Hood Tach Wiring 1975 Regal

Discussion in 'Sparky's corner' started by MNBelv57, Aug 6, 2018.

  1. MNBelv57

    MNBelv57 Well-Known Member

    Hello all. Haven't posted in a while. Hope everyone is well and enjoying the summer. I've been busy working on and having work done to my 75' Regal. I had rust on the roof repaired and had a new vinyl top put on. I replaced the trunk lid which was rusted on the lower lip and did some rust repair on the hood and primed it. I also cut a hole in the hood to install a hood tach. I have a replacement hood that is in really nice shape and I didn't want to cut that one so I figured I would just repair the rust and pitting and use the existing hood. The problem is that I can't get the tach. to work I bought it a couple of years ago and apparently there were no wiring instructions in the box. Only the template to cut the hole in the hood. There are three wires. A brown one that had a large red plastic "dual type connector on it, a black wire with a red stripe and an in line fuse and a short black wire which is obviously for the ground. I looked online and according to the old stock types of tachs on the GSX, the brown wire is supposed to go to the neg. side of the coil. I have HEI so I hooked it up to the tach. side on the distributor and then put the black wire to the gauge lights under the dash. The problem is that even with the black wire with the red stripe disconnected, the tach light still goes on and when I tried to start the car the tach. would jump all the way to the right and then back down again and the engine would not start. When I disconnected the brown wire at the distributor, the light would go off and the engine started right up. I have no idea what is causing this but I hope someone can help. Thanks in advance, Mario.
  2. ToddsGS

    ToddsGS Founders Club Member

    I believe on this particular tach you need to hook up the Black Wire with a red tracer to the Ignition Coil. (This is your signal wire)

    The Brown wire (which normally goes to the coil on other Tach's) is actually the light source so this should go to the fuse block and come on when the ignition is "on". (That is also why this wire had the Red Connector)

    Black as you mentioned is Ground.

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