09/01/11

1. What is the coolant temperature should be when the gauge needle pointing to the middle of the scale?

2. What is the coolant temperature should be from the middle to red mark at the end of the scale?

3. What is the coolant temperature after the red mark at the end of the scale?

I can find out by grounding the coolant fan switch connecter wire to prevent the fan from coming on. Put a thermostat in the radiator, and run the engine {and getting to a safe temperature}. But my gauge is bad. Therefore I cannot do that to find out. Appreciate any input. Thanks.

 

There is no data available for the info you want.

Typically the engine coolant runs at around 185F = gauge in the center.

The fans should come on when the coolant reaches around 199F. If the T-stat is working the gauge still stays in the center.

The only time the gauge would move up is if T-stat can no longer compensate for the coolant temp. The T-stat is fully open but the coolant is too hot.

Have you checked the coolant temp sensor for the gauge? Most times the sensor is bad.

For Denso brand should be approx 226 ohm @ 122F, 26.4 @ 239F
For Yazaki brand should be approx 152.7 ohm @ 140F, 26.4 @ 239F

If you have access to the dash temp gauge wiring there are a few ohm reading tests you can conduct.

 

thanks!this is very helpful!!!

do you have a guide for the temperature gauge??

 

09/02/11
Thank you Toyomoho for your respond. I think I have a bad gauge. I disconnected the gauge sender wire. The gauge drop down but stuck above cold at 1/4 of the scale. I grounded the gauge wire with a test light. The gauge went up to the red, then dropped back 1/2 an inch. When I removed the ground, the gauge did not move down. It hung up for a while then went down.

I removed the instrument cluster. I checked the gauge resistance. A-B 54 ohm, A-C 147 ohm, B-C 201 ohm. I followed B on the printed circuit to the wiring harness connector. This goes to the gauge sender. with an ohmmeter I measured from B on the harness connector to the gauge sender connector (disconnected), the reading is 0 ohm (continuity). Then from B on the harness connector to ground, the reading is infinity (no short to ground).
Did same thing, followed C on the printed circuit to harness connector. This goes to ground. with an ohmmeter I measured from C on the harness connector to ground, and read 0 ohm. So, nothing wrong with the gauge resistance or the wires. Must be mechanical problem with the gauge. I am going to buy used instr cluster.
Hi full house. are you asking me or Toyomoho?,
I do have a pdf file showing how to check the gauge resistance, and its value. I think one of the values it is giving is wrong.

 

The ohm readings appear OK.

You can try to simulate the coolant temp sensor by replacing it with known high/low resistors having the ohm values provided in a previous post. Perhaps RadioShack has something or a potentiometer. This way you can test the gauge response.