temp gauge not working?

[Warduke]

Im not sure if its a thermostat or a sensor but the temp gauge doesnt move past the A on NORMAL no matter how long the car has been on, sometimes it goes a little higher but not past the M. I would say its only about 1/4" pasl the cold mark. Anyone have this? Once in a while if the car is hot and idling the temp gauge goes higher but thats only once in a while and doesnt stay there long especially once I start driving.

 

[Team Dave]

My SHO does the same thing.. Then I noticed every time I start the car, the fan comes on. It makes sense because sometimes when I'm stopped for a while, it goes to about halfway (where it should be), and sitting at a stop is usually when the high speed fan is most used.

 

[Eric VerValin]

Yeah man, mine almost never gets past the A either. I even verified the temp with an infared thermometer. A lot of people have said they have a broader 'sweep' from hot to cold, (thermostat open / closed) than I do, but I've never had any problems.

If there was an issue I would think it would be with the sensor located just to the left of the thermostat housing. Or possibly the little push pin connector is corroded, soemthing along those lines.

 

[Storm-Chaser]

It actually sounds like the gauge is working fine. Unless you have some reason to suspect overheating, operating in the 30-to-40-percent-of-scale (between "A" and "M") is typical for a cooling system in peak operating condition.

There are a number of threads/posts on this, using the search-term "temp guage or temperature gauge. Spending a few hours reading through the posts will reinforce the above, as well as saving you much more time and money chasing a problem that probably doesn't exist.


As far as trying to tie coolant temperature to the TEMP gauge reading (if you don't have a mechanical water temp gauge), AutoZone has started carrying an inexpensive infrared thermometer ($19.99). It has a temperature range of -31°F to +689°F . . . .

This is a new item, it's made in China, and there is no information on the product packaging nor their in-store database as to the accuracy of the thermometer. But it would allow you to at least tie temperature changes to changes on the TEMP gauge (or lack thereof).

OEM Infrared Thermometer - $19.99

AutoZone part number - 25245

AutoZone SKU number - 951642

Warranty - 90 Days
​

 

[Warduke]

thanks everyone,i was afraid there was something wrong like the thermostat being stuck open. The engine does get hot but I dont think it is overly hot. Ill go for that $20 infrared therm. Im sure it will have other uses as well.

 

[itwonder]

The thermostat could be stuck open, or the wrong thermostat is installed....Possibly somebody put a 180 degree in instead of the 192 degree, or it could be nothing at all. Does it take a long time to warm up? Also check to make sure the electric cooling fans are not running all of the time. Around the M is about normal for typical driving. In hot weather at idle it should go up past that to a point where the cooling fans will kick in, and then go back down. This prior post from Paul gives more detail:

The total range of movement depends mainly on your t-stat rating. The total gage NORMAL range is ~160F to ~230F. The low speed fan(s) come on at 215F, off at 210F.

So if you have a 180F t-stat instead of a 192F t-stat this will add 12F to the sweep.

If you are moving and the fans don't need to be on then the gage will read lower. If in traffic and the fans are controlling the temp then it will be considerably higher.

From the manual...............


The cooling fan is controlled during vehicle operation by the Constant Control Relay Module (CCRM) 12B577 and Powertrain Control Module (PCM) 12A650 which will energize the cooling fan under the following conditions:

Cooling fan is turned on for the 3.0L SHO and on at low speed for 3.0L, 3.2L SHO and 3.8L if:

a. Engine temperature is higher than normal. (Fan starts running at 102°C (215°F) and stops running at 99°C (210°F).

b. A/C is on and vehicle speed does not provide enough natural airflow. (Fan starts running at speeds at or below 69 km/h (43 mph) and stops running at 77 km/h (48 mph).

On 3.0L and 3.2L SHO engines with ATX, low speed cooling fan motor operation is achieved by using a dropping resistor in series with the motor/motors.

The 3.8L uses a dual winding fan motor in which low speed motor operation is achieved through the low speed motor winding circuit (no dropping resistor).

Normal operation and cycling of the engine cooling fan will cause the temperature gauge indicator to read between the mid-point and upper portion of the temperature gauge scale. The slightly higher indicator reading will return to mid-point when fan operation begins.

Cooling fan will run at high speed if:

a. Engine temperature is higher than desirable and fan has been operating at low speed. Fan starts running at high speed at 110°C (230°F) and stops running at 107°C (224°F).

 

[Storm-Chaser]

Read the numerous prior threads. The range that Warduke is describing is the typical range reported by most.

 

[SHOZ123]

If you want to test the gage.

A 74 ohm resistor between the sender connector and ground should make the gage read at the C mark.

A 10 ohm resistor between the sender connector and ground should make the gage read at the H mark.