Trafficator Working Voltage

[Colin Morgan]

Hi,

On my Ruby at the moment, it seems that when the headlights are turned on (engine not running, battery only) the trafficators do not wish to work.  They work fine with no lights or just the side lights on.  I was therefore suspicious of the voltage that the trafficators were seeing with lights on or off and took the following readings (which are rounded a bit for clarity).

Voltage measured directly across battery terminals:                              6.5 volts

Voltage at trafficator junction box with trafficator on and lights off:         6.0 volts

Voltage at trafficator junction box with trafficator on and sidelights on:    5.5 volts

Voltage at trafficator junction box with trafficator on and headlights on:   5.0 volts

My question is, where is the resistance likely to be that is causing this voltage drop, please?  Could it be PLC switch?  Or the connections to the ammeter, for example?

[Rick F]

The trafficators on both my van and Opal will only extend fully with the engine running and chargeing. With engine off they get to about 45 degrees.

[Peter Naulls]

I got very similar figures to yours Colin and, as Rick says, they only work with the engine running. I tried cleaning all the contacts I could get to but it didn't make any difference. Making sure the trafficator mechanism is clean and properly lubricated might help a little.

[John Cornforth]

Hi Colin

The common wiring shared between the Headlights and the Trafficators (negative earth) is:

1 Main thick starter cable from Battery positive to Starter Motor Switch
2 Link from Starter Motor Switch to Ammeter
3 Ammeter to input of PLC switch
4 Earth link from Body/Chassis back to Battery negative

If the starter turns over OK you can discount No 1 above. I suggest you check the rest. Number 4 can give problems with anything that earths via the body/chassis, but it won't affect ignition, starter motor or generator as these all earth directly back to the battery via the thick starter negative cable.

It's important when chasing this type of effect to generally keep the negative end of your meter fixed on one point, e.g. the earthy side of the battery. You are then always measuring relative to the same place.

The exception is when you are particularly interested in the voltage drop across a particular component, in which case put the probes either side of that component and see what the voltage drop is when carrying current. For example to test No 4 above, connect one probe to battery negative and the other to the body, then turn on the headlights.

[Colin Morgan]

Thanks for all the replies - I will have a look.

[Tony Griffiths]

Might this just be a bad earth? I don't know if this will help - but as our Ruby wiper motor was rather sluggish I made up a new connection - fused - direct to the battery terminals. The result was a most satisfactory, high-speed metronome. Can you earth the trafficators direct to the battery negative terminal as a start? Just a temporary wire in place would enable you to check.

[Colin Morgan]

Looks like the connection where the wire comes from the back of the ammeter has been running warm - will investigate.

[Colin Morgan]

Cutting back the wire where it leaves the ammeter and soldering the end before putting it back again has improved the voltages seen at the trafficator junction:

                                                                                                      Before               After Improving Ammeter Connection

Voltage measured directly across battery terminals:                              6.4 volts             6.3 volts

Voltage at trafficator junction box with trafficator on and lights off:         5.7 volts             5.9 volts         

Voltage at trafficator junction box with trafficator on and sidelights on:    5.4 volts             5.6 volts

Voltage at trafficator junction box with trafficator on and headlights on:   4.9 volts             5.4 volts


The trafficator now works without the engine running with the headlights on. 

Thank you for the help.