TR4/4A Stumped on Electrical Wiring--TR4A

[KVH]

I've got two problems. My turn signals work fine, but the green dash light doesn't blink, and my dash gauges have to lights when the headlights are on.

All else works.

From the lighting switch there are several wires, one of which is brown. It just hangs loose. My wiring diagram shows that to connect to a green and brown wire.

However, there is no such wire available to connect under the dash--that I can find. The only one which "might" have been available is already used for the turn signal switch.

Any ideas?

 

[TR3driver]

My turn signals work fine, but the green dash light doesn't blink,

Assuming you've checked the obvious things (bulb is good, making contact in the socket, ground wire is present, etc.) then I would suspect the flasher itself. There seem to be several flashers being sold as correct for our cars that don't actually work correctly.
<div class="ubbcode-block"><div class="ubbcode-header">Quote:] and my dash gauges have to lights when the headlights are on.[/QUOTE]Does the rheostat do anything? If you can find a spot where they work, even briefly, then likely the rheostat itself is bad. It may be bad because of a short, so I would probably start by bypassing it temporarily and see if the tail light fuse pops.
<div class="ubbcode-block"><div class="ubbcode-header">Quote:]From the lighting switch there are several wires, one of which is brown. It just hangs loose.[/QUOTE]It is used only for the "flash to pass" function. <div class="ubbcode-block"><div class="ubbcode-header">Quote:] However, there is no such wire available to connect under the dash--that I can find. [/QUOTE]Sorry, I can't help there. The other end of that wire should connect at the fuse block. I have no idea why the factory made it green w/brown ... seems like it should be solid green. You might check at the fuse block to see if there are 3 green wires, one of which has a brown tracer; as it wouldn't be the first time that the actual cars don't match the factory diagrams.

 

[KVH]

It's incredible learning from you and others on this Board!

OKAY, so the brown wire I can forget. Flash to Pass isn't anything I need, so I'll protect the end and let it dangle.

On that rheostat, can't I just byapss it permanently? Would that really cause a fuse to blow?

My guess is that the rheostat is bad because it does absolutely nothing when I turn the knob.

Thanks again. . .

 

[TR3driver]

On that rheostat, can't I just byapss it permanently?

Sure, no problem.<div class="ubbcode-block"><div class="ubbcode-header">Quote:] Would that really cause a fuse to blow?[/QUOTE]Not unless there was a short (perhaps intermittent) in the dash lights.

My point is that the rheostat tends to be the weakest link; if there is a short in the dash lights it will usually cause the rheostat to burn out instead of blowing the fuse. If you then simply replace the rheostat, it just burns out again. If you bypass it and the fuse blows, that tells you there is a short somewhere.

Last time I had that problem, it was an unused wire that got pinched between the center console and the trans tunnel (on a Stag). The wire would only short when going around a hard turn (or something like that). And that rheostat is still bypassed :laugh:
<div class="ubbcode-block"><div class="ubbcode-header">Quote:]
My guess is that the rheostat is bad because it does absolutely nothing when I turn the knob.
[/QUOTE]
My way of thinking: that makes it more likely that it is something else. But it's still a good idea to bypass the rheostat while testing. And if that proves to be the only problem, you can just leave it that way.

 

[KVH]

Another question:

When does one suspect the voltage stabilizer in a case like this?

 

[TR3driver]

The voltage "stabilizer" only supplies power to the fuel and temperature gauges. So if they are both doing something odd like reading high, or zero all the time, the VS is a likely culprit.

But it's not involved in turn signals, or dash lights; they should still work fine no matter what the VS does.

 

[Geo Hahn]

...I would suspect the flasher itself. There seem to be several flashers being sold as correct for our cars that don't actually work correctly...

If you find it is the flasher I have an extra one on the shelf you can have. Usable FLAPS version, only pulled it off because I found a correct NOS Lucas unit at Ernies.

 

[KVH]

Geo, thanks. It was the flasher, at least that part of the problem. The rest appears to be bad ground wires. Surprisingly, the ones to the dash gauges are corrupt at the eyelet connector. I'm fixing that now.