Differant 91 92 tach issue
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Joined: Feb 2003
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From: chesapeake va
Car: 08 Sierra, 08 Silverado, 91 z28
Engine: 5.3, 4.3, 5.7
Transmission: autos
Differant 91 92 tach issue
my tach reads way way high like 7500 rpm at idle high> i swapped the gauge cluster, the second cluster did the same thing. any ideas?
Thread Starter
Supreme Member
Joined: Feb 2003
Posts: 1,473
Likes: 0
From: chesapeake va
Car: 08 Sierra, 08 Silverado, 91 z28
Engine: 5.3, 4.3, 5.7
Transmission: autos
Re: Differant 91 92 tach issue
That was my first thought, but the first cluster was true to the mileage and so is the second one. I never have had the second cluster in a running car, until today but the chance 2 clusters had the same issue I can't believe. First cluster was in the 91 l98 car second was in a 305 tbi car
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From: Mooresville NC
Car: LOWERED ♦ CRIMSON METALFLAKE
Engine: ► 400 KUBES ◄
Transmission: 765R4
Axle/Gears: EATON POSI 4.56
Whacky & Tachy
2 or more tachs of the same vintage can show similar erroneous readings due to the fact the parts which go defective age the same way.
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 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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How bout those too scared to drive without headlights in the daytime
and the ones that need headlights for a little rain
.
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 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!
◙◙◙◙◙◙◙◙◙◙◙◙◙◙◙
How bout those too scared to drive without headlights in the daytime
and the ones that need headlights for a little rain.
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