I was replacing the gauge circuit board for a friend on his 300D, as the oil pressure gauge was leaking. The instrument lights worked just fine before replacing the unit with one from a wrecking yard. After replacing the board, the instrument lights do not work. I powered up the lights via the third pin (+) up on the left side (screwdriver pointing to the pin), and the lights glow like they should. I also powered up the bad board, and the lights work as well. When I plugged in the multi-socket connector, the lights do NOT light. I then checked the sockets with a meter, and the second socket has the power for the instrument lights (meter reads zero volts when light switch is turned off). What is up? Both the new and old board respond the same when power is applied to the third pin, so I would think that the third socket in the connector should be the one to supply power. I am not sure what to do, so I sent the guy home without working instrument lights.

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All Diesel Fleet
1985 R107 300SLD TURBODIESEL
2005 E320 CDI (daily)

LOTS of parts for sale!


EGR block kit
http://www.peachparts.com/shopforum/diesel-discussion/355250-sale-egr-delete-block-off-plate-kit.html

1985 CA emissions 617 owners- You Need This!
Sanden style A/C Compressor Mounting Kit for your 616/ 617 For Sale + Install Inst.

Sanden Instalation Guide (post 11):
http://www.peachparts.com/shopforum/diesel-discussion/367883-sanden-retrofit-installation-guide.html