When the indicator is used the side lights also come on

[Martin Cooper]

1989 1.6 Turbo Diesel Caravelle.
I have just failed the MOT because when the indicators flash, the side lights, back and front, of the same side, also come on as well, though not flashing. The parking light do not work.
I have cleaned and checked for continuity, all the earth spade connections at the crown connectors, behind the fuses, all ok.
The the emergency flasher is working properly and the side light problem does not occur, with the ignition switch on or off.
With the key in and turned a little bit but dash lights not on, the parking lights function.
When I take the flasher unit out, the parking lights function properly without the key.
The van is wired for a trailer and those lights behave in the same way.
The right hand leg of the flasher unit is bent (obviously doesn’t plug in) and has a spade connector with a heavy duty brown lead coming off it I don’t know where it goes. This has been like this all the 25 years we have owned the bus. I presume that this is to do with the trailer. I think that the flasher is an up grade for the extra load the trailer lights add. The flasher has 4 legs including the bent one on the right.

I think it is either the flasher unit or the indicator switch, how do I test to work out which is causing the problem? Or is there a simple solution that I haven’t thought of?

Flasher unit Hella TB 64
4DM003360-00
(4DM004-420-04)
A 71424

[marlinowner]

Well I think if the hazard lights are working then the flasher unit is OK, it is just being switched via the hazard switch rather than the indicator stalk. Can't see it being an earth problem either, the indicator switch and maybe wiring loom to column seem the most likely suspects as that is where the indicators and parking lights come together. If you pull the fuses to the sidelights/rear lights (7 for left, 8 for right) does that stop them coming on with the indicators?

[Martin Cooper]

Thank you that gives me a start for fault finding.

[Martin Cooper]

I've removed the fuses and the lights don't come on with the indicator. I suppose this means that it's not a wiring fault at the lamp end and as you say probably at the indicator switch. I find the wiring diagram really difficult to relate to the bunch of wires on the steering column, though none of the connections look lose which also points to the switch its self. Is there anything I should try before I fork out for the new switch?

[marlinowner]

Just wondering if the problem is that the supply to the parking lights is staying on rather than going off when the ignition is switched on?
It is a grey wire running from the ignition switch P terminal to the indicator switch P terminal, maybe disconnect it and see how things work?

[Martin Cooper]

Sorry to be stupid but what is a P terminal? Is it marked P or a type of termina.

[Martin Cooper]

I have a thought, as the parking light isn't working when the ignition is fully off and only works when the key starts to turn but before it is fully on, when the winker comes on as well, that sounds like ignition switch problem not indicator switch. Does that make sense?

[marlinowner]

Yes it is sounding like the ignition switch, I forgot the bit about the ignition in the first post. Doesn't really fit with the lights working properly with the flasher removed though. P is the terminal designation on the switch connectors.

[Martin Cooper]

Thank you MarlinOwner. I have disconnected the grey lead from the ignition switch and everything is working as it should, apart from the parking lights which weren't working properly anyway.
Thank you

[marlinowner]

Excellent stuff, I've been driving for 40 years and don't think I've ever used parking lights!

[Oldiebut goodie]

They are back to front anyway! Normally one indicates left to park at the kerb and then turn off ignition but the lights need to be illuminated the opposite side towards the centre of the road not the kerb.