First off, I want to apologize, because I know this issue has probably been covered extensively, but I want to make sure my specific situation is taken into account and I'm not looking at a generic answer.

A couple of weeks ago, after driving almost an hour home on the highway, I looked at my gauges as I was approaching city limits and noticed that A) my speedometer wasn't working and B) when I stopped at stop lights, my temperature gauge would climb. While moving, it would slowly fall back down to about the halfway point (200 degrees). If I sat at a stop light long enough, it would nearly reach the red zone of the gauge, greater than 230 degrees. I had previously had this problem (about two years ago), and it was found to be one of the cooling fan relays. I assumed the gauge issues were unrelated, as the speedometer had gone out briefly a couple of months prior. I don't drive my car much, so I didn't take it in to the shop to have it check out until Monday of this week. I took it to Midas (the only place in the area, that I know of, that will do a free visual inspection) and was told that my car was, in fact, not overheating, but that my gauges were going out. At the same time, though, he told me that when the temperature was physically tested, it reached 235 degrees, which seems extensively high to me, considering the gauge only goes up to 260, and considering the normal running temperature for the past two years has been about 200 degrees or lower.

My question is: Since the temperature gauge is still moving, and is moving in relation to whether I am moving or sitting still, could it still be a gauge issue (which I have learned is a prevalent issue in many GM's of around this age)? The Midas guy assured me that I was okay to drive my car, other than not knowing if it was ACTUALLY overheating. I just want to make sure I am not going to do serious damage to my car, and I really don't want to take it to the dealer or somewhere that charges me $100 for 5 minutes of hooking it up to a machine, only to tell me it IS the gauges.

Any info or ideas are greatly appreciated.

 

My assumption is that there is air in the cooling system. Usually when it fluctuates with throttle it is a tell-tale sign.

 

Remove top hose at radiator fill with coolant replace hose run car repeat if necessary

 

This may be a long shot, but try pulling your EGR valve and cleaning it and the ports, they get carboned up and can cause the motor to excessively heat up.

 

What is the Mileage of your cluster/Car?

I will say I don't think that it is any thing related to temp. I think your gauges are going out or are out.

if you don't drive it much there is a few things you could do. 1 could take cluster out and look over the back of the connector area over the solder Joints. Would love to see some pictures if you were to do this your self, IF you have a Good Soldering Iron, Weller, Hakko, or JBC would fit the Good iron field. I would Resolder the Connector back on the the Clusters PCB. I guess if you have some type of Hot air system and knew how to use it well enough, You might be able to get away with doing a fast reflow of the connector.

Also There is another thing you could do, Make note of your Mileage and if over 100k miles You could go to a Local Pick-N-Pull or U Pull it yard and buy a replacement. There are some people that even offer them on Ebay. Some say VIN and Mileage would be needed. I would assume they program it for your car. I know there was someone that would Re Program them in the past however they don't do anything like that anymore and I don't know anyone to refer anyone to.

I have a Couple of Working Clusters for Impala LS Normal. Has 175k miles working from my 00 Impala and I have an Extra 02 SS 6 Gauge Monte Carlo cluster working with 193k that I bought for my MC as backup if needed.

Also could be other issues other then Cluster, Maybe issue with Grounding and or BCM could be having issues over your Data lines between the BCM and Cluster.

James