Tachometer woes
Thread Starter
Joined: Nov 2012
Posts: 672
Likes: 16
From: Michigan
Car: 1988 IROC-Z/G92
Engine: 5.0
Transmission: T-5
Axle/Gears: BW 3.45 Eaton Truetrac
Tachometer woes
So I just got my instrument panel back in after being out for so long, I know I need to get a new printed board for the instrument panel, but that's later.
However the tachometer is pegged. The tach worked fine when I removed it.
Would the circuit board do this? Or is it a different issue?
305 5 speed. If that makes a difference.
Thanks in advance
However the tachometer is pegged. The tach worked fine when I removed it.
Would the circuit board do this? Or is it a different issue?
305 5 speed. If that makes a difference.
Thanks in advance
Junior Member
Joined: Aug 2019
Posts: 1
Likes: 0
From: Philadelphia
Car: '88 IROC
Engine: 305 TBI
Re: Tachometer woes
The tach on my '88 Camaro is usually pegged at the top too whenever the key is on. Unfortunately it was like that when I bought it, the previous owner screwed up a lot of stuff worse while he was working on it. He said he might have put in a few connections with the wrong polarity. I haven't opened up the dash yet because it's a lower priority compared to some problems that make the car physically not road safe, but I'll watch this thread and share whatever I learn when I get to dealing with mine.
Supreme Member
Joined: Jan 2006
Posts: 3,341
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From: Mooresville NC
Car: LOWERED ♦ CRIMSON METALFLAKE
Engine: ► 400 KUBES ◄
Transmission: 765R4
Axle/Gears: EATON POSI 4.56
Tachy Indicator
There is circuitry in the dash near the tach.
It’s contained on a small plug-in PCB or integrated in the main board.
On or near the PCB you’ll see a capacitor, replace it.
Also on the PCB you’ll see a resistor chip.
Desolder pins 4 & 10.
Use a 500K potentiometer.
Solder it across traces 4 & 10.
Move the potentiometer to half way.
Start the engine and compare the tach reading with a test equipment quality tach.
Dial it in, unsolder the potentiometer, measure it and install a matching resistor.
◙◙◙◙◙◙◙◙◙◙◙◙◙◙◙
Happy Racing !
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I Smacked The Wall With The Side Of The Car Because A Narrower Car Is A Faster Car
It’s contained on a small plug-in PCB or integrated in the main board.
On or near the PCB you’ll see a capacitor, replace it.
Also on the PCB you’ll see a resistor chip.
Desolder pins 4 & 10.
Use a 500K potentiometer.
Solder it across traces 4 & 10.
Move the potentiometer to half way.
Start the engine and compare the tach reading with a test equipment quality tach.
Dial it in, unsolder the potentiometer, measure it and install a matching resistor.
◙◙◙◙◙◙◙◙◙◙◙◙◙◙◙
Happy Racing !
◙◙◙◙◙◙◙◙◙◙◙◙◙◙◙
I Smacked The Wall With The Side Of The Car Because A Narrower Car Is A Faster Car
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