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After a few issues with my drivers seat I thought I'd do a bit of a how-to on how to diagnose and enact a repair.
Problem/Fault
Firstly, this issue normally manifests itself as a failure of one of the seat heaters, the cooled mode generally works.
When turning on the heated seat, it will generally run the fan for a second or two, and then shut down. Please note that it will prevent both seats from operating, even if one of them is actually ok. Once the ignition has been cycled it will then be available to try again, but will do the same again.
Description of system.
The system is controlled by a module underneath the drivers seat (RH seat).
In each seat there are two units, one for the seat base, and one for the seat back. These both incorporate a multi-speed fan (with filter) and a Peltier heating/cooling unit and plastic duct.
The fan blows air across the Peltier which has two sides, both with their own exhaust. One side is blown into the seat and the other is an exhaust for the Peltier.
Depending on the direction of the current, one side cools and the other side heats. This gives active heating and cooling. I believe the later systems had heat pads with a circulating fan. Cooling was passive/ventilated.
The under seat/cushion units are handed, but the seat back units are identical.
Diagnosing
It seems that the vast majority of failures seem to be on the seat back unit. The Jaguar seats don't seem to suffer too much, but there are failures (including my own).
Range Rover and probably other JLR products use the exact same setup and it seems more common on Range Rovers.
Luckily with the seat back units being identical, it should be a case of swapping out the offending side with the known working side. Obviously the drivers side will by far get the most use.
If you've already got the units out and want to test them with a multi-meter then have a gander at this thread for more in depth info.
www.jaginfo.org
Basically though, the two middle wires are for the thermistor and the blue and yellow on the outer side are for the peltier itself. If you've a very high resistance across the peltier then it's likely failed. Low to virtually no resistance and it's probably ok.
I've not heard of any thermistor failures, but mine generally read between 1-1.4K Ohm at room temperature. Dropping down when heated with a hairdryer.
Removals
Firstly, if you've not done this before, it's not difficult to gain access to the seat back unit, but can be a bit fiddly.
The only two tools you'll need is a T20 torx driver. I used one on a ratchet as it saves you taking off the whole seat back, and a flat headed screwdriver.
The flat headed screwdriver is to make separating the connector easier but not really required if you've got some decent nails.
Move the seat forward and tip forward and release any lumbar support.
Sitting in the back of the car, firmly push the plastic seat back cover down. This should allow you to gain access to the inside of the seat back.
If you want to go further, then you can take off the outer side panel and remove the whole seat back, but it's not really needed.
The peltier is in the middle of the seat towards the right hand side and is held in by 3 torx screws. The top two are easy to locate/see but the bottom one is a bit hidden.
Given that I left the seat back, it was much easier to use a T20 torx bit on a 1/4" ratchet.
Lift the whole unit up (you may need to push it forwards into the seat to get the screw supports past).
I found the best way to do it was to lift the whole unit right up first and then pull the fan unit out and down. The middle bar is what makes this difficult.
Repairs.
The first step is simply to swap it with the opposing side and check its function, as I said its very likely to be the drivers side seat back that's failed as that's the most used.
Put the passenger side into the drivers seat and test. If it's confirmed that it's the drivers side unit that failed then you'll need a replacement peltier unit.
I've managed to source a new peltier unit from here.
Problem/Fault
Firstly, this issue normally manifests itself as a failure of one of the seat heaters, the cooled mode generally works.
When turning on the heated seat, it will generally run the fan for a second or two, and then shut down. Please note that it will prevent both seats from operating, even if one of them is actually ok. Once the ignition has been cycled it will then be available to try again, but will do the same again.
Description of system.
The system is controlled by a module underneath the drivers seat (RH seat).
In each seat there are two units, one for the seat base, and one for the seat back. These both incorporate a multi-speed fan (with filter) and a Peltier heating/cooling unit and plastic duct.
The fan blows air across the Peltier which has two sides, both with their own exhaust. One side is blown into the seat and the other is an exhaust for the Peltier.
Depending on the direction of the current, one side cools and the other side heats. This gives active heating and cooling. I believe the later systems had heat pads with a circulating fan. Cooling was passive/ventilated.
The under seat/cushion units are handed, but the seat back units are identical.
Diagnosing
It seems that the vast majority of failures seem to be on the seat back unit. The Jaguar seats don't seem to suffer too much, but there are failures (including my own).
Range Rover and probably other JLR products use the exact same setup and it seems more common on Range Rovers.
Luckily with the seat back units being identical, it should be a case of swapping out the offending side with the known working side. Obviously the drivers side will by far get the most use.
If you've already got the units out and want to test them with a multi-meter then have a gander at this thread for more in depth info.
Heated and cooled seat ecu location
Going to replace the heated and cooled seat ecu on my drivers seat as it's failed,have a brand new one and asked the dealer where it's located and they provided a diagram which shows it mounted under the seat at the very front,however I don't think it's correct.Think it may be located on the...
www.jaginfo.org
Basically though, the two middle wires are for the thermistor and the blue and yellow on the outer side are for the peltier itself. If you've a very high resistance across the peltier then it's likely failed. Low to virtually no resistance and it's probably ok.
I've not heard of any thermistor failures, but mine generally read between 1-1.4K Ohm at room temperature. Dropping down when heated with a hairdryer.
Removals
Firstly, if you've not done this before, it's not difficult to gain access to the seat back unit, but can be a bit fiddly.
The only two tools you'll need is a T20 torx driver. I used one on a ratchet as it saves you taking off the whole seat back, and a flat headed screwdriver.
The flat headed screwdriver is to make separating the connector easier but not really required if you've got some decent nails.
Move the seat forward and tip forward and release any lumbar support.
Sitting in the back of the car, firmly push the plastic seat back cover down. This should allow you to gain access to the inside of the seat back.
If you want to go further, then you can take off the outer side panel and remove the whole seat back, but it's not really needed.
The peltier is in the middle of the seat towards the right hand side and is held in by 3 torx screws. The top two are easy to locate/see but the bottom one is a bit hidden.
Given that I left the seat back, it was much easier to use a T20 torx bit on a 1/4" ratchet.
Lift the whole unit up (you may need to push it forwards into the seat to get the screw supports past).
I found the best way to do it was to lift the whole unit right up first and then pull the fan unit out and down. The middle bar is what makes this difficult.
Repairs.
The first step is simply to swap it with the opposing side and check its function, as I said its very likely to be the drivers side seat back that's failed as that's the most used.
Put the passenger side into the drivers seat and test. If it's confirmed that it's the drivers side unit that failed then you'll need a replacement peltier unit.
I've managed to source a new peltier unit from here.
Peltier element for seat heating Range Rover L322 HHK500060 LR034450 repair | eBay
FITS ALL RANGE ROVER L322 MODELS FROM 2002 WITH HEATED/COOLED SEATS. Fault code(s): B1231-7A and B122F-98.
www.ebay.co.uk
