Pull hood release, tach drops?

[MJ'sBlkBII]

This is interesting. I have been having an issue of my tach running 500 high at idle up to 1k high as rpms increase. I got home yesterday (truck driver) and fired it up and the tach was off as it was when I left it. I held the rpms to about 3k (per the tach) and then all of a sudden it corrected itself. Shut it down, came back to it a while later to run to the bank, and the tach was off again. Tried the throttle thing and it didn't work. I popped the hood and watched the rpms drop agin, this time only for a split second and then they went back up. Pulled on the bar that the hood release is mounted to and the rpms do the same dip/raise again.
Ground issue? Moving wires somewhere?
Funny thing is I'm sitting in my banks parking lot folded under the dash trying to figure out what is touching/moving. Needless to say it got some attention from other people. LOL Didn't find the cause of the issue yet though. Will be taing the dash apart at my earliest oportunity to check the wiring.

 

[Earl43P]

There is a ground on the radiator support.

I would disassemble and clean that up LONG before I went anywhere near the dash.

 

[MJ'sBlkBII]

It is dash related. The "bar" I am refering to is the cross member for the panel under the steering colomn. I had time to do the disassembly and the only way to get the needle to drop is by slight twisting of the cluster assembly. So, I am thinking that the either the gauge is going bad or maybe there is a bad connection for the gauge to the cluster housing since manipulating the plug/wiring has no effect. Pulling on the lower dash created the same effect of twisting the cluster assembly.
I am going to diassemble the cluster and see if that gives it a new contact. If that doesn't work, I will hit the local j/y and see if I can pick up a replacement.
Any ideas on where to find NEW gauges?

 

[MJ'sBlkBII]

Welp, got it apart and back together as far as putting the gauge in the housing and then putting the housing in the inplace to run the plug to it. N0 change, but have figured out that if I tap on the gauge just below the needle it will drop to where it is supposed to be. Tap pretty much anywhere else and it jumps back up. While it is possable the housing circuitry is bad, my money is still riding on a bad gauge.
Thinking I am going to reinstall the speedo cable and other harness, and run the truck to the j/y so I can grap a new one, simply pull out my old one, stick in the new and see if it works. This way if it doesn't work it's just a matter of pulling it off and going hunting again. A lot less work, only having to reasemble it all once.

 

[MJ'sBlkBII]

Figured out it was the guage that was bad. I screwed up the "circuit board" on the cluster housing and fried the grounds trying to get the housing out. I grabbed a replacement from both a 3.0 and 4.0 ranger (just in case). The 4.0 cluster didn't want to work (could be bad guages on this housing) but the 3.0 worked like a charm. Think the coolant temp guage is more off than my original, so I will try swapping them out and see what that does.
Tip: Pull the 2 bolts holding the steering colomn to the dash frame. This will drop the colomn and there by giving you all the room you could need to get to the connections on the cluster housing.