Rear flasher problem

[les]

I'm sure I had this fault before, and solved it by renewing everything but it has returned. The rear n/s indicator not working, however with a meter across the centre contact of the bulb holder and earth I get an on/ off pulse in time with what would be a flashing bulb but putting the bulb back ( good bulb ) -- Nothing. Could the load from the bulb be too much, perhaps pointing to the flasher unit? Incidentally how do I check this unit? Can I join some of it's wires and get a particular reaction?
Latest situation is no indicator bulbs now operate. I personally suspect the flasher unit, any ideas please?

[Trickydicky]

Hi Les, connect all the connections from the flasher unit together and all the indicators should light up showing a good circuit. If they do then it is the flasher unit that is faulty.

[les]

Great, thanks for the quick reply, that's the test I'm looking for!

[les]

Just popped out to try the test. The only thing to light up was the end of the indicator stalk!

[bmcecosse]

And that's with the flasher out of circuit? Something serious going on with the wiring! Is it same both sides?

[les]

Yes, weird really as last time pickup was out all was ok, and not touched in the meantime. Fault started as just rear n/s not working but after pulling the rear holder out to check connections, which were ok, none of the bulbs lit. I might have accidentally shorted the live and earth in the holder but fuses still ok. Mystery.

[bmcecosse]

Probably an earth problem in some way - work at it without the flasher unit in circuit till you get all lights coming on when you move the lever.

[les]

Yes I'll link the wires more securely before I start, then go through the circuit.

[Trickydicky]

You could have a wire chafing somewhere and shorting to earth les.

[bmcecosse]

If all have now failed - need to consider possibility of a bad feed into the switch on the column...

[les]

I have an update on this issue, the 3 wires from the flasher unit when joined, light both o/s lamps when activated via column switch. When switched to n/s only front lights up. However with meter across rear holder I've got 12v. When separating the 3 wires and re-connecting the flasher unit, all ok apart from this rear n/s. Again if I use a meter I get 12v pulsing, as one would expect. Insert the bulb and despite the 12v--- nothing!

[biomed32uk]

Are you using a digital meter to test the voltage ?.

If you have resistance in the circuit (a bad connection) it wont notice on the meter as the current draw is nano amps, so you will get 12volts no problem. Put the 21watt bulb in and its now just shy of 2 amps, so may be dropping volts across a bad connection.

If the meter you have has an ohms range on it measure the resistance from the centre pin of the bulb holder back to the output side of the flasher, with the switch in the NS indicatoing position it should be pretty close to 0 ohns. I would disconnect the battery first before doing this.

The wiring to the nearside comes across the boot from the loom coming in on the offside, there is a cluster of bullet connectors there and these are good at giving bad connections. I am not sure where the wiring splits at the front of the car to go to the front indicator, only seem to remember seeing 1 wire at the bullet connectors to the switch.

If you find you have resistance from the lamp holder you can find the NS indicator wire here and measure again, so narrowing down where fault lies.

If lived nearer I'd sort it for you.

[les]

Thanks for your detailed procedure, it makes good sense and I will be following it tomorrow. I'm using an analogue meter.

[bmcecosse]

Bad earth - check with a bulb connected to the pulse - and a GOOD earth....

[les]

Ok plenty to check out now, thanks. Fault showed up as I was running a test just prior to arranging an Mot!

[biomed32uk]

Good point about the earths, as BMC says just earth out the holder somewhere. Sure you said it wasn't a saloon as with the combined lamp cluster a stop tail working would prove the earths.

Another use for the ohmmeter, measure the resistance between the lamp holder and the body, should be 0.

An analogue meter will still still read 12 volts even with a bad connection, they do pull some more current than a digital meter , for we are doing with cars it doesn't make too much difference.

I'm sure you've got a high resistance connection somewhere. I like finding and sorting electrical faults, but that's my trade. I had to tidy lots of wiring up on Maisie.

Good luck sorting it out.

[beero]

I had this with a front light. The spring that pushed the centre connector against the bulb had rusted so when the bulb was in it was not reaching the centre contact. Compare it to the other side to see if the spring has failed or solder a bigger blob of solder onto the bulb, may get you through the MOT.

[bmcecosse]

The confusion here is that we were led to believe all the flashers had failed - now we know that's not the case - it may very well simply be a dodgy lamp unit, or even a faulty bulb......

[les]

Yes I accept I did somewhat confuse things but there was a stage where all indicator lamps did not work. Maybe from the process of removing various wires. However now the fault remains as mentioned in my latter reports. Thanks for all the imput, will be out there again today!

[les]

Resistance between centre pin of holder and outer case ---5 ohms. Same reading between centre pin and good earth (body)
Will have to do some wire connection tracing.