Radio Supply Connector

[Tri 250]

I acquired a 73 TR6 in August 2020 and am just beginning to sort through some of the electrical issues. The heater fan was first on my list. Got a fried wire leading back to the motor. Not good. I traced the wire back to the heater switch. I found another fried wire leading from the heater switch back to the harness. The wiring diagram shows that a green wire is "supposed" to feed power to the switch, however, the wire that is feeding power appears to be white. After studying the wiring diagram and tracing the fried white wire back to the ignition switch, I was able to determine this was the pink / white wire for the radio supply. Now my question......is this the way the factory wired the car? The wiring diagram says "no", but I can't find a green wire anywhere that seems out of place.

I read a post from HunterTR6 from April 2019 with a similar issue. He too has a 73 TR6. I was wondering if this is the way the cars were wired. Based on what I've read in the earlier post, it's best to find a way to tap into one of the green wires that are labeled on the wiring diagram because they are fused.
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Looks like I will be pulling the heater at some point. For now, I'll be insulating the tabs that are not being used on the back of the heater switch to prevent future '"sizzling"

[RatRidgeRoadster]

Very interesting. I was unaware the White/Pink radio wire was terminated like that with the bullet connector daisy-chained off of a spade terminal. The molded spade terminal is evidence this is factory wiring, but I find it baffling that they would use an unfused wire feeding the fan circuit.

I would certainly be interested if anyone else has seen such a configuration on a 73 or later car, either connected to the heater switch or connected directly to a radio or possibly just hanging loose if no radio.

You mentioned another fried wire leading back to the motor; was it the green/yellow or green/brown? They look good in your picture.

An easy place to tap into a green wire is where the wires drop down into the gearbox cover.

[Tri 250]

Hi Jim

Thanks for your response. The wire leading back to the fan motor is the green/yellow wire (attached pics). It's hard to see from the pics I posted of the switch itself. I tested the "bare wire" leading back to the heater and it has power when switched. I'm afraid the fan motor could be fried. I'm going to have to pull the heater regardless to see what is going on and might as well inspect, test, and clean the core while I'm in there. The floor pan on the passenger side has evidence of a leak at some point due to the scaley rust I found when I yanked out the carpet that PO had glued down. The right corner of the original cardboard transmission cover must have deteriorated. I'm thinking it may have been soaked with antifreeze as this was covered with Bondo when I pulled the carpet out. Also, thank you for the lead on where I can tap into a green wire. It's certainly one of the easier wires to access.

I thought the same thing when I saw the connector for the radio lead (white / pink) on the back of the heater switch. It's why I'm a bit puzzled and am questioning if this was a factory wiring install. It is odd that this was not fused, but the wiring diagram for the 73 does not show this wire as fused either?????

Hope to get some chatter from some 73 owners on what they might have.

Gary

[lfmTR4]

Can’t tell you about the pink white wire but I can confirm that the heater fan switch has some hot external tabs that if they come in contact with the metal dash will generate lots of smoke. It’s not had to do, all that has to happen is for it the get loose. Best to make all your connections then put a couple of wraps of electrical tape around the outside the switch and tabs. I always thought radios were dealer adds so I would imagine the wiring would be too.

[poolboy]

I installed a radio in my 73, but the PO had installed the harness. I found the radio connection wire on the ignition switch in so to speak an 'accessory' position
Tell me this, on your car if the radio wire came off the heater fan wire, was there an "accessory" key position where both the fan motor and the radio could be powered prior to the IGN/ON position....OR did the ignition key need to be fully turned to IGN/ON for the radio to work ?

[Tri 250]

As best I can tell, there is only one turn of the ignition switch to "IGN/ON" before providing power to the starter (i.e. no accessory position before IGN/ON). Therefore, this would provide power to the radio and heater fan at the same time using the white/pink wire as power. After reviewing the Bentley workshop manual, they picture (see attached) an accessory position on the ignition switch. Is the accessory position accessed to the left as the key is inserted? I haven't tried this yet. I've only turned key to the right.

[Tri 250]

Later switch diagram - posted earlier switch in error. Is position 1 accessed with key turned to left?

[poolboy]

On my ignition switch the Radio get power at one clockwise click before the IGN/ON position.

[Tri 250]

OK. My switch may be worn which might be the reason I'm not getting the click for the accessory position. I'll check this afternoon and put a tester on the wire to determine if I get any power to the white/pink wire before the ignition position is selected.

Do you have a green wire feeding power to your heater switch or is it connected like mine from the radio accessory wire?

[poolboy]

The power for the radio comes from the ignition switch in the accessory position and of course also when ignition switch is in the ON/RUN position
The fan does not come on in the accessory position, only when the ignition key is in the ON/RUN position

[RatRidgeRoadster]

With the green/yellow wire melted, it does seem you had a short to ground somewhere inside the heater case or motor, or possibly the armature is/was frozen. You said you"tested the "bare wire" leading back to the heater and it has power when switched". Is the motor operating or making a hum? Could be the rotor or stator winding has burned out if neither, but regardless of the answer, you will need to pull the heater.

[RatRidgeRoadster]

I always thought radios were dealer adds so I would imagine the wiring would be too.

Lou, the AAW diagrams show the white/pink radio wire on 73 and later cars. Starting in 74 they even added speakers and the antenna on the left wing to all cars, whilst the radio was still optional.

[Tri 250]

Jim

Interesting comment about the radio accessories in 74. Cool stuff! I learned something new. I guess this explains why I have seen antenna mounted to the left front wing. So, prior to 74, the cars that have console trim panels did not have the speakers there? My 73 has the console trim panels w/o speakers, but has a speaker mounted under the firewall on the passenger side like most of the early cars.

Gary

[Tri 250]

This afternoon, I tested the white/pink wire that was connected to the back of the heater fan switch. After looking closely at the ignition switch, I did confirm that I have the accessory position and got it to click after turning slowly. I did get power in this position and in the ignition ON position. Therefore, the fan would have been able to run in the accessory position in addition to the ignition ON position.

I was reading some comments about heater switches on TTE and found another '73 owner describing the white wire that lead to the back of his heater fan switch. He had the same issue......his melted back to the ignition switch.

Besides my car, I've read that a couple of other '73 owners have the white/pink wire providing power to the heater fan switch instead of the green wire that is showing in the wiring diagram. I don't have positive confirmation, but I'm beginning to think that Triumph ran the white/pink wire to the back of the heater fan switch for power and then had the small pigtail with bullet connector come off this connection. like mine, for the radio power feed. What doesn't make any sense is that the white/pink wire is not fused and therefore sets you up for a melted wire like several of us have described. I have looked all over the back side of the dash and cannot locate a loose green wire. I have accounted for every wire behind the center gauge cluster and the wires that lead back into that section of the harness. I also could not find any evidence of a wire that had been clipped.

[poolboy]

If it makes sense to you,I'd splice the heater into a white wire from the ignition switch using an inline fuse whatever size somebody who knows tell you.
And if the radio isn't fused, fuse it but leave it powered at the Accessory position

[Tri 250]

Good idea, Ken, and I was thinking the exact same thing. The other option I was thinking about was to run a green wire from the voltage stabilizer over to the switch. Either way would be a fix. I’m kind of leaning towards the fused white wire option.