one_bad_55

I have a 2007 and about a year ago our tach started acting funny. The needle moves with the RPMs but it will not reset to 0 when you shut the car off. Now when the car is turned on my tach shows about 5000 RPM at idle and goes up from there until the needle is off the range of numbers until it is almost pointing straight down. It does move as I speed up or slow down but it is obviously not right.

I can sit there and turn the car on and off about 20 times (without starting it) and it will eventually go back to 0 but once I start it the tach never goes back to zero when I turn it off.

Any ideas?

whopper

I haven't heard of that one before. Have you had any other issues recently or about the time the tach started acting weird?

You can try disconnecting the battery (negative post only for safety reasons) for about a half hour - it might reset things, but no guarantees, but it's worth a try.

Oldblue

X2, the old battery lobotomy has worked wonders before!

Then check the grounds

https://www.chevyhhr.net/forums/how-...cations-56504/

one_bad_55

I am going to be doing some maintenance on it in the next couple of weeks and that might be a good time to try the battery trick. I was going to put in some new plugs, K&N filter, headlight bulbs, and wipers so that would be a good time to disconnect the battery.


I will give it a try. Thanks

Oldblue

Please remember, AC Delco 41-103 iridium plugs .

one_bad_55

I picked up a set of NGK Laser Iridium plugs at the tune of about 8.50 a piece. These are supposed to be the best you can buy. I sure hope these are good enough.

donbrew

This is the etirety of what the Shop Manual has to say:

one_bad_55

Yeah, no, it never goes to 0 RPM. I took the car out today and it is no longer even moving and it is pretty much stuck pointing straight down. I am not sure if the battery thing will even work. If I physically move the needle by hand will it damage the tach? I suppose no more than it already is. Would that possibly indicate a short on the wire that goes to the tach?

Where does the wiring harness go from the gauges? All the other gauges, lights, and displays work on the dash so maybe it is just the one wire controlling the tach.

donbrew

That's what "serial data" means.

firemangeorge

Hmm. Almost sounds like the tach needle is loose on the shaft. Don't be surprised if it just falls off.