Archived Are any of these symptoms related?

[KenChristensen]

1. Tach reading below 500 when idling. Then jumping up to the normal 750 or so.

2. Upon cold start up, the engine goes straight to high idle. My '03 would wait for a bit.



'06 Mega cab 2500 4X4

 

[Whiskey]

Mine does the same thing,also when you are ideling in cool/cold weather it will idle up to 1000 rpm, this helps stop cly wash down!!

whiskey

 

[KenChristensen]

The engine stays at the same RPM's, only the tach itself moves

 

[Missouri Mule]

Your tach is messed up or loose connector/wires.