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Discussion Starter · #1 ·
My rpm gauge hasn’t worked since I bought my bronco and I’m trying to figure out how it works. Also under the hood on the driver side there is some wires not plugged in to anything and there is another wire coming out of the harness beside the distributor that is red/orange and has a blue connector on it that goes to nothing so I’m also trying to figure out what those are for.
162896
162895
 

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Yo ethanwilliams125,
What year? Read How To Create A Signature @ FAQ

Inspect tachometer wires for usual suspects; corrosion looseness, frayed insulation, etc.

As a guess, attached Wiring Diagram is an excerpt from 87-89 Bronco & F series (Haynes); Source: by equivalent (Beetlejuice) @ 1985 Ford Bronco Haynes pictures, videos, and sounds | SuperMotors.net
DK GRN/YEL & BLK/YEL at Tach
View attachment 155334

Inspect instrument cluster printed circuit for damage, poor connections, or open circuits.
View attachment 155335
87-91 Tach Cluster Terminals
Try polishing the film circuit contacts with brown paper or a pink eraser, Be careful NOT to peel the copper strips off the mylar film.by Steve

A1 - Seat Belt - DG/LG
A2 - Hi Beam - LG/Bk
A3 - Ground - Bk
A4 - Illumination - LB/R
A5 - unused
A6 - Tachometer - DG/Y
A7 - V8 ground - Bk/Y
A8 - R Turn - Wh/LB
A9 - ABS - DG
A10 - 4WD - LB
A11 - Low Range - LB/Bk
A12 - Fuel - Y/Wh
A13 - Gauges & Warning Lights Power - R/Y
A14 - unused
B1 - Oil - Wh/R
B2 - Ground - Bk
B3 - L Turn - LG/Wh
B4 - unused
B5 - Gauges & Warning Lights Power - R/Y
B6 - unused
B7 - Emissions - Bk/LB?
B8 - Brake - Pu/Wh
B9 - CEL - Pk/LG
B10 - Ground - Bk
B11 - Temperature - R/WH
B12 - IMS/EUL - Wh/R?
B13 - Charge - LG/R
B14 - Ig.Sw. - R/LG

Since you didn't mention any issues with other gauges, assume Ground G701 is ok. It's s behind and right to the radio and not many here have found it.
 

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Discussion Starter · #4 ·
Yo ethanwilliams125,
What year? Read How To Create A Signature @ FAQ

Inspect tachometer wires for usual suspects; corrosion looseness, frayed insulation, etc.

As a guess, attached Wiring Diagram is an excerpt from 87-89 Bronco & F series (Haynes); Source: by equivalent (Beetlejuice) @ 1985 Ford Bronco Haynes pictures, videos, and sounds | SuperMotors.net
DK GRN/YEL & BLK/YEL at Tach
View attachment 155334

Inspect instrument cluster printed circuit for damage, poor connections, or open circuits.
View attachment 155335
87-91 Tach Cluster Terminals
Try polishing the film circuit contacts with brown paper or a pink eraser, Be careful NOT to peel the copper strips off the mylar film.by Steve

A1 - Seat Belt - DG/LG
A2 - Hi Beam - LG/Bk
A3 - Ground - Bk
A4 - Illumination - LB/R
A5 - unused
A6 - Tachometer - DG/Y
A7 - V8 ground - Bk/Y
A8 - R Turn - Wh/LB
A9 - ABS - DG
A10 - 4WD - LB
A11 - Low Range - LB/Bk
A12 - Fuel - Y/Wh
A13 - Gauges & Warning Lights Power - R/Y
A14 - unused
B1 - Oil - Wh/R
B2 - Ground - Bk
B3 - L Turn - LG/Wh
B4 - unused
B5 - Gauges & Warning Lights Power - R/Y
B6 - unused
B7 - Emissions - Bk/LB?
B8 - Brake - Pu/Wh
B9 - CEL - Pk/LG
B10 - Ground - Bk
B11 - Temperature - R/WH
B12 - IMS/EUL - Wh/R?
B13 - Charge - LG/R
B14 - Ig.Sw. - R/LG

Since you didn't mention any issues with other gauges, assume Ground G701 is ok. It's s behind and right to the radio and not many here have found it.
It’s a 1985
 

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Sometimes the tach itself can leach some sort of glue onto the circuit board and short out circuits. There’s a good tach cleaning procedure on FTE. I used it but it didn’t help my tach so I found another cluster in the JY.
 

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Discussion Starter · #7 ·
Sometimes the tach itself can leach some sort of glue onto the circuit board and short out circuits. There’s a good tach cleaning procedure on FTE. I used it but it didn’t help my tach so I found another cluster in the JY.
Ok thanks. Anybody know what those wires I posted go to?
 

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There’s unused plugs on most trucks. Your best bet is to get an EVTM for your model year and see if you can find those wires.
 
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