EQUIPPRO

My tach has been very sporatic lately. Sometimes it shows idle correctly at 750rpms. Next time I start the truck it shows idle at 300 rpms. Next start it may show idle at 400r pms. The idle is not off as I can tell by just the sound of the engine and the feel. If i rev the engine the tach needle jumps up a little bit. What causes the tachometer to be off????

A.D.

I also would like to know. Mine makes a whinning sound above 1500rpm when it is cold. I was under the impression it was electronic and no moving parts except needle??? I cant help with your issue, but your fix may be mine also. Mine reads correct, but there is something a miss.

critser660

I also have the crazy tach sickness. My guage says one rpm however my PDA says the correct rpm, so my guess is a short in the plug or in the line somewhere.

dale29

I have noticed it happening intermittently (sp?) it started about a month or so ago (around 93k mi) it doesn't seem to affect anything, mine is auto so I don't have much use for the tach anyway.
It would be nice to know if I just need to clean some sending unit or something.

EQUIPPRO

First I thought it may be the Smarty. So I removed the Smarty and put back to stock. Still getting eratick readings on the tach. It went past 3800 rpms on a hard take off. But I know the engine was not maxing out, just a false reading from the tach. Yesterday it was cold outside and at start up it showed the truck idleing at 200 rpms, but again the truck was running at normal by the sound, at 750rpms at idle. Is there a sensor that is bad or do I need to clean something, I don't get it. The very next start it was showing idle at 750rpms???????

rock crawler

Mine has been doing the same thing for quite a while. Some days the needle sits on the other side of the post (all the way around) and it shows 0 while driving then swings to 5k and back. Do a search and you will find that this is a fairly common problem with the 06 models. There are a few guys that have had to have the tach assembly replaced at the dealer. Some have been fixed with a flash but it seems to go back to doing the same thing after a while. I took mine in this week and they took about an hour checking it out and they said the flash was current and that they could not find what was wrong. They said I had to leave the truck so they could disassemble the dash to check out the tach unit. They said the charge would be around $400. If they found that the problem was with the tach unit then I would not be charged. If the problem was caused by something I did to the truck (accessories) then I would have to pay. I think that is fair, but I know that it has nothing to do with my mods because it was messed up before I put any mods on. And the fact that there are so many of these going bad they have to know that this is a common problem.

sid325

I have a friend having the same issue. Maybe you guys can help:

My 06 tach is all over the place. It started out as a bad instrument cluster which a dealer replaced under warranty while i was out of town at the inlaws. It first was every gauge would cut in and out as if it was a loose connection.

Now just the tach is jumping all over the place. During normal acceleration it will hover around 3-400 rpm's then once the actual RPM's get somewhere near 2K it the tach will jump way up to 3-4K. A couple times it wrapped all the way around to the bottom of the peg.

Every once and a while it will work normally. FWIW the ECM is seeing the real RPM's because when i use the edge A2 through the OBD2 port it reads normally.

I hate to go back to the dealer because every time i go in there something gets screwed up. Ive checked grounds and all seems well. I don't have any after market stereo stuff and it does the same thing w or w/out the edge plugged in.

Any body see this b4 or have any info?

Moneywoes

Its interesting that all these trucks with tach problems are 06's. My 06 had this same thing going on. Tach reading would jump around at idle between 300-750 rpm with no change in actual engine RPM or engine sound. Luckily at the time my truck only had 24320 miles on it and the bad instrument cluster was replaced under warranty at no charge to me. The dealer did have the truck for two days though as the new cluster had to come from STAR and be programmed for the odometer reading of the old cluster.

BigDiesels

My 06 has the same problems with the tach as well. Diagnosed as bad instrument cluster (just after basic warranty expired). It hasn't affected any other gauges yet, so I haven't replaced the cluster. Truck runs fine as it is.

zuki_dan

My truck has the tach jumping around at idle and cruise below 2k rpm. It has to be just the gauge because it doesn't pop any codes. I've been driving mine this way for close to a year. The next time I take it in for the steering TSB I'm going to have them check out the tach.

EQUIPPRO

I am way out of warranty at 151k miles. I would expect that a whole new instrument cluster would be a fortune form the dealer. Anyone know of a way to make sure the tach is bad or check where it reads on the engine??

A.D.

Can the instrument cluster be changed as a diy, or does it have to be programed? Not a fan of local dealer.