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Discussion Starter · #1 ·
So I am trying to sort out a wiring mishap on Exmoor heated seats. The installer moved wires and did not use the system as designed. As I am knee deep in wiring behind the dash, I want to redo the wiring so that the wire colors match up. Heated seats are Exmoor.

I am trying to figure out which terminal goes to Ground, Switched power (15amp), Unswitched power (30 Amp) and which terminals go to the seats (high and low).

I am also trying to understand how the high and low heat settings work. Does the high setting cause current to go through both output circuits?
(terminal numbers are 30, 85, 86, 87, 87a)

Thank you for the help.
 

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87a and 87 is an either or relay, so you only have 1 output to the 30 terminal.
The diagram is terrible because none of the terminals are marked, just lines representing current flow, ie wire routing.
If you label the terminals, then it will be possible to discover what is happening (connected where).
 

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From that diagram the relay is supplying power to the heater switch with the ignition on. The control of off, low and high is within the unit.
 

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Discussion Starter · #4 ·
Yeah, It all does not make sense to me. I thought that one of the purposes of relays are to keeping the higher amp current from going through the switches. The information from Ex-Moor is beyond terrible. I agree the diagram is crapola but I am trying to sort it out to figure out how to make it work.
Ok, I think I have it figured out. I was confused as I thought the purpose of the relay is to avoid higher amps going through switch but it appears that circuit goes through the double pole switch and the switch determines which circuit (higher or lower resistance) goes to the seats. I will know more tomorrow when i play with the relay/switches on the bench. Thank you.
 

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That diagram is a bad design. You do not want the load onto the switched circuit in a Defender. The relay is taking the low current off of the switch only, which makes no sense at all.

If you don't want the load on the switch, you need two relays. The power going through the relay(s) 30 to 87 should come form a fused continuous source, not a switched source.

Battery -> Fuse -> Relay terminal 30 / Relay terminal 87 -> Seat heater (one relay each for low and for high). Other side of heaters to ground. All wiring to be sized for less than 5% voltage loss at rated amperage.

Power from any switched and fused circuit -> Heater switch -> Relay terminals 85 / Relay terminals 86 -> Ground
 
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That would be right if you want the relays to unload the switches.
 

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I have no skin in this game, and what is Red stated above is definitely the best bet. But I think it's overkill. I do not have Exmoor heaters, but the genuine kit as an example is only 3A per seat (as per the wiring kit that doesn't have relays). I would think a pair of relays for both high and low would suffice, and really you could run Carling switches without a relay (wouldn't recommend) if you really wanted to. Most Cig lighters are good for at least 5A, and most don't have relays. Again, just thought for the discussion, relays really make the most sense.
 

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Discussion Starter · #10 ·
Thank you. At least now I have an understanding of the issue. I am running Carling switches. I am a little torn as my tendency toward anal compulsion leads me to definitely following Red90's advice.... But I am also having some project fatigue and want to get the project out of the garage and on the road so there is the easier route allure. I will let you all know what I decide when completed. I mean it is a total dash redo with Carling switches, new VDO speedometer, USB and USB-C ports, Alpine head unit with Rearview Camera etc. It has been fun but back on the road would be "funner"
 

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I run the seat heater circuit a little differently. I have an aux power relay that kicks on with keyed power. It draws directly from the battery and feeds a sub panel with fuses for the seat heaters, heated glass, and a couple other odds and ends. This mess is located under the driver's seat. I use a heavy duty 100 amp relay (autosparks.co.uk) for the panel. The panel has micro AT fuses that light up when blown. These sub circuits get regular old switches since they are not even part of the main harness. My seat heater switches are on the front of the Tuffy console.
So, one relay to power the sub panel and the rest is just running the wires and switches off the fuse box.
 
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Here's what I think is happening:
Assumption, 87a is closed.

So with this wiring, the relay does the switching for high & low, but the switch has the load.
It's silly, but it will work.
Click to enlarge.

.

The seat switch does 1 of 3 things:
1. No output
2. Output (+) to yellow for high
3. Output (+) to Yellow and white for low

When high is selected:
87a supplies (-) current to plug seat B via 30 terminal
Both seat A and B have negative and positive power which makes them heat

When low is selected:
86 has (+) current that interrupts 87a allowing 87 to provide (+) to seat B via 30 terminal which makes it inactive because both sides of seat B are (+).
Only seat A has negative and positive power which makes it heat half as much as high.
 

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Discussion Starter · #13 ·
Thank you so much RdavisinVA and everyone else. I got them working using the diagram in the post above. Now I have to start to new thread to answer a Carling Rocker switch question for a DPDT VJD2 switch. And so it goes....
 

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I'm in the process of rebuilding my 110 including all the electronics and wiring to rid myself of the various PO's horrid attempts. With that said, I have a good understanding of how the high/low versions work now. Here is the basic wiring diagram from generic to understand how it converts the pads from 6V to 12V which is actually kind of cool. No clue if this is applicable to Exmoor.
 

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If you guys don’t mind a possibly dumb question/inquiry from someone who is not electrically minded:

Vehicle is a 2003 130, (i’m in Canada)
I have the Exmoor Kit EXT010-2 sitting in the box.
Should I not install it as it is supplied by Exmoor and connnecting the power leads to a switch lead (like the cig lighter)?
Or should i be adding relays, etc as per some of the comments above.
And should i not be tapping into the cig lighter and instead be looking for another switched power source?

Ask me about MTB’s or Gravel Bikes, Nordic Skis, Backcountry Skis or even GT3’s but the electrical stuff is a bit over my head.

Thanks in advance!

Tracy
 

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I kind of feel like a old school resistive gauge /headlamp dimmer switch would work better than any of these multiple relays. So much simpler.
 

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If you guys don’t mind a possibly dumb question/inquiry from someone who is not electrically minded:

Vehicle is a 2003 130, (i’m in Canada)
I have the Exmoor Kit EXT010-2 sitting in the box.
Should I not install it as it is supplied by Exmoor and connnecting the power leads to a switch lead (like the cig lighter)?
Or should i be adding relays, etc as per some of the comments above.
And should i not be tapping into the cig lighter and instead be looking for another switched power source?

Ask me about MTB’s or Gravel Bikes, Nordic Skis, Backcountry Skis or even GT3’s but the electrical stuff is a bit over my head.

Thanks in advance!

Tracy
You can follow the exmoor diagram which is one relay. Main power needs to come through that relay via a suitably sized and fused circuit.
 

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I kind of feel like a old school resistive gauge /headlamp dimmer switch would work better than any of these multiple relays. So much simpler.
A PWM would work fine. They are cheap. A potentiometer would be tough as it would be large and require cooling. This is a lot more power than dimming some dash lights.
 

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You can follow the exmoor diagram which is one relay. Main power needs to come through that relay via a suitably sized and fused circuit.

So……. is the cig lighter circut suitably sized and fused? I’m sure it’s fused on the factory fuse block (I think). And the Exmoor supplied harness has a 7.5 fuse, one for each seat.

Thanks!

Tracy
 

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I would run a dedicated circuit with proper sized wiring. You don’t want to be sharing load with something else as it will get overloaded one day. There may be an unused circuit you can use from the stock panel.
 
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