A couple of times in the last few months I've reached down to close the driver's window without looking and inadvertently hit the 4-way flasher switch instead of the window switch. When I activate the 4-way switch and then turn if off, my turn signals won't work. If I spray some electrical cleaner around the switch, the turn signals will start working again. Can anyone who has had the switch apart explain what is going on?

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

The turn signals route through the 4 way flasher switch. Sounds like you need to take it apart and clean it.

-J

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1991 350SDL. 230,000 miles (new motor @ 150,000). Blown head gasket

Tesla Model 3. 205,000 miles. Been to 48 states!
Past: A fleet of VW TDIs.... including a V10,a Dieselgate Passat, and 2 ECOdiesels.
2014 Cadillac ELR
2013 Fiat 500E.

I too assume when you disturb the switch it is remaining open. Or the internal resistance is so high the flashers time constant with the bi metallic element becomes non functional as it can no longer heat up enough to move. This because of low current or no current.

Either dirt or oxidation is the probable villan as general wear is not very likely in that switch. Maybe it had too many coffees over the years dripped on it and is gummed up pretty bad. A good cleaning with the switch removed might just repair it. You have already found that hitting it with cleaner while installed is not doing it.

Yup. Every few weeks my turn signals stop working. I turn the flashers on and off a couple of times and they start working again. I'll do a more permanent repair on it one of these days.

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Whoever said there's nothing more expensive than a cheap Mercedes never had a cheap Jaguar.

83 300D Turbo with manual conversion, early W126 vented front rotors and H4 headlights 400,xxx miles
08 Suzuki GSX-R600 M4 Slip-on 22,xxx miles
88 Jaguar XJS V12 94,xxx miles. Work in progress.

Cleaning the Hazard switch
PeachPartsWiki: Cleaning the Hazard Switch

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1985 300SD
1983 300D
1984 190D
2003 Volvo V70
2002 Honda Civic

https://www.boldegoist.com/

Flasher relay also controls turn signals on some models.

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-- Chris

'95 E300, 216k miles, Silver Surfer
'05 E320 CDI, 138k miles
'07 S550 4matic, 69k miles

Gone but not forgotten:

'76 300D, 350k miles?, SOLD in 1995
'75 240D, 300k miles, SOLD in 1991

Wonder if it would be simpler to drill a small hole thru the switch and spray a bunch of electrical cleaner deeper down inside since the little bit that migrates inside from the sides seems to solve it in my case.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13