a larger fuse when testing. Use a test light (self powered with a small lightbulb) to check for shorts to ground.

But, you still should check out the cause of the original blown fuse, as it could be something as simple as the heating element getting old and inefficient, causing that higher intial draw which is OK, to something serious like a short developing, which is not OK.
Just to clarify, if the heater is getting old and inefficient, it needs to be replaced, not run with more power. If you have a short you need to fix the wire...

So, think up uprated amp as a SHORT TERM solution until the problem is properly checked out.
Regards,
Jerry
I think my opinion on this one is probably pretty clear now :)

d-
 

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Number 32 fuse issue

Hey there - just replaced my number 32 fuse due to the heated seats failing like yours. I turned the car off and left the key in ignition. After replacing the fuse, the seats worked fine but the car would not start. Engine would turn but then die and drained the battery. Was there something I did wrong perhaps by leaving the key in ignition that tripped a safety? It was turned to off position. Anyone have this problem?
 

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Yeah, DONT do that, like he said. I can think of a couple of things to check:

1. Confirm you used the right size fuse. If there is a short in the circuit somewhere the fuse should have blown again and not drained the battery.

2. Was the fuse inserted correctly, i.e., not offset or something like that?

If all is correct, I would think that this points to a short in the circuit somewhere and is why the fuse blew originally. Although, I don't understand why the fuse isn't blowing again.
 

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Hey there - just replaced my number 32 fuse due to the heated seats failing like yours. I turned the car off and left the key in ignition. After replacing the fuse, the seats worked fine but the car would not start. Engine would turn but then die and drained the battery. Was there something I did wrong perhaps by leaving the key in ignition that tripped a safety? It was turned to off position. Anyone have this problem?
Never heard of such a thing. Leaving the key in the off position has no effect on anything except the door chime (if your door is open).

What else did you do while changing the fuse? Something has changed elsewhere in the car - you could pull 20 fuses in that fuseblock without having any effect on the vehicles engine performance...

d-
 

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The issue here is that you may have a fault to ground. A fault to ground (meaning a live wire touching the chassis) does 2 things: First, it causes a huge spike in voltage. Second, it causes a huge spike in amperage.
d-
You are dead right Doug, but I have to bring you up on your terminology .... :1zhelp:

To be specific the short creates an increse in voltage drop. This in turn causes a surge in current, which increases the energy flow rate far above nominal operating wattage for that wire, which, due to the resistance of metal, creates an excess of heat, which in turn melts the fuse and hopefully everyone's still alive, if a little frustrated. Too big a fuse and the wire then starts to heat up, which will melt the sheath, and then your car.....

Ok, I'm running away now! :M5launch:
 

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Okay...problem solved and I am sure I will get some heat on this one.
2000 M5 Owners manual directs you to drop fuse box in the glove compartment, inspect fuses for blown one and remove tool to pull bad fuse. All went as planned. Then to find the correct "replacement fuse" manual directs you to rear trunk compartment right storage area and shows you in a picture where to locate "extra fuses". There I found 7 unmarked slots with what I thought were spare fuses. I pulled the 20amp fuse and repalced in glove box to correct the heated seat problem. All set right?? Well...I pulled the fuse for the Fuel Pump out of the trunk instead of taking from the horizontal spare fuses in the glove box. Guess that would explain why the car would not start!
DUH!
 
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