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Discussion Starter · #1 ·
Previous owner didn't have tach hooked up. Probably didn't work. I sent all gauges out to be restoed. In the meantime I found brown wire bunched up under left fender, it comes out of car below booster, after that I can't find it. Brown wire comes out of 12 pin at #9 ok. All 3 ground wires connected to cowl.Printed circuit tested ok. Hooked up brown wire I found to neg side of coil.Got gauges back in and everything works except tach. I don't even know where to start :confused: Any help much appreciated
 

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The tach wire should pass through the firewall near the throttle cable. The brown wire at the cluster connector, contact #9, is the correct wire. You should be able to follow it, under the dash, to the location where it passes through the firewall. Another thing to check is the cluster connection to the circuit card.
 

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Discussion Starter · #4 ·
Well, I traced brown wire from pin #9. It continues with main harness down left side and disappears behind fuse panel. Makes me think that maybe the brown wire I found bunched up on engine compartment side near that location was the right one. Pertronix ignition with MSD Blaster 2 coil. Still should go to - side of coil tho, correct? I do get red oil lite when ignition is on. Any ideas? :confused:
 

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The brown wire that you connected may very well be the wire intended to be used for the tach. The tach wire routed through the bulkhead connector is typical of 72 Chevelle only. 70,71 tach wire was routed through the firewall separate from the bulkhead connector. Either way I suggest you make sure you have a complete circuit from the tach terminal marked COIL, tach terminal on the right/passenger side, to the - side of the coil and that you have power on the left terminal. If you have power, ground and the pulse signal form the coil and the tach is not working you should contact the restoration shop.
 

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Discussion Starter · #6 ·
You're fantastic, Elree! Now if I could only figure out what you just said! I'm a real rookie with electrical.
Distributor is very "stock" looking, no tach terminal. Coil just has + and -. Tach terminal on pass side?
 

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Discussion Starter · #7 ·
I just tried connecting a jumper wire from just above 12 pin connector, from brown wire to - side of coil. When trying to start, the tach needle starts to work but engine won't start. If I start engine and then just touch wires together, engine instantly dies. ??? :confused:
 

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Try to track down the brown wire from #9. You can remove the two screws that hold the fuse block. At the location of the fuse block screws there are two clips that hold the fuse block to the bulkhead connector. release the fuse block so you can pull it away from the bulkhead connector. You should be able to determine where the brown wire is at in the bulkhead connector. My guess is that the wire you connected to the coil - is not connected to the #9 wire and also the #9 wire may be grounded.

The tach terminals I was referring to are in the back of the tach. The right/passenger side terminal gets 12 V when the key is on, left terminal gets the pulse signal from the coil - terminal.
 

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Discussion Starter · #9 ·
Elree, you were right again! Brown wire was grounded at bulkhead connector. Tach now runs fine!
I honestly can't tell you how much I appreciate your help. I would have been tearing up the dash again! Thanks again, Dave. (DN)
 
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