High Tach reading

[Hawkeye]

On startup my Tach goes to roughly 2500 rpm. Not the actual rpm of the motor. The rpm will go higher, but not any lower until I shutoff the engine. I have not looked at anything yet.
Any suggestions?

 

[RobWigglezz]

Sorry I misunderstood your question and deleted my first post.

You're saying the tach jumps right to 2500 and never goes lower? The gages have posts that push into metal clips which make a connection to the flexible circuit board on the back of the cluster. They can loosen up and cause weird stuff to happen.

This will sound a little caveman, but a few taps on the dash could make the needle move if I they're loose. My tach was erratic and tapping on the dash would make it move.

On startup my Tach goes to roughly 2500 rpm. Not the actual rpm of the motor. The rpm will go higher, but not any lower until I shutoff the engine. I have not looked at anything yet.
Any suggestions?

 

[Hawkeye]

Sorry I misunderstood your question and deleted my first post.

You're saying the tach jumps right to 2500 and never goes lower? The gages have posts that push into metal clips which make a connection to the flexible circuit board on the back of the cluster. They can loosen up and cause weird stuff to happen.

This will sound a little caveman, but a few taps on the dash could make the needle move if I they're loose. My tach was erratic and tapping on the dash would make it move.

Sorry, my post was a little confusing. The truck runs fine. It's just the tach goes to 2500 on startup and won't go lower until shutoff. I tried tapping on the dash panel/ gauge with no fluctuation. One thing I read on a Google search, mentioned the ignition coil or voltage regulator. Is that a possibility? Or is it most likely something in the instrument panel?

 

[Hawkeye]

Update to my post. I ohm'd out the ignition coil, primary and secondary coils. When I first checked the primary coil it was bouncing between 7.5 - 8.0 ohms
The secondary coils all were roughly 11.5 k ohms. According to the Haynes manual, the primary coil should be less than 5 ohms and secondary coils 13 - 15 k ohms.
So I thought I found my problem. I went to Advance auto parts and got a new ignition coil. Unfortunately I'm getting the same results with new coil
The new coil primary reads less than 5 ohms, but the secondary coils all reading roughly 12.5 k ohms
I rechecked my original ignition coil and the primary now reads less than 5 ohms
This post should really be in the electrical/instruments forum, but I couldn't figure out how to move it

 

[85_Ranger4x4]

Has the tach ever read close to right while you have had the truck?

 

[Hawkeye]

Never had any issues until day before yesterday