Headlights

[manningpaul]

Had an interesting trip back from Swindon last night

Jumped in the car, started fine, put sidelights on while belting up etc. Then switched headlights on and nothing apart from sidelights. Tried rocking the switch on and off but still nothing, flash facility worked fine so decided I couldn't wait for AA and drove home keeping my finger on the flasher, getting the odd flash from oncoming and staying well back from traffic in front. Fuses all ok, changed switch over and still no headlights, next suspect is the relay, anyone know which of the three is headligts? Other than that I guess it must be wiring. Any suggestions?

Regards Paul.

[John Vine]

What year and model?

JV

[Jonathan Kay]

1. As John says.
2. Then you need the appropriate diagram once you've identified which it is.
3. Do you have a multimeter?

Jonathan

PS: I'd bet on the relay too, assuming that there's been no relevant recent work...

[SM25T]

Bet it will be the light switch or main-dip switch. Once you work out the 12V feed path through them you should soon find out where it stops.

[manningpaul]

Thanks chaps, it is an early K series SV

I have a multi meter but embarrassingly not sure that I know how to use it!!

Away at the moment but back tonight so might have time to investigate further

 

[Jonathan Kay]

Do you need the diagram? Send me a Private Mail with your email address.

I have a multi meter but embarrassingly not sure that I know how to use it!!

You soon will! :-)

Jonathan

[Golf Juliet Tango]

Bet it will be the light switch or main-dip switch.

If it applies to both sides, I agree. 

[polainm]

Relay. Pull out each relay one at a time, and check operation of hazards and starter motor. When neither of these are affected, that is the headlight relay. Take part to Halfords etc, match pin type and rating.

A multimeter will only help if you know where to poke, but you have your indication via headlights.

Could be loose wire/earth problem to relay, and relay is OK.

Fister HW514 5pin 12v 30A changeover relay. <£4 off eBay.

Also known as:

Hella 4RD 003 520 081
Hella 4RD 003 520 088
Hella 4RD 003 520 131
Hella 4RD 003 520 137

Bosch 0 332 204 101
Bosch 0 332 204 113
Bosch 0 332 204 115
Bosch 0 332 204 125
Bosch 0 332 204 150
Bosch 0 332 204 801

Leyland Auto MAG3004

​Rover YWB 10032L

VAG 443 951 254 A

[Jonathan Kay]

We agree on the probable cause and that might well be the fastest path to a solution. But I'd encourage anyone to debug logically because doing it that way you learn to solve other problems.

In this case that might be something like:

1. Get the diagram and identify the wires at the switch and the relay of interest.
2. Inspect and wiggle the wires at the switch. 
3. Check that there's 12V between the feed terminal of the switch and a good earth. That requires setting the multimeter to a suitable DC voltage range.
4. Observe the voltage at each of the two output terminals of the switch. If they both go live when they should the switch is OK. If one doesn't then remove the switch and check continuity on the bench (different range on the multimeter). Connect a different switch (doesn't need to have two different outputs for this test) and check that it goes live and whether each set of lights come on.
5. If the switch was OK then remove the relay, have a look at the pins, clean them if necessary and reinsert it. 
6. If 5 didn't fix it then see if one of the other relays looks as if it's the same. Swop them and see where the fault then appears.
7. Buy the new relay.

Jonathan

PS: NB Club discount at Halfords. :-)

[Ian B]

Paul, check the dip/main toggle isn't "half-way", and then check the connections to the rear of it. 

You can usually hear if the relay is operating (not necessarily making contact but the coil is operating) when you switch the lights rocker from side to headlights.