We went up to the Finger Lakes in NY for the 4th July week. While up there crusing around Seneka Lake, sampling wine, I noticed the tachometer was between 4000rpm and 5000rpm while I was shifting around 2nd and 3rd gears. The truck was only traveling between 25mph and 35mph at the time. When in 6th gear, crusing at 55mph to 65mph, it was odd to see the tach needle hang steady between 4000rpm and 5000rpm. The engine definately was not spinning at these 'indicated' rpms. No clutch slippage, truck has 28,000 miles on it. No towing at the time of this event either.

I should have heard the engine screaming at these 'indicated' rpms, but the engine sounded no louder than it normally would at these vehicle speeds. I pushed in the clutch, put it in neutral and coasted, and the rpms on the tach settled down around 2500rpm. I could clearly hear the engine was idling at its normal idle speed.

I pulled off to the shoulder, and killed the engine. The needle on the tach settled, and rested at the 1500rpm mark. It should've rested down near 0 as it always has. I started up the engine again, and let it idle, and the tach needle again showed roughly 2500rpm at idle. The engine was clearly idleing normally.

Since everything else was OK, we went on with our day. By the end of the day, with each successive stop, the tach needle would rest closer to 0 with the engine off. By sun up the next day, the tach needle was back where it should be when the engine was off, 0rpm, and the tach needle once again matched actual engine rpm.

Not sure what caused the problem. Could the CPU have been sending bogus info to the tach? Could the CPU have been getting bogus data from... ???

I have an appointment with my dealer tomorrow. Kinda sucks 'cause I really don't have a visual problem to show them, only a story. I'm doubting the CPU would've stored this event.

RustyFuryIII

 

Instrument panel?

Unless something was really wrong electronically with the PCM, as in the output to the tach was noisy (electronically noisy), there's no way the PCM would be thinking "I'm doing 2500RPM" when it's doing 800.

Either something in the instrument panel itself, or the tach - I have no idea how integrated the tach is into the instrument panel circuit board.

Check your grounds?

 

krewat,

Naw haven't checked the grounds yet. Just got back to VA, unpacked, and took the truck to wash it. The other reason I didn't think of grounds was the fact the truck is still kinda new. Do you think I should pop the instrument panel and take a look see? It appears to be working OK for now.

I won't have time to look at it until the coming weekend. I'm working nights for a while.

Enjoy,
RustyFuryIII

 

Looking at it won't help

Log it with Ford, have them check it. That way, if/when it finally goes, and your just out of warranty, they will/might fix it ...

Something says to me "there was a TSB for the instrument panel" but I don't remember the years.

 

Found it - https://www.ford-trucks.com/tsb/full...php?tsb=06-7-4

Built before 1/26/2006 ??

 

Not sure, I know I ordered it around the end of '05, or the first week of '06. Don't have it with me tonight, I'll check it out ASAP and get back to you. What I read from your link, sounds like what happened to me. We'll see.....

Enjoy,
RustyFuryIII

 

I was able to call my wife, she checked the tag inside the door jam. The build date is 1/06.

I was unable to get the truck to the dealership today. Will have to do that soon.

Enjoy,

RustyFuryIII