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TR2/3/3A Tr3 heater wirer

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sp53

Yoda
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Hi all the wiring harness I bought (BW) does not have a hot lead for the heater on my 1961 tr3. I am thinking that this probably a sub-harness. The schematic says to hook the green wirer from the heater switch to the fuse box. However, that would look kinda unprofessional having a loose wire out of the harness. At any rate, does anybody know if on the original they perhaps borrowed power from say the gas gauge or something?
Steve
 
Maybe because the 3 didn't always have a heater the harness didn't come with one. It says to hook to A2. You can come off a green with a 2 to 1 connection . I would be concerned about draw on it though.
 
I'd have to look at my Herald to see exactly how it's done on the car (don't have a TR3 to look at any more), but what you describe (power lead from fuse box) is pretty much what the Mk2 Spitfire wiring diagram shows. It might have to do with the fact that heaters were optional and, back then, auto manufacturers didn't always build "accessory" wiring into the harnesses. On the Herald, power was taken from the fuel gauge, likely because Heralds in most markets did not have fuse boxes!
 
It's my belief that on the later TR3 and early 3A, the factory took power for the heater from the 'hot' terminal on the fuel gauge. I don't know if that would apply to post-60K cars or not, though.

The workshop manual actually says to connect it to the wiper switch, but of course that only works on earlier cars with the non-self-parking wipers.

I used to have a photo of a relatively unmolested panel, showing the wire for the heater, but I can't seem to find it now.
 
sp53 said:
Hi all the wiring harness I bought (BW) does not have a hot lead for the heater on my 1961 tr3. I am thinking that this probably a sub-harness. The schematic says to hook the green wirer from the heater switch to the fuse box. However, that would look kinda unprofessional having a loose wire out of the harness. At any rate, does anybody know if on the original they perhaps borrowed power from say the gas gauge or something?
Steve
Click to expand...

Yes, simply because the heater in sidescreen cars was always an option. Wire loom suppliers can include a circuit for the heater if you want this extra.

If you were to add a heater later, and ordered the kit from S-T, a switch, wire loom and misc. parts would have been included along with the "wet parts". You can find a complete diagram and instructions in the TR2,3 shop maintenance manual.
htr.jpg
htrwiring.jpg
htrsw.jpg
 
Just curious, Frank, where did you actually get that wiring diagram? I know the factory workshop manual was not in color!

Plus "A2" is the wrong terminal even if the wire did run to the fuse block, as "A2" is hot all the time!
 

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Ah, so it is. The preliminary version that Dan shared with me says only "Where does this wire go?" :laugh:

If you want to run the wire to the fuse block, use terminal A4 (which is fused and controlled by the ignition switch). But I still think the factory used the fuel gauge terminal (which is wired through the harness to A4 on the fuse block).
 
TR3driver said:
Ah, so it is. The preliminary version that Dan shared with me says only "Where does this wire go?" :laugh:

If you want to run the wire to the fuse block, use terminal A4 (which is fused and controlled by the ignition switch). But I still think the factory used the fuel gauge terminal (which is wired through the harness to A4 on the fuse block).
Click to expand...

Randall. you're correct, it would have been A4, and I found the original harness with connection for power at the wiper green terminal.
Regards
 
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