Triumph Sports Cars

Perhaps I should acknowledge at the outset (as if there was ever any doubt) that I am an MG guy, and I realize that there are philosophical differences between the MG and TR camps that perhaps I really don't understand. But having said that I also must admit that I'm really not having an easy time understanding what is going on with the TR-7 wiring, in particular the A/C wiring, fan circuits, and the start circuit. It seems to me that there are rather established ways to do things like energize relays for instance, but when the TR electrical engineers designed the circuits for the TR-7 it seems they got really creative. Don't get me wrong, I usually think creativity is a good thing. But not with electrical circuits. They are difficult enough to follow already. Like the interconnect from the A/C condenser fan relay to the starter solenoid. I get it that not running those fans gives more battery to crank with, but isn't there already a delay circuit for the master relay? (More needless complication by the way) And isn't the white/pink wire from the ignition switched on only in the "run" position? So why does it become necessary to feed the relay ground through the starter solenoid to get the relay to turn off when voltage is applied during cranking? Couldn't they have just sourced it through the white/pink wire? So much simpler and easier to follow ant troubleshoot. Then they do the same thing on the heater fan end of it and have to put diodes in the wires to avoid backfeeding other circuits. And how does it make sense to feed the condenser fans on separate fuses yet turn them on with the same relay? If one doesn't run the air blown by the one that does just recirculates back out the one that doesn't instead of going through the condenser. It just creates twice as many failure points. And then there's the whole thing about running the harness from the fuse panel up to the right corner, around and up over the nose of the car, back down and through a bulkhead only to fit a multipin connector and run it right back through the very same bulkhead then down around the bottom of the nose to get to the fans. What the heck?!! How does that make any sense at all? Yet they did the same thing with the starter interlock wiring at the firewall. It's hard enough to figure out where the wires go without snaking them all over the car with connectors everywhere. You get an open circuit and it could be anywhere.

OK, I guess that's a bit of a rant. Sorry. All I wanted to do was fit an electric radiator fan. But I noticed one of the condenser fans wasn't running, then noticed that the contacts in the fuse panel had gotten so crappy that they would never be reliable again, so I rewired the source directly to the battery with an inline fuse the same as I was doing with the new radiator fan, but then since the fans wanted to run with the engine and A/C off I had to get into that whole mess with the A/C control relays. I installed new relays for the fans over on the battery side so the power circuit is direct and short and now I have to figure out the relay control side. The radiator fan seems simple enough, verify that the white/pink wire is unpowered in "start" and powered in "run", use it to power the relay, and ground it to a thermostatic switch on the intake manifold. On the condenser fans it isn't quite so simple. If the white/pink had been used to supply the relay coils it would be, as the manual cutout and heater blower would all be on that switched circuit. But they are on the white circuit which is powered in "start". Seriously, what is up with that? If you want to cut out the condenser fans and the A/C compressor to get more cranking power don't you also want to cut out the wipers, washer, and heater motor? It just all seems so confused. I guess I'll find a way to make it work, but what should have been a pretty simple job has turned into a week long ordeal. I guess I'm just sharing my misery. I'm already pretty sure there is no help to be had.

Jim

Jim. On the brighter side, Wired weird are anagrams of each other and alliterated also. Sounds like rewiring would be easier.This illustrates why these cars are no longer in existence. This gives me an opportunity to say I've been reading up on the history of your car. Pretty amazing and interesting story. Excellant reading and still lots to go. Cheers Tim

Thanks for the compliments Tim, and I did rewire my car a few years back, but I'm not real keen on jumping in and rewiring Edith's TR-7 just now. It is however forcing me to try and understand it.

For instance, since the white/pink wire does indeed turn off when cranking (confirmed), WHY is it necessary to add a delay circuit to the A/C? That's an added relay and flasher unit, for no cause I can see but to create a 2 second pause when turning on the A/C. Couldn't be for starting the engine, and once the engine is running who cares? I think maybe I'll just remove that circuit, it's that much more to go wrong.

Then here's another weirdness. Right center relay beside the fuse block. Has a big brown wire as a feed, white/brown load, white and red control wire. Start relay? Who knows? It isn't on the schematic!

I'd love to just give up. Unfortunately that is not an option.

Jim

Timothy - ALL of these cars are are no longer in existance. Not just the TR7's. Seems the Lucas smoke leaked out of all of them. :(

Dan,

There are about twenty variations of wiring diagrams for TR7's - and that's just the AC models. The engineers did very weird things by today's standards. Most of the relays and such I feel are are wired backwards, that is, power to the fan and then the relay and ground. Very strange.

Anyhow, I've never seen the interconnect from the A/C condenser fan relay to the starter solenoid. There is a brown wire feed from the battery that has a union that splits off wires to the starter relay and the condensor fans, switching from brown to purple green and purple pink at fused links. Cranking should not impact the condensor fans through this circuit.

As you said, the white/pink powers only when you are cranking the motor, but it feeds the delay relay which cuts out the interior heater fans, the AC compressor clutch (to keep it disengaged), and a few AC other bits and the radio. As far as I know, it to has no impact on power to the condensor fans.

I'm not aware of any diode on the heater fan, only the condensor fans. This prevents back feeding when running in low speed mode. Good old Triumph engineers, wiring single speed fans to run as dual speed (they run in series for low speed and parallel for high speed). Took me ages to figure out what the heck they were doing.

Here is a link to a doc that I found that is pretty clear on how the AC circuit works: [docs.google.com]
And another one on separate wiring: [docs.google.com]
(Mar 4 - fixed the bad link to the first doc and added one to another. M)

Good luck sorting it out!

Martin



Edited 4 time(s). Last edit at 03/04/2012 10:53AM by bsa_m21.

Martin, thanks for the links, that is some good information and I wish I had it earlier. My wiring seems to be different (TR-7 vs TR-8 I'm guessing) as both fans appear to switch on simultaneously using one relay. I see no way they could operate in series but will look again. However the ground side is direct to the relay so I don't think it was possible on this car. (US 1980 TR-7 DHC with A/C and carbs) I think I will set it to always run the condenser fans at full speed when the A/C is on (airflow is not that impressive), run the radiator fan from a manifold mounted (Buick V6) thermostatic switch, and possibly add a manual override. I saw mention of the starter interconnect which is as described, providing a ground for the condenser fan relay. In this car this would not turn off the heater fan etc, just the condenser fans. However the delay circuit will turn off the compressor clutch and the throttle jack (only). I think I'll rewire the sucker, get rid of the interconnect and delay circuit and control all that with the W/K wire, with the new relays placed over on the other side for the fans, leaving only the A/C Master Relay on the left. This should simplify things immensely and give a much more reliable circuit, as well as a lot more room to get at the wiring if needed.

At present I have an issue with the control signal for the Master Relay so it looks like I'll have to go back into the console to sort that out (once again). But because I am getting really tired of this business of doing things over many times I am eliminating unnecessary connectors, functions and devices, using sealed connectors where I can, and doing whatever else I can to upgrade to more modern devices. Where I need wire I am using the cross-linked insulation like what comes in the AAW kits. I figure if I just upgrade the circuits that cause trouble as I go along I can put off rewiring the car long enough that I may never have to do it.

I will check into the '85-'88 Saab 9000 radiator temp switch. If it has a wired pigtail and isn't ungodly expensive that might make a good alternate to the manifold switch, is right beside my relay box, and I wouldn't have to find a place to mount a manifold switch so I might use it. OTOH, if it turns out that even with the fans working properly the radiator is inadequate (a definite possibility), I will be looking at aftermarket generic radiators with oil coolers and will most likely need the manifold mount switch anyway. Because I may have a good usable Ford sealed unit I may just use that as it is likely to be more reliable, even if I have to put a "T" on the intake manifold to accommodate it.

Jim

Looks like the radiator switch slip into a grommet through the radiator tank. The Saab switches are threaded. I'm not real sure how well that will work but I guess it does. But it sounds like maybe I'd better stick with the manifold switch.

Jim

Dan,

So if its a 1980 carb USA, then this must be your wiring diagram:



This is a real dogs breakfast. I would change it over to the 1981 wiring. Much simpler:



Here is a doc that describs how: [docs.google.com]

Full 1980/81 workshop manual is at: [docs.google.com]

And the ROM Suppliment is at: [docs.google.com]



Edited 1 time(s). Last edit at 03/04/2012 04:20PM by bsa_m21.

Yep, I think that's it. Thanks for the link but since I will be keeping the A/C function (spent good money to make it work and it does work quite well until the engine overheats), those instructions are a bit off point. I think I will go with the above plan. I see no reason to keep the delay circuit, I think it just adds complexity. I have the fan relays on the power side in conventional form, and will eliminate the interconnect. Run Only power (W/K) will take care of the rest and the fans will not run with the key off, which I prefer. All that remains is to determine the control side circuits for the two fan relays and whether to wire them on the ground or hot side. I prefer hot side controls but since the heater fan is a ground side control, to be consistent I should probably go that way with both of them.

So, use the existing heater fan and manual A/C switch to turn on the A/C system and also the condenser fans.
Use a manifold mounted temp switch to turn on the radiator fan.
Power the fan relays off the W/K wire.

The Master Relay will still be energized in Start but since it is powered by W/K it will do nothing until Run.
So no fans , clutch, or throttle jack anytime except Run. Just as God intended. (OK, maybe that was in poor taste.)

Jim

I did find one of those grommet mounted Volvo switches in the Everco catalog:
#36533, '86- '94, 197 on, 188 off, tab connectors.

But I'm thinking about a thread-in dual switch like #36480, 197/221 on, 188/212 off with wire lead outs. I could actuate the radiator fan with the low side and the condenser fans with the high side for extra airflow when not using the A/C. If I can get it that is. Turns out to be a Saab part, around $50. Pricey, but no pigtail needed as I have junkyard Ford connectors I can use.

Jim

Jim,

If you need to look at a manual, there are two in the trunk of my car. One of them has a wiring diagram I printed off in it I think.

Thanks Dan. I've got one too so no problem there. It's just the strange way they routed the electrons that makes it difficult. But I think I have it figured out now.

Advance crossed the Everco temp switch to an IMC 80237005615, for $23.31 tomorrow pickup. So good there. It is a threaded radiator mount though rather than pipe thread so it will need an adapter, but since I'll probably need a "T" to install it anyway I may be able to just modify one leg to match, depending on the thread size.

So, sort out the console switches and it should work fine, and hopefully be reliable. Then it's just a question of radiator capacity. I'm not real hopeful on that but we'll see.

Jim

OK here's a twist, and this one nearly had me flummoxed. On the heater blower speed control switch the wires don't come anywhere close to matching the 1980 schematic or anything close, but looking back to '77 I see matching wires on the speed switch: green/pink, green yellow, green/slate, black (one wire, not two) but no connection for purple/green which is the control line to the master relay. Where is it? And I spy a purple/green wire up around the blower motor, right size and in about the right area, sort of. Where does it connect? Dunno. It's one of those stand-on-your-head impossible to get at things. Apparently connects to the Gn/Y wire, but why at the blower?? Guess I'll jumper the Gn/Y at the switch to the Bk/O at the manual switch as there seems to be a disconnect somewhere up around the blower. Throttle cutout and cold thermostat left with the old engine so no need for all that round-about wiring any more.

Jim

Since the delay circuit works I decided to just leave it in. It may serve a useful purpose if the high pressure switch drops out, and if it becomes unreliable it will be easy enough to bypass later. I tapped into the master relay power (white/pink- switched:Run) to power the fan relay coils, and used the existing radiator thermostat wire (Slate/Red) to send the A/C run signal back across to the condenser relay. Looks like I should put one of the diodes in this wire as otherwise an overheat condition (221 degrees or more) will bypass the A/C master relay and light off the compressor. Not exactly what you want with a hot engine. I don't like the connectors on it but if I enclose it all in heat shrink maybe that'll keep the O2 out. Looks like the worst of it is past now so I hope to finish up soon.

Jim

Jim,

Don't use the 1976/77 wiring diagram. Completely different wiring.

In your 1980 wiring diagram, look at symbols #14 & #15, the cold thermostat and the fan switch. Although it doesn't label it (ah the Brits), there is an in-harness connector between them, with the purple/green splitting into three wires, green/pink, green yellow, green/slate, with resistors dropping the power to green yellow & green/slate. At the switch, it should look like this:



On the left side of the heater matrix (sorry, no picture), the purple/green wire goes to the cold thermostat (#14) then back into the engine compartment for the throttle cut-out (#13), where it changes to black/orange, then back to the heater matrix to the manual cut out switch (#12) on the lower console, then becomes purple/brown and connects to the master relay (#40).

Clear as mud, eh? Having fun yet?

M.



Edited 1 time(s). Last edit at 03/05/2012 09:29PM by bsa_m21.

Thanks Martin. Apparently the cold thermostat is open because of.... well the cold naturally enough. Who would have ever figured that one out? And here I was thinking maybe it was something on the (ex)engine. Well, I guess I won't be needing that one any more since I rewired the sucker. Seriously though, did they really think the car would get so cold that you need an automatic switch to turn off the compressor? In a convertible? When they already have a thermostatically controlled expansion valve?

I have to admit, they were thinking ahead on this heat/AC system though. Thermostatically controlled heat, thermostatically controlled cold, multiple safety overrides. A few more devices to turn the system off and it would have never run at all. If they had just stuck to the basics reliability would have gone up a lot. Waited for the modern electronic controls which also had teething issues. No way to win except by sticking to what worked reliably, and even that was not a reliable tactic as proven by other marques. I guess SOMEONE had to try going high tech. (Oh yeah, by all means let's do THAT with Lucas components!)

I tied into the Gn/Y wire to the blower resistor right behind the switch and went directly to the manual cutoff switch with a wire about 1 foot long. Short, sweet, and to the point. I THINK if it gets too cold I can roll down a window or something. Actually more importantly, if I want to run the AC in cold weather to defrost the windshield I don't want some danged old automatic cold thermostat telling me it's too cold to work (brrr...).

Some time back I had replaced the heater's leaky thermostatic valve with a manual one but that was one automatic feature it would have been nice to retain. Too late I discovered a Volvo replacement that was still available but I'm not pulling the matrix back out to install one. Manual heat control works just fine.

Once you begin to understand how this all works it really isn't so bad... except for the lousy connectors... and the bad components.... and the weird wiring... and the torturous locations.... and the upside down control schemes... and all the rest that I've left out... what's left is really quite,.. er,.. below average I'd say. Well, no, for it's day, maybe sub-par. But not much. I mean, about all that leaves is the wires themselves and they are the plain old (OLD!) vinyl coated wires of previous decades, prone to drying out, cracking, and corroding just like their ancestors. It's really quite remarkable how much smoke is still left in the old creatures.

Now, looking forwards, in general our electrical systems are sealed up quite nicely against the incursion of water and oxygen with their ruinous effects except for two things. Relays and fuses. Even with o-ring sealed covers the fuse and relay blocks are open at the bottom and are therefore vulnerable. Fitting some sort of a sealed lower cover would make them much more reliable in the long run. But the cross-linked insulation on the new wires is really remarkable, as are the sealed connectors. Most aftermarket switches and components are vulnerable too but some very good ones exist. Many OEM ones are exquisitely designed. Clearly the enemy has been identified and the battle rages in earnest.

Onward,

Jim

Hmmm.... High tech? Lucas? In the same paragraph? Oh my... :)

"... the lousy connectors... and the bad components.... and the weird wiring... and the torturous locations.... and the upside down control schemes... and all the rest ..." Yup. They sure are quaint. You either love'em or hate'em. That's the company good old George founded.

Amazing thing was that they also did aircraft electronics, and had an excellent reputation for, dare I say it, reliability.

I'm just glad that by some fluke my TR7v8, after 32yrs, still has some of that famous Lucas smoke left in the system. Better get the damn car out on the road before the rest leaks out....

M.

No kidding. Naturally complications have arisen. The "cheap" (yeah, right) Saab switch turned out to be neither cheap nor available, plus would need an adapter so I'm taking another look. Thought the one we put on the Roadmaster looked promising... 3/8" pipe thread, nice sealed connector if I can find a pigtail for it, 3 pins... Carl found the P/N for me: TU178TG and Bill picked it up at the local AZ. So.... A search brings up... NOTHING! NADA. ZIP. Now that is a rare occurrence these days on the internet. Google, Dogpile, even the AZ website, nothing. Nothing at 4 seasons either or at Wells. Guess I'll stop by the store and see if they have the part there just for the sake of continuity, otherwise I might have to think that it was one of those inverse black hole functions. It certainly was not the switch Bill thought he was buying. IF they have it, and IF I can find a pigtail, and IF the switching points are acceptable (sounds like some stove top testing may be in my future) I may use it here. I'm guessing the application may be a car (GM V6 Camaro?) too new to be in the system. At least the price is right. 15 bucks. Can't beat that for a dual switch.... if it IS a switch.

Then since I have the console out I might as well finish hooking up the seat heat (since it's almost summer already). And since I'm doing that I might as well replace that bad panel in the driver's seat upholstery, and if I'm doing that I might as well see what it would take to put new door panels on it, and if I'm doing that, I might as well glue the carpet back down... It just sort of snowballs, you know? At least there seem to be no other major issues with the wiring.

Jim

Grrrr.... ever feel like you're going in circles? OK, so I bought the TU178TG purely so I could test it, then bought a pigtail to fit it and felt lucky to find that, figuring that at the very least I would confirm whether or not the one we installed in the MG-Roadmaster could be used. Well it can't. Turns out the AZ counter guy was clueless and sold Bill a sensor when he asked for a switch. (he's also headstrong and doesn't listen too easily) It's a sensor. A double sensor in fact, one to drive the gauge and the other to drive the ECM, both at 2K-200 ohms. It's hanging with the electrical parts now and maybe some day it'll get used but I'm not counting on it. Basically $33 down the drain.

So back to the Everco IPB and ultimately back to the Saab switch. Looked like about $55 but ultimately I found a dual Beck Arnley switch on ebay to fit a '93 Saab 9000 for $32.50 with free shipping and ordered it. BA does not list their switch points so it's a bit of a gamble but since the application is the same as the more expensive brand which does, it should be close. Of course I could have just avoided all this and just ordered the $55 switch in the first place, but then the sender (I mean sensor) on the Roadmaster would still be an unknown.

It's a screw-in radiator mount with a sealing washer though, so once I have it I will still need to make an adapter but luckily I have the equipment and know how to pull that off. In the mean time the TR has my lift tied up so I'll just have to find other work to do. That is never a problem around here.

Jim

Jim,

I'm confused. The stock switch p/n BHM7285, cross references to MGB's and XJS's and is readily available. MGB Radiator 1977-80. thermostatic fan p/n URP1126. It can be had for $18 at: [www.mgbsource.com]
Why would you want to switch over to a '93 Saab 9000 for $32.50 and have to make an adaptor??

Stock:


Saab:


I've been told, but haven't tested myself, that a 2004 Audi A6 dual temp fan switch is a direct push in replacement. Tridon p/n TFS219

$15 at Rock Auto p/n VE709097

Hope this helps.
M.



Edited 1 time(s). Last edit at 03/07/2012 11:03PM by bsa_m21.

Good to know Martin. In this case I am anticipating a radiator upgrade and would prefer to be able to use a less expensive generic aluminum radiator. The TR-7 boys tell me the stock radiator can't be expected to handle the Buick V6 and that I'm lucky to have made it this far with it. Considering that Palestine is likely to be hot, and I'll be wanting to run at speed on that trip as well as run the A/C I see that as a formula for disaster in spite of the new electric radiator fan. I agree with them actually, as it would overheat if driven above about 65 mph last summer. Putting the Saab switch on the intake means I'll only have to deal with the transmission oil cooler as an extra feature of the radiator and those are fairly common. Through-the-tank thermostatic switches, not so much.

I suppose I could weld in a bung for the screw in switch but I'd rather not. Mounting the slip in style using spring clips just doesn't strike me as a good tactic. I could probably do it but I'd rather not.

Those references are excellent resources and thanks for posting them.

Jim