Hello,

The dash lights of the instrument panel are not responding on the 76 300D. I've removed the cluster, checked the bulbs and the dimmer control. That and the circuit board for the instruments seems to be okay. I checked resistance through the rheostat and through the contacts on the circuit board. I also checked the resistance on what I thought to be the right points in the multi-pin connector that plugs into the back on the cluster. I got a reading of some resistance, but I don't know what it is supposed to be.
I wonder if the rotary light switch is not telling the cluster lights to come on. I don't know how to check for this, other than checking for voltage in the same pin holes on the multi-pin connector that I checked for resistance. I got nothing when I did that, but I don't know much about electronics.

Any help is appreciated.

Also a seperate related issue. The temp gauge bounces wildly a lot of the time now. There are two sensors plugged into the head on the glow plug side of the engine. I'm guessing it is the rearward sensor since uplugging the one in front, (that is also connected to glow plug #1) has no effect. Should I just replace the temp sensor?

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63 220S W111
76 300D W115
2013 VW JSW TDI M6

previously-
73 280 SEL 4.5
86 300E 5 speed
2010 VW Jetta TDI M6

Humm, on my W114 the temp gauge is one piece from the cluster back to the sensor in the head. Its a fairly large braided wire.

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Adam Lumsden
(83) 300D
Vice-President of the MBCA International Stars Section

You have the prior version. The one that stays on all the time. I forget the name for it now, but mine is different.

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63 220S W111
76 300D W115
2013 VW JSW TDI M6

previously-
73 280 SEL 4.5
86 300E 5 speed
2010 VW Jetta TDI M6

Turns out the fuse was blown. I don't know how I didn't see it the first time. Unfortunately, the new fuse lasted all of 8 seconds. I have no idea how to chase down something like this.

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63 220S W111
76 300D W115
2013 VW JSW TDI M6

previously-
73 280 SEL 4.5
86 300E 5 speed
2010 VW Jetta TDI M6

The fuse holder should give you a rough idea of everything connected to the fuse.
Turn everything off for that fuse and then systematically turn things on and back off, one at a time, till it blows.
If it blows without anything on, unplug the instrument cluster and try again.

Michael

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Usta haves '69 250/8, '76 280C, 1971 250C 114.023, 1976 450SEL 116.033
Current have, 1983 300SD 126.120

if you ground the wire that comes off of the sending unit, does it max out the tempature gauge in the car?

If I had a problem with mine, I'd replace the sending unit, which is $19 at fastlane.... Get the VDO one, looks alot better machiening then the FAE one (from the pics) Compair threads on the FAEto the ones on the VDO

P4036-12281 at fastlane

~Nate

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95 Honda Shadow ACE 1100.
1999 Plymouth Neon Expresso. 2.4 swap, 10.5 to 1 comp, big cams. Autocross time attack vehicle!
2012 Escape, 'hunter" (5 sp 4cyl)