Factory Tach wiring??
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From: H'ville Tx.
Factory Tach wiring??
I have a factory tach that has not worked since I bought the truck. Today while saying many many bad words pulling out the headlight switch that burned up this morning I found the factory tach had the wire just hanging about 6'' below the tach. Anybody know what goes to what? There are 4-yellow wires----1 red wire-----1 grey wire----1 black wire. Any ideas?? The headlight switch is a bugger to get out when the time comes guys. Mine has worse problems tho--the plug is melted way gone.
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From: Quinton, New Jersey (middle of nowhere)
your tach wire does not have a plug on the end ?? just wires ?
it should have a plug that hooks up to the male part of the plug coming out of the harness, next to hood latch tied around the main harnes.
it should have a plug that hooks up to the male part of the plug coming out of the harness, next to hood latch tied around the main harnes.
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Joined: Jan 2005
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From: Buies Creek, NC
The OEM factory tachometer plug offers the following:
- 18ga Black = +12vdc for gage lights
- 20ga Orange = 12vdc Common
- 18ga Red = Switched +12vdc
- 20ga Grey w/light blue tracer = Tachometer Signal From PCM
The following schematics show where the above comes from. The images are high resolution so you can zoom in to make them out better.
OEM Tachometer ~ +12vdc f/Lights / -12vdc Common
PCM Signal To Tachometer
Switched +12vdc To Tachometer
Hope this helps.
- 18ga Black = +12vdc for gage lights
- 20ga Orange = 12vdc Common
- 18ga Red = Switched +12vdc
- 20ga Grey w/light blue tracer = Tachometer Signal From PCM
The following schematics show where the above comes from. The images are high resolution so you can zoom in to make them out better.
OEM Tachometer ~ +12vdc f/Lights / -12vdc Common
PCM Signal To Tachometer
Switched +12vdc To Tachometer
Hope this helps.
Registered User
Joined: Aug 2017
Posts: 293
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From: Utah
The OEM factory tachometer plug offers the following:
- 18ga Black = +12vdc for gage lights
- 20ga Orange = 12vdc Common
- 18ga Red = Switched +12vdc
- 20ga Grey w/light blue tracer = Tachometer Signal From PCM
The following schematics show where the above comes from. The images are high resolution so you can zoom in to make them out better.
OEM Tachometer ~ +12vdc f/Lights / -12vdc Common
PCM Signal To Tachometer
Switched +12vdc To Tachometer
Hope this helps.
- 18ga Black = +12vdc for gage lights
- 20ga Orange = 12vdc Common
- 18ga Red = Switched +12vdc
- 20ga Grey w/light blue tracer = Tachometer Signal From PCM
The following schematics show where the above comes from. The images are high resolution so you can zoom in to make them out better.
OEM Tachometer ~ +12vdc f/Lights / -12vdc Common
PCM Signal To Tachometer
Switched +12vdc To Tachometer
Hope this helps.
Registered User
Joined: Aug 2017
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From: Utah
Sorry for my stupidity in wiring and electrical, but what is a rheostat? To wire my gauge I actually need a 12 volt constant (gauge has a memory feature), 12 volt switched, a dimmer, and a ground.
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From: Looneyville, West Virginia
If you need a constant 12v key off and on you'll need to find a wire at the fuse box or take it directly off the battery.
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From: Utah
So black is ground, red is key-on power, andorange is dimmer? I think I have it right now. Would any harm be done in wiring 3 gauges to this harness if all of them have LED lights?
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From: Utah
The instructions from the gauge packaging said not to wire it to the headlight switch, because it will make it flicker.
Registered User
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From: Looneyville, West Virginia
The Max Tow gauges I have said to not wire it to the dash light wire but to use a constant 12v source from the switch, like for the park/tail lamp wire.
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From: Utah
I misread the directions. I have the GlowShift 3-in-1 gauge and it says I need a constant 12 volt switch like the radio, a ground, a 12 volt switches or key-on power, and a dimmer hooked to the headlight switch, but not a dimmer wheel. Looking at my factory tach wiring harness on my ‘93 I found it does not have the same wire colors. It has two black wires, a orange wire, and a light blue wire. I guess I will have to decipher the wiring diagram in my FSM. Electrical is not my forte, so maybe I’ll have to enlist the help of a friend who gets it.
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Joined: Dec 2007
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From: Looneyville, West Virginia
I misread the directions. I have the GlowShift 3-in-1 gauge and it says I need a constant 12 volt switch like the radio, a ground, a 12 volt switches or key-on power, and a dimmer hooked to the headlight switch, but not a dimmer wheel. Looking at my factory tach wiring harness on my ‘93 I found it does not have the same wire colors. It has two black wires, a orange wire, and a light blue wire. I guess I will have to decipher the wiring diagram in my FSM. Electrical is not my forte, so maybe I’ll have to enlist the help of a friend who gets it.
Also make sure you have the correct connector. Sounds like you might be looking at the trailer brake connector.
Registered User
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From: Utah
That is what it means. It just needs to know the lights have been switched on and then the gauge dims the light. So use a tail/park lamp wire to tap off of.
Also make sure you have the correct connector. Sounds like you might be looking at the trailer brake connector.
Also make sure you have the correct connector. Sounds like you might be looking at the trailer brake connector.
Registered User
Joined: Dec 2007
Posts: 939
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From: Looneyville, West Virginia
Yes it does. That's the orange wire.
As a general rule on Chrysler products red is battery hot, blue is ignition hot, orange is dash lighting and black is ground. There are always exceptions though.
As a general rule on Chrysler products red is battery hot, blue is ignition hot, orange is dash lighting and black is ground. There are always exceptions though.