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Discussion Starter · #1 ·
Has anyone had this issue? I could not see voltage on the leads going to the pad. I measured 622 ohms on the heater pad bottom cushion so I replaced the control module on pass side but have the same problem. Wondering if there is a common problem? Check fuses om M8 and M9 and every other fuse and they are all OK. Any help is much appreciated.
 

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2001 WJ/WG, 3.1TD VM Motori.
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Only thing I could suggest applies to WJ's, but I'm wondering if the same is now starting to happen to the later GC's? I am also at your level of probing the issue, but in my WJ- heated seats not heating.

Usually, the seat element burns out on our seats, but you have resistance on the pad wiring itself, which indicates that circuit is okay just like in my case.
So, with no power going to the pads, the next step would be to test for power going to the switch itself in the control unit from the fuse box, if you see no problems with the fuses or any relays in the rest of the circuit (which I couldn't in my case).
If those lines are working, then I would suspect the switches themselves, even though you've replaced the pass. side already. Do they have led indicates in them like WJ's? All of mine are shot, so I suspect its the switches in mine.
Hopefully, 2012 model yr owners can jump in with their experiences to guide you.

(Cold bums on leather seats in winter isn't fun, nor is putting a blanket on them so you slide when braking!)
 

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Discussion Starter · #3 ·
Only thing I could suggest applies to WJ's, but I'm wondering if the same is now starting to happen to the later GC's? I am also at your level of probing the issue, but in my WJ- heated seats not heating.

Usually, the seat element burns out on our seats, but you have resistance on the pad wiring itself, which indicates that circuit is okay just like in my case.
So, with no power going to the pads, the next step would be to test for power going to the switch itself in the control unit from the fuse box, if you see no problems with the fuses or any relays in the rest of the circuit (which I couldn't in my case).
If those lines are working, then I would suspect the switches themselves, even though you've replaced the pass. side already. Do they have led indicates in them like WJ's? All of mine are shot, so I suspect its the switches in mine.
Hopefully, 2012 model yr owners can jump in with their experiences to guide you.

(Cold bums on leather seats in winter isn't fun, nor is putting a blanket on them so you slide when braking!)
I agree with your whole post (especially the last part). Yes, both switches have LED indicators. One for high and 1 for low. They must have a common feed from a relay in the fuse box. I would love to see a wiring diagram for the feed from the fuse box, to the switches and then to the control module under the seat. Cooling works and I can see voltage on the test lite LED, but when I test the heater voltage wire, I get a small LED pulsing, but not detectable with a volt meter. I'm going to try the service dept at the dealership I bought my newer Jeep GC for the schematic.
Thank you Seakir for replying.
 

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Have you checked relays? You’re pre facelift so won’t have any of the canbus issues associated with the late 2013/all 2014 MY. If both have failed, it’s more likely to be a fuse or relay that seat element burn out unless it’s possible you have just not picked up on one not working until both have failed? If the switches are lighting up & changing the led between high & low mode then it’s unlikely to be the switch. I would be inclined to dig out a multimeter & see if there’s a voltage when switches are activated. As you don’t have can pulses, this should be an easy way to check continuity
 

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Discussion Starter · #5 ·
Have you checked relays? You’re pre facelift so won’t have any of the canbus issues associated with the late 2013/all 2014 MY. If both have failed, it’s more likely to be a fuse or relay that seat element burn out unless it’s possible you have just not picked up on one not working until both have failed? If the switches are lighting up & changing the led between high & low mode then it’s unlikely to be the switch. I would be inclined to dig out a multimeter & see if there’s a voltage when switches are activated. As you don’t have can pulses, this should be an easy way to check continuity
Thanks for your reply. I'm going to dig deeper into this tomorrow. I watched a youtube video of the seat diagnosis with a scan tool. Didn't know it could do that. I'm going to check both front seats to see if I get an identical ohm readings on the element and see if the control modules on each seat have the same indicators. I was so sure I had the right diagnosis, I replaced the seat control module ($200 CDN) but to no avail. I may have to get it diagnosed by a pro. cheers.
 

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Discussion Starter · #6 ·
Thanks for your reply. I'm going to dig deeper into this tomorrow. I watched a youtube video of the seat diagnosis with a scan tool. Didn't know it could do that. I'm going to check both front seats to see if I get an identical ohm readings on the element and see if the control modules on each seat have the same indicators. I was so sure I had the right diagnosis, I replaced the seat control module ($200 CDN) but to no avail. I may have to get it diagnosed by a pro. cheers.
I can hear the relays clicking in the seat control module so that's why I think the problem is back towards the feed to the switches.
 

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If you can hear relays clicking when hitting the switches then surely the switches are doing what they are meant to? They are activating the relay when pressed so narrows it down to post that point in the wiring. It’s gone midnight here but will see if I can find the relevant section in the workshop manual tomorrow. I know I definitely have the info for the later ones plus a whole torn down interior here but will have to check for the earlier ones
 

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Has anyone had this issue? I could not see voltage on the leads going to the pad. I measured 622 ohms on the heater pad bottom cushion so I replaced the control module on pass side but have the same problem. Wondering if there is a common problem? Check fuses om M8 and M9 and every other fuse and they are all OK. Any help is much appreciated.
did you mean 6.22 ohms? . The specs are below.
 

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Discussion Starter · #9 ·
did you mean 6.22 ohms? . The specs are below.
Thank you for the reply and the specs PDF. Yes, I believe I measured the parallel at 6.22 ohms and that's what fooled me on the voltage meter scale. I bit the bullet and had the trouble diagnosed with a thermal imager and scan tool. the problem is an intermittent one with the bottom cushion heat pad, the one that usually is the problem.

I now know where to proceed to fix this issue. I had the seat out and torn apart once so this next time should be OK.
Again, thanks to everyone trying to help me, (a still trying to fix things the old way retired telephone man) cheers :)
 
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