VW New Beetle RH Main Beam not working

VW New Beetle RH Main Beam not working

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Discussion

Falsey

Original Poster:

449 posts

138 months

Monday 17th July 2017
quotequote all
Scratching my head about this one if anyone has an idea.

Girlfriends car, had a smashed headlight, main beam not working. Swapped it out for a new headlight and the main beam still doesnt work. Swapped the bulbs around and put a known good one in there, still doesnt fire up.

Cables are the right way around, seated properly, seems all good. Headlight is seated on the mounting as far as it'll go. No warnings on the dashboard. I pulled the fuse and it looks fine to me, and the sidelights and high beams work fine anyway.

Cant really think of anything else to check with it now? Am I stuck with having to find an OBD scanner?

Thanks

E-bmw

9,106 posts

151 months

Monday 17th July 2017
quotequote all
An OBD scanner is not going to help you.

Check with a multimeter, have you got 12 volts on the correct pin of the bulb when it is switched on, also have you got earth on it's correct pin (compare to other side) I am guessing one will be missing & if you "hot wire it" it will work fine.

Sounds like you have a wiring fault.

Penelope Stopit

11,209 posts

108 months

Monday 17th July 2017
quotequote all
Falsey said:
Scratching my head about this one if anyone has an idea.

Girlfriends car, had a smashed headlight, main beam not working. Swapped it out for a new headlight and the main beam still doesnt work. Swapped the bulbs around and put a known good one in there, still doesnt fire up.

Cables are the right way around, seated properly, seems all good. Headlight is seated on the mounting as far as it'll go. No warnings on the dashboard. I pulled the fuse and it looks fine to me, and the sidelights and high beams work fine anyway.

Cant really think of anything else to check with it now? Am I stuck with having to find an OBD scanner?

Thanks
Did the main beam work before the headlight was smashed? If yes, the fuse is a very likely culprit, if no, the fault could be anywhere

normalbloke

7,401 posts

218 months

Monday 17th July 2017
quotequote all
Is this a CAN bus car? If so, one of the BCMs may have shut that circuit down, or, more worryingly, damaged the BCM.

Falsey

Original Poster:

449 posts

138 months

Tuesday 18th July 2017
quotequote all
Thanks all.

I have swapped the fuse and still no dice. I dont have a multimeter so Ill have to procure one in order to check.

Either that or convince her to scrap the bloody heap smile

What is a BCM?

Penelope Stopit

11,209 posts

108 months

Tuesday 18th July 2017
quotequote all
Body Control Module, many vehicles have them and many electrical circuits go through them so that they can interlink with other circuits/modules and also be monitored etc etc etc

Edited by Penelope Stopit on Tuesday 18th July 10:36

Mignon

1,018 posts

88 months

Tuesday 18th July 2017
quotequote all
Oh jeepers. People trying to be helpful on the intergoogles eh. If the high beam, side lights and the headlight on the other side work ok it's not fuses, Canbus or any other nonsense. You just don't have voltage to the main beam pin on that bulb. Either it's a faulty bulb holder with a dry joint or broken terminal or the main beam wiring upstream of that. Trace it back to where you do have 12v between that wire and earth and then examine what's left very carefully.

Falsey

Original Poster:

449 posts

138 months

Tuesday 18th July 2017
quotequote all
Alright. My weakest discipline is definitely electrics so I expect Ill have a lot of tracing to do smile

Penelope Stopit

11,209 posts

108 months

Tuesday 18th July 2017
quotequote all
Mignon said:
Oh jeepers. People trying to be helpful on the intergoogles eh. If the high beam, side lights and the headlight on the other side work ok it's not fuses, Canbus or any other nonsense. You just don't have voltage to the main beam pin on that bulb. Either it's a faulty bulb holder with a dry joint or broken terminal or the main beam wiring upstream of that. Trace it back to where you do have 12v between that wire and earth and then examine what's left very carefully.
Lights are fused LH and RH

Mignon

1,018 posts

88 months

Tuesday 18th July 2017
quotequote all
Penelope Stopit said:
Lights are fused LH and RH
Then why does the high beam work ok on that side? Are you seriously trying to tell us there are four separate fuses for the headlights on that car? LH high beam, LH main beam, RH high beam and RH main beam? Go on wi' yer man.

Falsey

Original Poster:

449 posts

138 months

Tuesday 18th July 2017
quotequote all
The chart seems to indicate that highs and lows are on seperate circuits.

18-23 below




GreenV8S

30,150 posts

283 months

Tuesday 18th July 2017
quotequote all
Mignon said:
You just don't have voltage to the main beam pin on that bulb. Either it's a faulty bulb holder with a dry joint or broken terminal or the main beam wiring upstream of that.
This ^^^. Un-noticed damage to the bulb holder or adjacent loom seems like the first thing to check for.

Penelope Stopit

11,209 posts

108 months

Tuesday 18th July 2017
quotequote all
Mignon said:
Penelope Stopit said:
Lights are fused LH and RH
Then why does the high beam work ok on that side? Are you seriously trying to tell us there are four separate fuses for the headlights on that car? LH high beam, LH main beam, RH high beam and RH main beam? Go on wi' yer man.
There you go, live and learn

normalbloke

7,401 posts

218 months

Tuesday 18th July 2017
quotequote all
Penelope Stopit said:
Mignon said:
Penelope Stopit said:
Lights are fused LH and RH
Then why does the high beam work ok on that side? Are you seriously trying to tell us there are four separate fuses for the headlights on that car? LH high beam, LH main beam, RH high beam and RH main beam? Go on wi' yer man.
There you go, live and learn
Perhaps he should have intergoogled it.

Mignon

1,018 posts

88 months

Tuesday 18th July 2017
quotequote all
Fair enough. Four fuses then, although I suspect even the people who thought they might be fused separately on each side didn't think they'd be fused separately for high and low beam as well. So the OP has a fuse to check first now at least. It's not completely clear from his first post whether "the" fuse he checked was the actual fuse for that specific circuit or one he thought was a main fuse for all the headlight beams. If the fuse is ok however then it's likely what I said previously was wrong.

Falsey

Original Poster:

449 posts

138 months

Tuesday 18th July 2017
quotequote all
Sorry I wasnt very clear. I was never under the impression there was only one fuse. I only mentioned the one fuse because its only the main beam affected, thus one fuse.

A friend of mine brought his OBD scanner around just for an attempt at least. When it was programmed for the Beetle it interestingly was able to scan for left and right lighting circuits seperately which I thought would be good. Then it couldnt get an OBD connection with the car no matter what we tried.

I hate this thing.

PositronicRay

26,958 posts

182 months

Tuesday 18th July 2017
quotequote all
Mignon said:
Fair enough. Four fuses then, although I suspect even the people who thought they might be fused separately on each side didn't think they'd be fused separately for high and low beam as well. So the OP has a fuse to check first now at least. It's not completely clear from his first post whether "the" fuse he checked was the actual fuse for that specific circuit or one he thought was a main fuse for all the headlight beams. If the fuse is ok however then it's likely what I said previously was wrong.
My car's 23yrs old and has separate right,left,high,low, beam fuses.

I would check power @ the fuses then work upstream or downstream depending on what I found.

Falsey

Original Poster:

449 posts

138 months

Friday 21st July 2017
quotequote all
Mrs was pulled over last night for driving with a headlight out and they wouldnt let her go unless it worked. She pushed the headlight housing as hard as she could and it came on.

Id say that its almost certainly the connector that is pooped. How Id go about replacing that I dont even want to think, but at least we know now.

Thanks.

PositronicRay

26,958 posts

182 months

Friday 21st July 2017
quotequote all
Falsey said:
Mrs was pulled over last night for driving with a headlight out and they wouldnt let her go unless it worked. She pushed the headlight housing as hard as she could and it came on.

Id say that its almost certainly the connector that is pooped. How Id go about replacing that I dont even want to think, but at least we know now.

Thanks.
Look @ the bulb type and google the connector for it. I recently swapped one (easy access on my car) so quite simple, it'd been intermittent for a little while, triggering a "bulb out" light on the dash. The old connector was burnt out, presumably from a poor connection.

E-bmw

9,106 posts

151 months

Friday 21st July 2017
quotequote all
E-bmw said:
An OBD scanner is not going to help you.

Check with a multimeter, have you got 12 volts on the correct pin of the bulb when it is switched on, also have you got earth on it's correct pin (compare to other side) I am guessing one will be missing & if you "hot wire it" it will work fine.

Sounds like you have a wiring fault.
I hate to say it........