Electronics Need help wiring something up? Thinking of adding an electrical component to your car? Need help troubleshooting that wiring glitch?

Tach stuck at 8,000

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Old Mar 24, 2010 | 02:07 PM
  #1  
joee5's Avatar
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From: Central New Jersey
Car: 1986 Z28, 2006 Cadillac Escalade
Engine: 5.0 litre
Tach stuck at 8,000

any idea why or how to unstick? Trip also dont work. However speedometer works as it should. I have an 1986 Z28 Ima restoring myself and electronics got me befuddled. Thanking y'all in advance. Hopefully I inserted this in the correct spot.
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Old Mar 24, 2010 | 03:01 PM
  #2  
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From: Mooresville NC
Car: LOWERED ♦ CRIMSON METALFLAKE
Engine: ► 400 KUBES ◄
Transmission: 765R4
Axle/Gears: EATON POSI 4.56
Can you tell if it’s mechanically stuck, or, does it peg when you turn the ignition on?


Happy Racing!


“Just One Of Them Racin’ Deals”

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Old Mar 24, 2010 | 03:34 PM
  #3  
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From: Central New Jersey
Car: 1986 Z28, 2006 Cadillac Escalade
Engine: 5.0 litre
Re: Tach stuck at 8,000

oops, my bad. my polish kielbasa fingers hit 8 instead of 7. so my tach is stuck at 7000.
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Old Mar 24, 2010 | 03:34 PM
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From: Central New Jersey
Car: 1986 Z28, 2006 Cadillac Escalade
Engine: 5.0 litre
Re: Tach stuck at 8,000

stuck all the time
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Old Apr 3, 2011 | 12:48 PM
  #5  
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From: Willis, Tx
Car: 1986 Z28
Engine: 305 TPI
Transmission: 700R
Axle/Gears: Stock
Re: Tach stuck at 8,000

so does mine. I've read a bunch of articles about wrong readings but mine is at 7000 with car on or off and i took the faceplate off to manually move the needle and it falls to 0 and stays there and won't go anywhere in between. any help?
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Old Apr 4, 2011 | 04:55 PM
  #6  
NINÅ's Avatar
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From: Mooresville NC
Car: LOWERED ♦ CRIMSON METALFLAKE
Engine: ► 400 KUBES ◄
Transmission: 765R4
Axle/Gears: EATON POSI 4.56
High Revving Stuck Car

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!



I Don’t Mind Wreckin’ On The Track, No Paperwork To Fill Out

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Old Apr 8, 2011 | 09:57 AM
  #7  
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Re: High Revving Stuck Car

Originally Posted by NINÅ
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!

I Don’t Mind Wreckin’ On The Track, No Paperwork To Fill Out

.
I see this fix for alot of the Tach problems, does anyone have pictures of the process for this repair?
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Old Apr 8, 2011 | 10:04 AM
  #8  
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Re: High Revving Stuck Car

My tach was working with the headlight switch off, I pulled the cluster out to see if I could find a short since everytime I would pull the headlight switch on the tach would die and the right turn indicator would come on. I cleaned the contacts checked the electronic strip for connectivity, plugged it all back in and the results were the same, however now the tach rests @ about 4k and when the key is turned on it pegs the redline bar. Start the engine and no movement. Is there another connector somewhere on the main wire loom that could be acting up?
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