hi

i just bought a rare accessory tach (the small gauge) off of ebay

i wired it up (pretty sure correctly) all the other gauges i've installed worked and continue to work after taping into the 12v, ground and brown light bulb wires.

but for some reason this gauge wont work. are there any usual culprits ? like a resistor i can swap out or a test i can do to check if in fact it's the gauge that is broken or if it's the red/white signal wire that is faulty behind the dash ?

what would be the next thing to check here.

i once bought a oil pressure sender from a guy who put a volt meter on the body and the gauge wire terminal and said if the resistance was infinity it's broken but if you can get a reading its working fine. Is there any similar test for these small gauge tachometers ?

You also have to provide 12 volts to the tach.
Dan

Try running a wire directly from the ignition coil to the tach. Or pull the tach and test it beside the coil.

See http://www.brickboard.com/RWD/index.htm?id=1298449&show_all=1
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1980 245 Canadian B21A with SU carb but electronic ignition and M46 trans in Brampton, Ont.

the signal wire from the top of the ignition coil is good, there are two leads off the neg. side of the coil one i imagine goes to the ECU... both wires are there and not corroded.

any other ideas of how to test a rev meter rmp gauge ?

i thought it was just a plug n' play accessory,

the ebay seller sent me a video of the gauge working before he shipped it off.
i'm a little suspect of this 'extra' caution , partly cus the gauge has the metal brackets for the turbo style cluster still attached in the video and the one he sent me didn't come with those brackets at all. why keep them ? they are worthless without the gauge. i think its just a video of a rmp gauge he might have pulled off the net somewhere.

i see shops that repair VDO and antique car gauges any idea if they can test one over the counter ?

what's the next step here ? any suggestions would be great.

Do you have it wired correctly?

You need
1) 12 volts hot wire from the fuse panel to the tach.

2) red/white wire from the coil,

3) 2 - grounds, one for the tach and one for the bulb they can be spliced together.

4) 12 volts instrument light power to the bulb.

Dan