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Old 12-15-2008
seminaryranger's Avatar
Thread Starter
Join Date: Apr 2006
Location: Ganado, TX
Posts: 356
Erratic Tachometer (weird)

I'm having an issue with my tach lately.
Whenever idling in gear or in park, the tach reads unusually low. After a few seconds, it will eventually bottom out at the 0 peg and stay there. However, it may jump to ~500RPM and fall again to 0 shortly repeating this cycle as long as the engine remains idling.

The engine is not idling as low as the tach is reading. I have verified from my ScanGauge a normal RPM of ~800 in Park.

When the engine speed is raised above idle, the tach seems to function normally and read similar to the ScanGauge.

There are no CEL codes.

Any suggestions?
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Old 12-16-2008
wydopnthrtl's Avatar
iTrader: (2)
Join Date: Dec 2005
Location: SE, Mi
Posts: 2,342
Not good.. Since the PCM is seeing it accurately it's most likely the guage cluster.

On *other* engines, I've seen the tach jump because of loose wire on plug connections and because of bad ignition modules.

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Old 12-16-2008
Igobytwitch's Avatar
Join Date: Oct 2008
Location: Cocoa Beach, Florida
Posts: 504
Oh, i read it as "erotic tachometer" my bad
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Old 04-14-2010
Join Date: Mar 2010
Location: Lompoc, CA
Posts: 10
I'm having the same problem with my 01 ranger.. Did you get it fixed?
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Old 04-14-2010
Blhde's Avatar
Join Date: Oct 2005
Location: Northern IL
Posts: 2,804
My truck is doing the same thing, I have fixed it once.

There is a bad contact for the tach, its on the cluster where the connector plugs in. The thin copper has developed a bit of corrosion, probably form it being touched.
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