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Old 05-13-2013, 08:37 PM
Unregistered Abuser
Join Date: Jul 2005
Location: Eau Claire WI
Posts: 968
76 300D Dash lights inop, and turn signal doesnt stay locked in

Hello, I have a 76 300D that's having some interior lighting issues.

My dash lights (cluster, and hvac) do not work, on any setting of the dimmer. I also notice that when I turn on the turn signal, the cluster needled jump a bit in tune with the lights illuminating. To clairy, when I turn on the blinkers, the temp, and fuel needles move slightly. The other lights do not come on.
I'm on the thought process of possibly having a bad ground in the cluster, but I could also have an inop dimmer switch as well.

Any thoughts as to what could be happening?

Also, when I push the turn signal stalk down, the stalk does not lock into place as i feel it should. Possibly bad turn signal switch?

Thank you all

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)
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Old 05-13-2013, 09:21 PM
Registered User
Join Date: Jul 2008
Posts: 3,740
The dimmer aka rheostat is bad on the cluster. You will need to remove the cluster replace the rheostat or simply bridge the two contacts which will eliminate the dimmer.

You will need to replace the stalk, quite expensive for a w115 but there are some DIY repairs floating around. It is very easy to remove, replace or fix.

The jumping needles can be from the switch, bad grounds or fuses. Have you opened your fuse box and replaced all the fuses with the copper ceramic versions? That clears up ALOT of electrical problems...the original fuses were made of aluminum...aluminum and copper don't meet well...add in 30+ years....heat and moister....not good...
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Old 05-14-2013, 12:26 AM
Registered User
Join Date: Apr 2012
Location: San Luis Obispo, CA
Posts: 1,587
Turn signal:
PeachPartsWiki: Self-Canceling Turn Signal Indicator Fix

Regarding the rheostat:
Turn it back and forth MANY MANY MANY times. You can grind away the corrosion and possibly get it working. I spent a boring drive twiddling it for 10 minutes and got mine working again.

The jumping suggests that you have a grounding issue. But I think that is separate from the other problems. Good luck.
1968 220D, W115, /8, OM615, Automatic transmission.
1987 300TD, W124, OM603, Automatic transmission.
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Old 05-14-2013, 10:59 AM
Registered User
Join Date: Aug 2011
Posts: 108
The reohstat is very easy to bypass. I tried cleaning mine to no avail. I used a short section of speaker wire to bypass mine. I stripped and twisted the ends and shoved them into the rivet holes. The tension of the bend in the wire holds them in place. I removed the rehostat from the cluster in the picture to try and clean it, but it is not necessary to remove it if all you are going to do is bypass it.
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76 300D Dash lights inop, and turn signal doesnt stay locked in-mercdashlight.jpg  
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Old 05-16-2013, 12:11 PM
Join Date: Sep 2005
Posts: 664
Pelican still sells this part if you wish to just replace it with a new one.

The price is about $125, so it is worth the time it might take to clean it up and see if that fixes it before springing for a new one.

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