Electrical Mystery

[Richard71]

Hello All,

 

I have an issue with my windscreen washer operation, I'll explain the best I can.

 

Column mounted switch, push-in type, I've proved it works by bench testing it with a multimeter.

 

Connected it back into the loom and nothing.

 

Using a power probe applying 12v at source (switch) and the pump works just fine, thus proving all wiring & the motor is fine.

 

So to me it only points to the switch, but as said, it bench tested okay.

 

Any ideas???

 

Regards,

Richard.

 

P.S.

Does anyone know where I can get a reliable Clear Hooters type dash-mounted rocker switch? The one I have (bought new from eBay sometime ago) has proven duff at first use.

[Steve T]

Hi Richard,

It's a bit fiddly, but you can part the Clear Hooters switch and clean the contacts as it sounds like you may have a high resistance fault in it.

[Richard71]

Hi Richard,

It's a bit fiddly, but you can part the Clear Hooters switch and clean the contacts as it sounds like you may have a high resistance fault in it.

 

Thanks Steve,

 

But that's just part of the problem as I'm only getting around 9v to the sidelights, the other problem is when the headlight function is selected there is play in the switch itself, i.e. the rocker switch is actually rocking, you have to hold it steady for it to illuminate the lights.

 

Not really worth the bother repairing me thinks.

 

Thanks anyway.

Richard.

[RogerH]

Hi Richard,

your test has shown that 12V can get to the washer from the switch but have you got 12V at the switch from the loom.

 

Roger

[Richard71]

Hi Richard,

your test has shown that 12V can get to the washer from the switch but have you got 12V at the switch from the loom.

 

Roger

 

The short answer Roger is "yes", I applied the 12v to the green/black wire at the switch, voila, water, water everywhere. Continuity all check out good, can't get my tiny mind around this one!

 

Richard.

 

Edit; Misread your post Roger, will try that now and report back.

 

Richard.

Edited May 6, 2017 by Richard71

[Richard71]

Hi Richard,

your test has shown that 12V can get to the washer from the switch but have you got 12V at the switch from the loom.

 

Roger

 

Thanks Roger, ignition on, no voltage at green/brown wire at either end. Fuses all check out okay, new harness from Autosparks.

 

Where should I look now?

 

Richard.

[DaveN]

Presumably a TR6? 1971?

Should be a double white wire to one of the fuses. A double Green wires one goes from there one of which goes to the voltage stabiliser terminal B and from there to the washer switch!

Edited May 6, 2017 by DaveN

[Richard71]

Hi Dave,

 

I should have mentioned, it's a late 1972 TR6, closest corresponding wiring diagram I've ever been able to find is the U.S. 1973 spec. I do indeed have two white (ignition fed) wires at the fuse box feeding 4 green wires sharing the same fuse, one of those green wires (according to said diagram) does feed the voltage stabiliser and from there as you say the washer switch.

 

I can confirm the stabiliser works as the fuel & temp gauges work.

 

What are your thoughts?

 

Richard.

Edited May 6, 2017 by Richard71

[DaveN]

Ok, so from the voltage stabiliser to the washer switch the wire could be open circuit. So first thing disconnect the voltage stabiliser 'double' green wire from the voltage stabilizer and the washer switch and do a continuity check. If that's all ok check that the voltage regulator is connected the right way round.

 

Dave

[Stanpartmanpartwolf]

The stabilised supply can't cope with the current required to power the pump- it is for gauges only.

Use the non-stabilised fused green supply instead & it'll work.

[Richard71]

Ok, so from the voltage stabiliser to the washer switch the wire could be open circuit. So first thing disconnect the voltage stabiliser 'double' green wire from the voltage stabilizer and the washer switch and do a continuity check. If that's all ok check that the voltage regulator is connected the right way round.

 

Dave

 

I've now refitted the switches after removing for other reasons and re-tested things.

I'm using the column mounted stalk switches from Revington TR (thought they'd be a good upgrade, see pic).

 

Dave,

The voltage stabiliser to the switch is indeed open circuit, in fact there is no circuit, The light green/black simply runs direct between the switch & pump motor, for some unearthly reason the loom manufacturer never put a 12v supply in.

 

In short, with everything connected and the switch is made the light green/black goes to earth.

 

My question now is, how do I energise the light green/black wire with 12v and have a functioning wash circuit?

I'd like to achieve this without unsightly wiring and the use of "Scotch Locks" (I hate those things).

 

Please see attached pics of the light green/black & earth at the column switch and another of where the wash/wipe switch tails connect with the loom.

 

Regards,

Richard.

[DaveN]

Richard

That green with a black trace and the black wire look like they terminate at the same place on the switch. Surely that can't be right?

I'd be questioning that switch to start with!

 

Don't use scotch locks, if you have to splice into the loom, use bullet connectors and solder rather than crimp unless you have quality crimp tools

 

 

As regards the voltage at the side lights, with all the filaments removed is it still only 9v? With a fully charged battery I'd expect at least 12v.

[Richard71]

Thanks for the reply Dave.

 

The light green/black & black don't actually terminate at the same place, open circuit until the switch is operated.

 

My idea now is to remove the black earth wire at the plug connection (see pic) and in its place run a wire from "B" terminal on the stabilser, that'll give me my 12v supply and the circuit complete with earthing at the pump motor.

 

Does that sound correct?

 

Richard.

[DaveN]

Er.... black is ground...earth! Ok, so a wire from the B terminal to the pump motor and it will run continuesly. So your +12ve needs to go to the switch, then all should be good. You do have continuity from the pump motor to ground?

 

Where does light green/ black come from? I thought dark green comes off the back of the stabiliser. Stabiliser light green goes to the gauges and light green/ blue goes to the washer switch?

Maybe Revington have their own colour scheme?

Anyway what you propose should work!

[Richard71]

Yeah Dave,

Any drawing I've seen shows a dark green 12v feed from the stabiliser to the switch then light green/black from the switch to the motor.

That's why I intend to replace the ground at the switch with a dark green feed from the stabiliser.

[DaveN]

Probably a bit late now but have you spoken to the loom supplier?

[Richard71]

I have,didn't help much.