Hello,
this is my first time posting on the forum and I am hoping to take advantage of some of the knowledge here.
I have an '06 6MT coupe that I bought earlier this year. It's in decent shape with everything working properly, the exception being the heated seats. There have been a few threads asking about heated seats but I'm not sure they cover my case. I have checked every fuse associated with heated seats, the under-dash heated seat relay, and the switches themselves and their connectors.

I have also removed the driver seat and when I did, the heated seat switch would light when toggled. this only happens when the seat is disconnected and strangely said switch light will turn off again when the passenger switch is also toggled. I located and tested the seats heating circuits with my voltage tester, they show that they are good closed circuits, the power plug the seat connects to is also delivering power when the switch is toggled. When I connected the seat back up, the switch would no longer light and the seat would not heat up. Apparently the electronics to run the seats heaters are only working when the seat is disconnected. All other power functions work as they should.

I haven't used the tester on the leads for the heated seat switches yet to see if they are getting power to begin with, but I'm guess they aren't since they don't light up. when the headlights are turned on the switch icon lights light up with the cars other controls, however. I did notice that the fuse box behind the battery had dried mud spots inside of it as if there had been some moisture, I don't know if that has anything to do with it.

As you might imagine this problem is getting pretty annoying, and temperatures are expected to drop in my area very soon. If anyone knows what else I can try or what I've missed, it would be very helpful, thank you.

 

Yep I was going to say this sounds like a possible IPDM issue, I think there is an internal relay for the heated seats in the IPDM. I know it's in the FSM electrical schematic but it doesn't say where, that usually means an internal relay for the IPDM.

 

Hey thank you for responding! after digging deeper into the IPDM it sounds like you're right, I'm going to give this a try. In case I have to replace the whole thing, do you know a good source for them?

 

I would start by removing it, take a good picture of everything like which relay and fuse goes where. Disassemble the entire thing down to the circuit board, put everything in a bag of rice to dry it out.

Just like drying out a cell phone.

If that doesn't work check your local pick and pull wrecking yards, if not then eBay is my go to for used parts.

 

Hey thanks a lot for the help, a few of my relays had this corrosion, this ones the worst. I took the IPDM most of the way apart and I i'll just replace the whole thing, drying it out got rid of a check engine light though. I think i've found a good one on ebay to replace it with. It's marked as being for 2004-2006 coupes, should i go with a year specific one or will it be the same?

 

I think they had different IPDM models for different years. They all look the same but I guess the circuitry inside is different. Ive seen a few threads of people swapping out their IPDM and that would cause their wipers to run continuously.

So I guess make sure u get the same exact part number.

Also, there is a drain hole under the compartment where the IPDM sits. The hole isnt too big and sometimes gets clogged up by debris, causing water to build up and flood the IPDM. Make sure that hole is clean. Mine had a rubber grommet on the hole. I removed it to make the hole even bigger.

 

I saw that issue with the wipers, seems to be something to do with putting a sedan ipdm in a coupe. apparently the coupes from 2004-06 are supposed to be the same, (according to Ebay dealers) but I won't take the chance. I'll definitely open up that drain, my battery tray was completely full and it was filthy in that part of the bay. I'll have to recommend these fixes to my brother, he has a pristine 2003 brembo packed sport coupe with 78k km (48k miles) that needs the preventative maintenance. Thank you very much, this has all been really helpful.

 

Oh yeah I took a small drill bit and put a few small holes at the bottom of my battery undertray as well. I did have some water in there too…and it barely rains here. Know where to put the holes though cause theres metal under some parts of that battery tray which wont let the water drain out.

 

Before you order up a replacement IPDM you should try just cleaning out the one you have. That corroded relay you can use aerosol electrical contact cleaner MAKE SURE THE CAN SAYS SAFE FOR PLASTIC, spray all that crud off the IPDM contacts, get a new relay, apply a very light layer of electrical anti-oxidation grease to the pins on the relay and plug it in.

The IPDM is actually pretty robust and a minor amount of corrosion like that isn't the end of the world as long as there is metal left, they can be fully submerged, dried out, and keep on working. The contact cleaner will get the crud off, the anti-oxidation grease will keep it from getting worse. The biggest thing like Scorpio said is to fix the drain so it doesn't happen again.