2002 3.8L Speedometer Problem
 

Hello everyone, I'm having a bit of an issue with my 2002 3.8L Camaro's speedometer. I have scoured the Internet everywhere for a similar problem in my year model, but have come up empty handed. So I figured where better to come for help than the Camaro forums here!

I recently got the car back from a family-friend mechanic who put a new engine in it (OEM) and only recently noticed this.

When I start driving my speedometer climbs gradually upward as it should. That is until I hit about the 40-50mph range. This is when my speedometer starts "bouncing" back and forth with a range of about 5mph of the true speed. It seems to exacerbate the problem when I accelerate harder. As far as I can tell, the car is running normally as it should and the "bouncing" of the needle seems to have no effect on anything else. All the rest of my gauges are operating normally as they should.

Have any of you experienced a similar problem before or possibly have any insight as to what might be going on here?

Any help you guys can provide will be GREATLY appreciated!

Thanks in advance!

The computer drives the speedometer depending on the output of the VSS. Could be a bad VSS, a bad speedometer, wiring problem, or even electrical interference.

Where is the VSS located? Is there any way I can test it to see if it is functioning properly?

i am having the same exact problem hows your volt gauge ive noticed my car only does it when my volts are real low from the lights ac and the turn signal its kinda funny it dances with the tick (bad battery the volts are always just above red but it starts great everytime )

I will check the volts out today on my way home and report back what I find.

On a slightly odd note, over the past few days of driving to work in the morning, it doesn't seem to do it. But, on my way home, it does. I don't know how the differences of ambient temperatures between night and day would have on it, that's just been my observation.

i havent noticed anything day or night but i have a vid ill post later right now im on my cell fone

Checked my voltage and everything is reading as it should with no fluctuation.

On my way back home tonight from class, I noticed that I wasn't experiencing my speedometer problem at all. It only seems to occur when I am on my way home from work which is usually around 3:00. I live in Houston, TX where it can get considerably hot during the day and cools off 15-20 degrees at night. With this in mind, I am wondering if the temperature during the heat of the day has anything to do with it?

The VSS sennsor is on the transmission tailshaft bhousing.