04 DTS Cooled Seat problem - fan units or module failure?

11072 Views 30 Replies 7 Participants Last post by BlackLac96, Sep 1, 2009

fleetwood96

Discussion Starter · Jun 22, 2009

Hey everyone, now that it's gotten really hot the cooled seats (both sides) in my 04 DTS no longer work right. They'll work for about 30 seconds then 'click off' as if I turned them off, but the door panel lights are still lit. I cannot get them to come back on unless I turn off the key and turn the key back on.

I see these cars have 2 fan units per seat (one in the seat cushion and one in the back cushion). Both are connected to a "black box" control module. If I unhook both fan units from the module, the module doesn't click off but stays "on" properly. Therefore, I speculate that either all 4 fan units are straining the modules, causing them to turn off in error, or the modules themselves are bad. Also, either one fan unit hooked up by itself also causes the control module to turn off.

Before buying anything, I wonder if anyone has any experience with this problem to know what is more likely the point of failure - the control modules or the fan units. There are no GM part numbers on either the control modules or the fan units, so if someone has any part numbers they can share, I'd appreciate that as well.

Thanks! Doug

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jjm01

· #2 · Jun 22, 2009

The module will click on and off in response to overload. Check the current draw on each of the four units and see if anything is out of line, and zero in accordingly.

Also be sure the input voltage and current is good. Low alternator output, during idle or high electrical will cause the module to click on and off. Since yours seems to be staying off, I'm betting one of the units is bad.

Does the module click off on either side, or just the driver or passenger? If it's only one side, you can try swapping units, until the module stays on.

Joe

JimD

· #3 · Jun 22, 2009

fleetwood96 said:
....Before buying anything, I wonder if anyone has any experience with this problem to know what is more likely the point of failure....

I do not have any experience with that problem on my '04 DTS.

But it will cost you nothing to display trouble codes just in case a clue is lurking in the diagnostic system.

Here is how to display trouble codes (pay attention to your "B" codes);
http://www.cadillacforums.com/forums/cadillac-tech-tips/172511-how-pull-codes-98-04-sevilles.html

fleetwood96

Discussion Starter · #4 · Jun 23, 2009

Both driver side and passenger side are doing the same thing, so I would need a 3rd control module or a 5th fan unit to test the system completely. I did reset all codes stored in the computer, then let the seat coolers fail, and then checked the codes again and saw nothing (no history or current codes were displayed for any subsystem). Also, while not needed, the heat settings do the same thing - they click off after about 30 seconds of being ON.

jjm01

· #5 · Jun 24, 2009

This may sound like a dumb question, but have you replaced the seat filters, both the seat cushion and seat back? If they're blocked, they can cause the problems you're describing. You should also check the exhaust air ducts for blockage and or misalignment.

Has any upholstery work been done on the vehicle? The wrong foam insulation will cause the modules to overload.

The reason I'm asking all these questions is they system is reliable, it's so unlikely both systems would fail simultaneously. I have to imagine you have at least 2 of the 4 units functioning on either side, and can swap 2 good ones until the system works. Either that or the the system isn't getting voltage, or there are bad grounds.

Was the vehicle in a flood?

The modules can be tested. The seat temp sensor in should be above 18,000 ohms and the TED resistance itself should be above 7.5 ohms. None of these circuits should be shorted?

Joe

Ranger

· #6 · Jun 24, 2009

jjm01 said:
This may sound like a dumb question, but have you replaced the seat filters, both the seat cushion and seat back? If they're blocked, they can cause the problems you're describing. You should also check the exhaust air ducts for blockage and or misalignment.

Has any upholstery work been done on the vehicle? The wrong foam insulation will cause the modules to overload.

The reason I'm asking all these questions is they system is reliable, it's so unlikely both systems would fail simultaneously. I have to imagine you have at least 2 of the 4 units functioning on either side, and can swap 2 good ones until the system works. Either that or the the system isn't getting voltage, or there are bad grounds.

Was the vehicle in a flood?

The modules can be tested. The seat temp sensor in should be above 18,000 ohms and the TED resistance itself should be above 7.5 ohms. None of these circuits should be shorted?

Joe

Fart filters? What'll they think of next?

fleetwood96

Discussion Starter · #7 · Jun 26, 2009

jjm01, by "Seat Filters" do you mean on the fan modules themselves? I see all around the outside of the fan unit there is what looks to be a white filter-like material. On the outside it looks nice and clean - no idea about the insides. Also, no idea about the seatback fan units as I haven't taken the seatbacks apart. The bottom modules do blow out exhausted air just fine - they're not blocked, and in fact the seats feel good for the 30 seconds they are on.

I have had each of the 4 fan units hooked up individually to their controlling unit, and the module still turns off no matter which one is connected. The only way I can get the control module to stay on is to unhook both fan units at the same time.

ral1960

· #8 · Jul 1, 2009

I'm having the identical problem in my Deville (both sides), but intermittently. When the interior gets really hot, the seat coolers usually stay on.

I discovered last winter that if I first turn the back heater on alone for several minutes, the cushion heater will then work correctly. Not much help for cold rear ends.

If you find the solution, please post it.
I don't have much faith in my local dealer to fix it (without breaking a few other things).

I'd like to move the front seat back an additional inch or so, but that's another problem.

fleetwood96

Discussion Starter · #9 · Jul 3, 2009

Well, gang, I spent $200+ at the Cad dealership for a replacement control module and guess what? Same malfunction as with the original module - 30 seconds and off it goes. Perhaps I can get them to take it back if they'll look at the car and see what's up. I discovered that if I unplug the small 4-wire connector and plug it right back in I get another 30 seconds of action (same as turning off the key). Otherwise, other than the fan units themselves, I'm at a loss as to why it's deciding to give up.

ral1960

· #10 · Jul 3, 2009

My passenger seat seems to be working OK now. I might try switching parts, one at a time, to see what happens.

If the fan or cooler were drawing too much current, wouldn't the breaker flip off sooner?
Why would the thing work better when it's hot?

jjm01

· #11 · Jul 3, 2009

Yes, the seat filters are on the heating/cooling units themselves... just a white piece of filter material wrapped around. Stretch slightly to unclip from the unit. If the outside is clean, then the they're probably OK.

If you haven't had the seatbacks off, then how could you possibly do a proper heating/cooling unit swap for testing purposes?

It really seems like your voltage input is low, or there is excess current draw. Have you ohm tested the units as I described?

Joe

ral1960

· #12 · Jul 5, 2009

I switched the underseat fan units between driver and passenger. Now the driver's side works OK, while the passenger's shuts off, so the problem must be in the lower fan unit. The filter looked white on the broken one, but when I pulled it off, one edge was pretty gray. I tried it without the filter, however, and it still shut off. The unit is held together by tiny star screws, so I can't get inside it until I find a tiny star driver.

How does one get to the seat back unit?

jjm01

· #13 · Jul 6, 2009

What did I tell you? Swapping is the way to go. It's very unlikely that multiple units would fail, unless the car was in a flood. Glad it worked out.

How do you get the rear seatback off? VERY CAREFULLY!!! It's roughly a $400 part list:

Get a very thin plastic scraper from a hardware store, file all the edges smooth, and wrap it with duct tape. You will need to insert this homemade tool between the seatback and seat to disengage the two clips on the left and right side of the seatback, so you want to protect the leather. It's also a good idea to use painters tape (and put duct tape on the blue tape for even more protection) on the seat and seatback in the area where you will be inserting the tool for further protection.

When you push the tool down between the seat and seatback (you may have to "feel around" to find the clips), it will disengage the clips, and the seatback will pop off. Once both clips are disengaged, lift the seatback up off the lower "hinge" carefully. NEVER, EVER, force the seatback off because it breaks very easily (metal clips mounted to cheap plastic, and the lower hinge mounting is all plastic), and you won't be able to get it back on.

Replace ALL the filters while your at it... I think it's part of recommended maintenance... they're only around $3 or $4 each or so.

Joe

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ral1960

· #14 · Jul 7, 2009

I believe I'll leave the seat back alone, thank you, if it ain't broke, I'll certainly break it.

I took the fan unit apart today, just to see if it was clogged or dirty, but it was perfectly clean inside and the blade spins easily. There's a small circuit board attached which may be the part that's screwing up. Why it works when it's hot is beyond me. I went by my local dealer to see what a new fan unit would cost, but they were still closed for Independence Day.

Fleetwood96, have you made any progress?

I don't believe I'll ever be able to buy a car without cooled seats--they're well worth the extra firmness of the seats.

ral1960

· #15 · Jul 8, 2009

The fan unit costs $167 at the dealer. Part no. 89045343. The parts guy had to look it up. He'd never heard of it.

fleetwood96

Discussion Starter · #16 · Jul 14, 2009

I have made a bit of progress, but haven't fixed the problem yet. I took the car to the Cad dealership, and they couldn't figure it out either. Without a code being stored in either DOOR module, they had nothing to go on.

So, I started experimenting with the 8 wires which go to each of the fan modules. Since earlier experiments showed that when both fan modules were unplugged, the control module didn't click off, I figured one or more of the 8 wires were causing the problem. My most likely suspect was the RED wire, which makes the fan spin, but what do you know, with only it unhooked from the connector, the control module still turns OFF! I then started unhooking the other 7 wires individually and tracked it down to a pair of LT GREEN wires. If I unplug either LT GREEN wire, I discovered that on the heat setting, the system works perfectly. I get all the heat I can stand and the module doesn't turn itself off! Unfortunately, when I go for the cooled seat button, the fan spins for only a 1/2 second, if that, and then spins down. The control module doesn't click off but there's no action from the fan module. Without a service manual handy, I can only speculate the the LT green wire forms some sort of loop between the controller and the fan modules but are only used during the cooling operation only. I also tried connecting the 2 LT GREEN wires together, bypassing the fan module, and again the control unit just clicks off after 30 seconds of this setup - just like when the fan module is plugged in fully, as though there's some sort of short-circuit within the fan module. So, I'm back to thinking the fan modules themselves are defective.

I found a place selling the 89045343 fan modules for $99 plus shipping. I think my next step is to get a new one and try it out. If anyone needs a brand new $200 control module, just let me know. I couldn't take it back so it's sitting in my kitchen. I might try selling it on eBay to help pay for a fan module.

Doug

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ral1960

· #17 · Jul 14, 2009

fleetwood96 said:
I found a place selling the 89045343 fan modules for $99 plus shipping. I think my next step is to get a new one and try it out. If anyone needs a brand new $200 control module, just let me know. I couldn't take it back so it's sitting in my kitchen. I might try selling it on eBay to help pay for a fan module.

Doug

Do tell where you found it.

I can survive with one working cooler, but if it goes, my backside sweats too much for leather seats.

Did both seats start acting up at the same time?

One odd thing I noticed: With the bad unit unplugged, I no longer hear a loud click through the speakers when flipping the turn signal when the 6 CD unit is running.

They've got most of the mechanical stuff pretty reliable--it's all the electronics that cause the gremlins nowadays.

fleetwood96

Discussion Starter · #18 · Jul 17, 2009

It's www.partsdirect.com

fleetwood96

Discussion Starter · #19 · Jul 17, 2009

Sorry, that's www.gmpartsdirect.com

Sometime during the spring months when I was using neither the heated seats nor the cooled seats something must have happened. Back in the cooler months the seat heaters were both working OK.

ral1960

· #20 · Jul 17, 2009

Thanks. I had no luck on Ebay.

Looks like someone would have totaled a Deville with cooled seats by now. I don't know where or how wrecked cars are parted out these days. I found some parts for my old Eldorado in a junkyard 15 years ago, but things have changed.

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