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#1 |
Registered User
Join Date: Oct 2004
Posts: 1
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factory tach wiring
Hi folks....new to the board.Working on getting a '75 sierra 25 4x4 working after sitting in a field for the last 20+ years. Need a wiring diagram or pictures of the factory tach wiring in the engine bay. A pic of the fuse box would help also. Specific question is...does the brown wire run from underdash thru firewall to a "selinoid" on the firewall in the engine bay,to spliter plug and then to the HEI coil????Thanks again.
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#2 |
Professional Grade
Join Date: May 2003
Location: Fort McMurray, Alberta
Posts: 7,915
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If you are infact running an HEI rather than points on the truck, the white wire goes to the Coil terminal on the HEI cap, the black wire goes to the ground (the factory slot is above the kick panel on the driver's side wall, it is just bolted there and should have a couple other wires going to it already) the pink wire plugs into an ignition switched power source
![]() I can get some pictures later if you want ![]()
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1995 Chevrolet 2 Door Tahoe (6.6L LBZ Duramax / ZF6 / NP241 with 1 ton solid axle swap) |
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#3 |
Gentleman Jim Driver
Join Date: Nov 2002
Location: Poulsbo, WA
Posts: 1,550
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My crew cab has what you describe with the wire going to the coil. It is a wire that goes from the tach connection to a little metal box near the brake master cylinder on the firewall. I think it has to do with the kickdown switch on the TH400. I tapped into that wire for my tach just like you are describing.
The other possibility if that isn't what you are talking about is the little round metal can mounted on the firewall directly behind the distributor. That is a condensor (or capacitor if you want) that is there to lower the interference from the tach wire to your radio.
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Joe '75 GMC Gentleman Jim '84 Chev C10 Short Wide - Super duper plain (manual steering, manual brakes, no dome light, no cig lighter) '85 Chev C10 Short Wide - Super plain Vortec 4.8 4L60E trans also: '81 K30, '83 C30 Crew Dually, '84 M1028 CUCV, '85 M1009 CUCV, another '85 C10 SWB, '89 R3500 Flatbed |
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