10 replies to this topic

[Mayfair'93]

Hello everyone,

I am having trouble with the nearside rear indicator which I hope someone will be able to help with.

It seemed to start when the nearside rear brake light bulb blew. At the time all other exterior and interior lights were working (including the indicator). It was a simple bulb change.

Having replaced the faulty bulb, the nearside rear brake light is working however the nearside rear indicator now doesn't flash or light up at all. All other exterior and interior lights are still working. I have checked the bulb and it isn't faulty and I've even tried another bulb but no luck either.

The fuses look OK. Although as it is only the one indicator I'm guessing it wouldn't be fuse related?

I've cleaned all connections but that hasn't made a difference.

Could it be a bad earth?

Any ideas of what I should check first?

Cheers,

E

[richmondclassicsnorthwales]

Hi

 

What you could first try is earthing the lamp unit yourself with a piece of wire, and as the battery is in the boot, put the other end of the wire straight onto the negative battery terminal.

 

If that doesn't do anything, then go under the bonnet, and at the passenger side, on the bulkhead, you will see wires which go and connect into  bullet connectors.

These will be around the hinge area for the bonnet.

 

If I remember rightly, the red and white wire is the rear NS indicator. These bullet connectors do cloud up, and it could this.

 

Unfortunately as the petrol tank is in the way of the lamp unit, it is not as easy to check the wiring

[Mayfair'93]

Thanks for the reply, that's helpful. I'll take a look and let you know what I find.

I should have said the car is a 1993 Mayfair carb model.

[bpirie1000]

Did you check the connections on the light unit? I have seen the positive side (goes to the pointy end of the bulb) to be corroded and the spring fails making the bulb inoperative as there is a gap between the contact and the bulb it's self.

Try removing the bulb and sticking a volt metre on the terminal.... the other end on an earth point.. see what you get....

Also I believe from the model of your car you would have 2 flasher units. Are the hazard lights working?

Edited by bpirie1000, 17 October 2020 - 04:47 PM.

[Mayfair'93]

Thank you for the responses. All very helpful.

I tested the voltage on the offending bulb holder and I get just over 11v (that is with the engine off but ignition on). I get the same on the working offside indicator. I assume this is good?

The spring in the bulb holder pushes in and comes back as it should and the same as the offside which is working.

I have checked all fuses. They are all as they should be.

Yes, I have two flasher units. The hazards are working. All interior and exterior bulbs flash except for the nearside rear indicator.

Any more ideas?

Edited by Mayfair'93, 20 October 2020 - 05:26 PM.

[RustyAutoCityE]

Have you checked for continuity from the lamp holder to car ground?
I assume you have as you have checked for voltage at the lamp, but thought it's worth asking.

[weef]

Using a DVM in this instance is possibly throwing you off the scent. The DVM puts very little load on the circuit, this is the purpose of these instruments when working on delicate electronic circuits, but in this case you need to load up the circuit with a bulb or a test lamp. Using a combination of the DVM and the lamp will give a better indication to what is wrong. Measure the voltage with the DVM and monitoring this, connect a bulb/test lamp to the circuit. If the voltage collapses when the bulb is in circuit I would suspect a high resistance , check the integrity of any connectors and examine the wire as best as possible. Internal corrosion of wire is not uncommon and can lead to such problems as you describe. You could try running a jumper wire from a convenient point at the front of the car to the lamp unit to try and narrow down the fault .When carrying out these checks use the earth contact on the lamp unit and then with a good proven earth to see if there is any difference. If you are confident with fault finding you could measure the volt drop along the wire when under load. The volt drop should not exceed 0.2 volt on a healthy circuit. If the voltage is sustained when under load then look at the lampholder for a problem. .

[Mayfair'93]

Thanks everyone.

Yes, I have continuity from the lamp holder to ground.

I'll try and check using a test lamp as well.

[Mayfair'93]

In the meantime...

I measure 12v across fuse 1 and 2 (four fuse box). Does that mean there is a short circuit or am I going mad and need a break from auto electrics?!

[jime17]

If you measure 12 volts across the fuse ie. Between one end of the fuse and the other then the fuse is blown. You should only get a small voltage across a fuse which is due to its resistance causing a voltage drop. Your are measuring the potential difference between one terminal and the other.

[bpirie1000]

Try find the positive feed wire at where the front loom and rear looms join together nearer the wiper motor.

Make sure we have a good connection. Think it is coincidence that the indicator fault was at the same time as rail light bulb blew.