tach installation
Fleet Owner
Joined: Jan 2004
Posts: 26,007
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From: Brentwood,CA
there should be 4 wires. the instructions are also in the box. one goes to ground.one to a switched hot wire , one goes to the dash lights and the ohter goes to the negative side of the coil it may be marked tach test.
Freshman User
Joined: Sep 2005
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If you have your dash open, just tap on to the radio wires. All you'll have to do is run the green wire to the ground side of the coil. You might be able to tap the coil wire right under the dash. All you have to do is trace the wire (even though they split at one point).
Here are the colors for the radio:
blue = dash lights
black = ground
yellow = live 12v source (dont tap on the wire that is hot at all times)
Here are the colors for the radio:
blue = dash lights
black = ground
yellow = live 12v source (dont tap on the wire that is hot at all times)
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Senior User
Joined: Jun 2005
Posts: 187
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From: Bloomington Indiana
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Freshman User
Joined: Sep 2005
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Ya, I'm pretty sure. If not, just test which wire is live with the key to the off position. That's the one you DON'T WANT! So just take the other wire (it really should be yellow or red) and tap your red wire onto it. Then, find a blue wire that goes to the heater or the radio or any other component that illuminates and tap the white wire onto that one (make sure that it is live with lights on and cold when lights are off). The only thing left is to find the wire that comes from the ground side of the coil. If you don't want to take a chance tracing it inside, just bring your green wire through the firewall and tap it right next to the coil. You can't go wrong.
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Senior User
Joined: Jun 2005
Posts: 187
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From: Bloomington Indiana
this installation is nowhere as easy as you guys say it is, there are three wires leading from the coil to the power distribution box, there is no way of telling the tach signal in the instrument cluster harnesses, do you know the exact color of either the tach wire in the harness, or the color of the signal wire from the coil?
New User
Joined: Jan 2006
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On the coil there should be 2 harnesses that plug in to it. The one you want is the one closer to the passenger side of the truck and it is the wire closest to the front of the truck in that harness. It should be tan with either a yellow or white stripe. (I couldnt tell for sure since it is dark outside right now)
As for the other 3 wires on the tach, I just hooked mine into the fuse panel..the red one goes to a circuit that is hot when the igniton is on, the white one goes to the dash light or tail/parking light circuit, (if you hook it into the dash light circuit, the tach will get brighter/dimmer with the dash lights when you adjust them) and the black wire hooks to any place that is a good ground.
As for the other 3 wires on the tach, I just hooked mine into the fuse panel..the red one goes to a circuit that is hot when the igniton is on, the white one goes to the dash light or tail/parking light circuit, (if you hook it into the dash light circuit, the tach will get brighter/dimmer with the dash lights when you adjust them) and the black wire hooks to any place that is a good ground.
Elder User
Joined: Nov 2005
Posts: 733
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sounds like the hot wire that you wired the tach into was also somehow connected to the blinkers, just run a new wire and it should solve the problem. i did that with my brakes on accident once... should have seen the cops face when he tried to tell me why he pulled me over, "there's something wrong with your lights, they uh... well, there is something wrong with them..."