Power to tachometer
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Joined: Apr 2010
Posts: 1,198
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From: Armstrong B.C.
Car: 1991 camaro Z28
Engine: Forged 370" LS turbo s488
Transmission: Built 4L80e FTI converter
Axle/Gears: MWC 9" 35 spline 3.25 gears
Power to tachometer
Hey guys so I'm trying to finish up the wiring in my 91 Z28 that's running a Dominator ECU. So my tach worked just fine with the factory ignition and Holley HP system. I'm trying to figure out if there is a power wire I need to add or something to get it to work with the Dominator. My main harness has a blue/white stripe wire that's for tachometer output but when I hook that up to the white wire I've got nothing. Any ideas where I should look first?? Thanks guys
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Joined: Sep 1999
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From: Colorado USA
Car: '83 Firebird (T/A Clone)
Engine: 350 with L-69 components
Transmission: 700R-4, 2000 RPM stall converter
Axle/Gears: 10-bolt/3.73 ..
Re: Power to tachometer
The tach never ran off the ECM to begin with. I don't know why it would have to run off the Dominator ECU. The tach gets its power from the same place as the rest of the gauges, and the signal from the white wire connected to the ignition coil...
Joined: Mar 2001
Posts: 10,412
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Car: '89 Firebird
Engine: 7.0L
Transmission: T56
Re: Power to tachometer
HP and Dominator have the exact same pinouts for J1A / J1B connectors. Your tach should work the same. You can plug in the same harness and literally all you need to do is bring up your HP file and change the ECM setting from HP to Dominator in the ECU config.
LS engines don't have a distributor. 
The tach is driven by the ECU, output J1A-28
The tach is driven by the ECU, output J1A-28
Last edited by QwkTrip; Apr 23, 2022 at 10:50 PM.
Supreme Member
Joined: Sep 1999
Posts: 3,011
Likes: 816
From: Colorado USA
Car: '83 Firebird (T/A Clone)
Engine: 350 with L-69 components
Transmission: 700R-4, 2000 RPM stall converter
Axle/Gears: 10-bolt/3.73 ..
Re: Power to tachometer
HP and Dominator have the exact same pinouts for J1A / J1B connectors. Your tach should work the same. You can plug in the same harness and literally all you need to do is bring up your HP file and change the ECM setting from HP to Dominator in the ECU config.
LS engines don't have a distributor.
The tach is driven by the ECU, output J1A-28
LS engines don't have a distributor.
The tach is driven by the ECU, output J1A-28
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