Weird headlight happenings

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ian65
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Weird headlight happenings

Post by ian65 » Thu Jul 14, 2016 10:09 pm

Sometimes when I've turned my headlights on and they raise, when I switch them off again they take a while to go down..... sometimes 10 seconds, sometimes it's a hour later after I've locked the car and left it.
Any ideas what could be causing this and how to fix it?

KiwiDave
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Re: Weird headlight happenings

Post by KiwiDave » Fri Jul 15, 2016 2:26 am

ian65 wrote:Sometimes when I've turned my headlights on and they raise, when I switch them off they take a while to go down..... sometimes it's a hour later Any ideas what could be causing this?
Viagra? :D
1985 Sunrise Red S3 TWR
2003 Mercedes E320 CDI Estate AMG

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ian65
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Re: Weird headlight happenings

Post by ian65 » Fri Jul 15, 2016 5:09 am

KiwiDave wrote:
ian65 wrote:Sometimes when I've turned my headlights on and they raise, when I switch them off they take a while to go down..... sometimes it's a hour later Any ideas what could be causing this?
Viagra? :D
You mean to take my mind off my headlights? :D

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KYPREO
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Re: Weird headlight happenings

Post by KYPREO » Fri Jul 15, 2016 5:43 am

Separate power wires trigger the "up" and "down" functions of the headlight. A delay in the headlight retractor suggests a poor connection in the circuit triggering the down signal. When the car is warm, resistance increases resulting in poorer quality signal/lower current/voltage. As the car cools, the signal is restored enough to excite the "down" trigger on the relays (which are attached to the side of the headlight motors).

There is a common power circuit for both headlights, but it splits in a brass connector located in the wiring harness down near the RH strut tower. This brass connector commonly corrodes over time and is the source of lots of headlight gremlins. When you open up the loom you usually find a bunch of green buildup and that's the culprit.

The fact that your problem affects both sides suggests a problem further upstream - so it's not this connector or the headlight motors or relays.

I would be looking at the headlight switch (it is common for the headlight component of the combination switch to carbon up over time) or the fusible link for the headlights. These are the most likely candidates so start there.

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ian65
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Re: Weird headlight happenings

Post by ian65 » Fri Jul 15, 2016 6:44 am

KYPREO wrote:Separate power wires trigger the "up" and "down" functions of the headlight. A delay in the headlight retractor suggests a poor connection in the circuit triggering the down signal. When the car is warm, resistance increases resulting in poorer quality signal/lower current/voltage. As the car cools, the signal is restored enough to excite the "down" trigger on the relays (which are attached to the side of the headlight motors).

There is a common power circuit for both headlights, but it splits in a brass connector located in the wiring harness down near the RH strut tower. This brass connector commonly corrodes over time and is the source of lots of headlight gremlins. When you open up the loom you usually find a bunch of green buildup and that's the culprit.

The fact that your problem affects both sides suggests a problem further upstream - so it's not this connector or the headlight motors or relays.

I would be looking at the headlight switch (it is common for the headlight component of the combination switch to carbon up over time) or the fusible link for the headlights. These are the most likely candidates so start there.
thanks for the comprehensive reply.... that's given me plenty to check out.... cheers 0-0

codge
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Re: Weird headlight happenings

Post by codge » Fri Jul 15, 2016 11:44 am

Gus does the same thing.....only it's after a few seconds rather than minutes so I haven't bothered unduly.
It's always worse after long periods of inactivity......it starts to show up on first uses as the nights draw in.

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ian65
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Re: Weird headlight happenings

Post by ian65 » Fri Jul 15, 2016 12:13 pm

Same here, if I use it frequently it seems ok

Threesevens
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Re: Weird headlight happenings

Post by Threesevens » Fri Jul 15, 2016 6:16 pm

Yeah, use it or you lose it!

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