Co-Pang-Yang

Well-Known Member
Hi all.

Well bit of a strange one with my 300tdi. Got in it one evening switched on the lights and had no dipped beam. Sidelights work, as does full beam.
Checked fuses, checked bulbs and they all work, un-bolted earths, cleaned them and re-fitted and still nothing. Changed the stalk over and no change.
Can hear relays clicking so they seem ok though I might try swapping them round and see what happens.

Any got any ideas on what it could be? Really need to fix this but have run out of ideas.

Cheers Chris.
 
Hi all.

Well bit of a strange one with my 300tdi. Got in it one evening switched on the lights and had no dipped beam. Sidelights work, as does full beam.
Checked fuses, checked bulbs and they all work, un-bolted earths, cleaned them and re-fitted and still nothing. Changed the stalk over and no change.
Can hear relays clicking so they seem ok though I might try swapping them round and see what happens.

Any got any ideas on what it could be? Really need to fix this but have run out of ideas.

Cheers Chris.
You need a new Light switch, they do wear out and need replaced:D
 
What relays would that be clicking, a standard 300 series doesn't have relays in the lighting circuit. If the relays are additions for switching spotlights then check their wiring if it's connected to the existing lighting circuit.
 
You need a new Light switch, they do wear out and need replaced:D

Do you mean the switch in the stalk? If so I tried another one and didn't solve the problem.

Discool according to the Haynes manual it does use relays for the lighting system. A couple of the ones behind the glovebox. When you switch the light switch on and off you can hear them clicking.
 
having played with the relays for all the afternoon, I confirm there is no relay involved in the lights on a 1995 300TDi, all comes from the main light switch behind the steering wheel
 
Right I'm currently experiencing the same thing mines a 200tdi and there are no relays on mine have you checked the fusible links in the engine bay for corrosion? and I'm waiting for a third switch as I hadnt noticed that Xenon bulbs had been fitted the first time I replaced it and these have caused the switch to fail again

Check and be 100% sure you have relays in your light circuit

I will be using Mad Hat Mans relay fitting thread in common faults section to make sure it doesnt happen again

Also did you check the condition of the plugs at the back of the bulbs? sometimes the earth overheats and did you do a voltage drop test just in case there is excessive resistance in the circuit caused by aged wiring.

I hope none of this is too obvious and I'm not insulting your intelligence just a few ideas!

Good luck hope yours isnt as much of a pain in the ass as mine has been.
 
So why do the relays click when I switch the lights on and off? Must be part of the lighting system else they wouldn't do anything
 
As I said mines a 1990 200 and was coming up with some suggestions of things i have checked as with you I fitted a new switch worked ok for a little while then went again checked all of the above and then found that the switch was at fault have to say that Disco wiring is ****e and it is common for it to cause resistance in the circuit causing a voltage drop.

I'd check for a voltage drop at the bulb end of the loom and make sure the switch is not at fault myself.
 
So why do the relays click when I switch the lights on and off? Must be part of the lighting system else they wouldn't do anything

Correct, but then your disco is not standard as it left the factory and has some alterations, i assume you not the original owner so you don't know the history and what electrical work has been done, you will have to have a look.

The lighting on a D1 lighting is simple as it's controlled by just one switch thats the stalk on the side of the steering wheel. You will have a dim-dip relay but that is only activated when the side lights ane on and the engine is running... unless thats been altered as well.
 
I had Disco headlights! It will be the plugs on the back of your bulbs, in the end I cut mine off and crimped in some spade connectors, never been a problem since.
 
I had Disco headlights! It will be the plugs on the back of your bulbs, in the end I cut mine off and crimped in some spade connectors, never been a problem since.
Same here one of the wire inputs was burnt looking where it may have been shorting or arcing....I put spade connectors on....
 
Cheers lads. Pretty sure I've changed one of the plugs before but I will change them for spade connectorsand report back.
 

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