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73-87 Chevy _ GMC Trucks => 73-87 Chevy & GMC Trucks => Topic started by: 78K204wd on April 11, 2014, 12:08:04 pm

Title: Installing Tach in my 78K20, which color wire is on the dimmer circuit ?
Post by: 78K204wd on April 11, 2014, 12:08:04 pm

Hi, i am installing a tachometer in my 1978 K20, and I want to hook up the tach light to a wire under my dash that is on the dashboard dimmer light circuit.  So when I turn the lights on the tach will light up at night.

Does anyone know what color wire to look for under the dash? 

I really don't want to pull out the instrument panel and gage cluster again to find a wire.

Thanks

Title: Re: Installing Tach in my 78K20, which color wire is on the dimmer circuit ?
Post by: BADAZ chevy guy on April 11, 2014, 12:13:17 pm

You might be able to find it here >>> http://forum.73-87chevytrucks.com/smforum/index.php?topic=11766.0

Title: Re: Installing Tach in my 78K20, which color wire is on the dimmer circuit ?
Post by: bd on April 11, 2014, 02:13:55 pm

The instrument lamp dimmer circuit is generally gray - but, not all gray wires are dash lights.  See the 1978 Wiring Manual (http://www.73-87chevytrucks.com/techinfo/7387CKMans//Wiring/ST_352_78_1978_Chevrolet_Light_Truck_Wiring_CK_10_30_Only.pdf).

Title: Re: Installing Tach in my 78K20, which color wire is on the dimmer circuit ?
Post by: 78K204wd on April 12, 2014, 05:59:45 am

Thanks guys, I hooked it up to the fuse for the panel lights, works great now, at night.