I am having an odd issue. The temperature gauge in the dash goes over N at about 183* F and pegs all the way to red when the car gets over approximately 188* F. My temp numbers are according to my Ultra Gauge I have mounted on the dash that I use to monitor temperature. I have never had any kind of red idiot light go on but it is quite disconcerting to be sitting in traffic and the the temp gauge in the dash climb to the red zone while my ECU is telling my Ultra Gauge everything is in normal operating range (the Ultra Gauge plugs into the OBDII connection).

I replaced the sender unit at the thermostat. Also put in a lower temp 170* F thermostat. Since I live in Florida did not think it was a big deal to go lower. Car never gets above 195*-200* even in 100* blazing Florida sun and in traffic with the a/c on. Normally runs in the 180*F-190*F range unless in traffic with the a/c on.

Could this be a ground issue somewhere? Don't even know where to start looking.

Any help on solving this would be greatly appreciated. Thanks!

 

I have had a broken drive belt on a couple of occasions, and noticed that the water temperature gauge pegged pretty much as soon as the ignition warning light came on. Whilst I appreciate that the temperature will go up quickly without the water pump turning, I was surprised to see it peg so quickly at tickover, so much so that I began to wonder whether the gauge is an "idiot gauge" like the oil pressure gauge, and any reading over normal temperature limit causes it to peg? It certainly catches your eye and gets you to switch off quickly!
The reason I ask the question is that if it is an idiot gauge, your temperature may have only strayed a couple of degrees above normal, and yet the gauge would peg. Have you flushed your cooling system, and checked your radiator for external blockages to the airflow, which might explain a slightly higher temperature?

 

The temp gauge is indeed a idiot light, but it should not move off half scale until the temp reaches 230 or so.

 

Right, an idiot gauge.

I 'suspect' a electronics problem in the cluster.

Cheers
DD

 

I will pursue the problem at the cluster. In addition, the fuel gauge is pegged at full regardless of how much fuel is in the tank.

 

The fuel gauge sender is a common failure issue. It can be replaced easily by removing the trunk liner at the back of the tank, but the tank should be less than 1/4 full. Hard to tell without the gauge working.

 

If your fuel gauge is playing up too, I would start at the cluster. It is very easy to remove and dismantle, and you wont get covered in petrol!

 

I already replaced the the fuel sender unit thinking that was the issue but it didn't solve the problem. I will start at the cluster. Thanks. ARE THERE ANY GOOD INSTRUCTION GUIDES ON REMOVING THE INSTRUMENT CLUSTER OUT THERE?