Indicator Help!

[Kraken]

Ignition on, indicator stalk right, and the appropriate dash light comes on but doesn’t flash - indicating a light out.
Rear indicator comes on but doesn’t flash, front indicator does not light.
Left indicator works fine.

Checked bulb - looks okay and checked for continuity - okay.
Tried another bulb just in case - still nothing.
Checked indicator unit, 11.5v when turn signal is on.
Earth to indicator unit is okay.
Checked the + with the turn signal off and it seems to be shorting/earthing (connected to negative, whatever you call it in car terminology).
Disconnected the external connection on the bulkhead and tests okay towards the indicator unit, shorting/earthing into the passenger compartment.
Removed the steering wheel shroud and disconnected the indicator stalk, tested the green/white wire going away from the stalk and it is shorting.
Disconnected the flasher unit and tested green/white wire and shorting.

Any likely causes for this?
It could be that I’m doing something completely wrong here as electronics are not my strong point.

I am going to try a bulb at the conmector on the bulkhead just to make sure I’m not barking up the wrong tree.

Any advice is appreciated!
I feel like I may have to actually take this to somebody to look at.

[1972nail]

When you say shorting I assume you mean that there is continuity from the indicator live wire to earth? That would be correct as the live wire connects to earth through the bulb.

I would suggest that you take out the fuse box and check for corrosion on the pins. Give it and the connectors a clean as per the last magazine tips page and see what happens.

Also make sure that there is a very good connection between the bulb and the bulb holder. A poor connection is still a connection as far as a meter is concerned but probably not good enough to pass enough current to light the bulb.

[lord13]

This is on a HC right?
If so, it's usually corrosion in the weird 'mazak' stuff they used for the lamp unit, as a quick fix, and to check if that is indeed the problem, we used to make a connection by stripping enough insulation off a bit of wire to wrap around the body of the bulb, twist it very tight, then connect the other end to one of the lamp fixing screws, making sure it was a good solid connection to the body. This now becomes the earth connection, completely bypassing the spongey awful stuff the unit is made of.
If that doesn't do the trick, instead of using a meter to check for continuity etc, go old school and use an old lamp holder ( one of the rear light unit ones works great) with an indicator lamp in it, attach a couple of wires to it and use that as your test meter. It will draw the correct amount of current to trip the flasher unit and you'll be able to find exactly where it all goes wrong in your loom.

[Kraken]

I was barking up the wrong tree entirely yesterday.

Tried a bulb at a spade terminal in the engine and it works here, so definitely something at the lamp unit end.

Progress at least!

[1972nail]

Keep us informed please.

[Kraken]

It was a poor earth at the unit. I did as Mitch suggested and wrapped a wire around the bulb and into one of the screw holes for the lense.

Drove to Aberdeen, parked up and went bowling, came back to car and now I’ve lost my sidelights and headlights!

Whichever position the switch is in all lights are off.
If I pull on the stalk my main beam does come on though.
Took off the switch and bridged the wires with some pliers and still nothing so it doesn’t look like the switch.
All 4 fuses look okay.
Lights were working on my way in, at least I assume they were, the dash was lit up, which it will no longer do.

So now I’m stranded in Aberdeen tonight

[1972nail]

Sounds like the thermal cut out has decided it's had enough. Usually a clean of the contacts is all it needs. Bridging the wires on it might get you home but be careful as that's the only protection the lighting circuits have on pre 74 cars. Post 74 also have a fusible link in the lighting circuit.

Or it could be the bulkhead connector both sides of the fuse box. Check all the connections and each of the individual wires are clean and pushed home properly. You'll need something like a plastic pen barrel to push home the wires on the underside.

[Kraken]

Thanks David.

Bulkhead connectors were all checked two days ago and are nice and clean. Could still be a poor connection herr I guess.

If the thermal cutout was causing it would I still be able to flash my main beams?

Can out to the car this morning and the lights came on right away so I can’t exactly fault find!
I’m going to remove and inspect the thermal cutout though, and I think I might order up a spare to keep in the car.

[1972nail]

The 'warning flash' is independent of the cut out so it will still work OK. The cutout operates at about 23 - 28A. So I used to carry a 25A blade fuse just in case it gave me trouble. It will fit into the spade connectors on the back of the cutout. I never had to use it and looking back on it now it was not the best idea anyway as the cutout is designed to cycle on and off rapidly rather than cut completely. A lot safer as it at least it gives you some warning.

To operate the cutout there must be a fault or high resistance connection in the lighting circuit somewhere. I suspect the switch in the dash. They have a habit of burning the contacts and then eventually melting the wires and connections. However, if they haven't melted, they are easily taken apart and cleaned up. Use a bit of electrical grease or hub bearing grease as a lubricant on reassembly.

[Kraken]

Well I looked at it all today. It still puzzles me that it wasn't working that night, because surely for the thermal cutout to have triggered the circuit would have had to be on for at least a bit of time to heat up and cause it to cut?

Anyway, the thermal cutout had a slight melty/burny issue at one of the spade terminals. Cleaned this up as well as the contact points.

Removed the light switch and it actually seemed okay internally, although a bit black and sooty. All nicely cleaned up now though, and I used some GTechniq C4 blackener stuff on it while it was out. It's gone from light grey to Almost black. You can see the difference between it and the wiper switch.

Obviously I had to do the wiper switch after that!

Just need to paint the symbols back on at some point!