My temp sensor is malfunctioning again (it happened at URE in April). This leads me to think that it could be the temp sensor again or could it be the gauge? anyone know what to do?


Thanks Collin

 

Which sensor - the two wire one that drives the ECU, or the single wire one that drives the guage? Who do ya trust???

Let me show you what a scanner can tell you:

First photo - 163 degrees, warming up

Next - 180 degrees

Next - 192 degrees

Next - 199 degrees

So you can see that big change in temp can make little change on the guage. If you don't have, or can't use a scanner for data (not equipped), you can use an IR thermometer. See next post.

 

An IR thermometer can make readings. But it can also be fooled. It is not measuring just the spot of the laser dot. The "beam" spreads out like a flashlight.

Here's a photo of the alternator, too hot to touch; and the radiator just after the top hose enters. The top hose itself read 10 degrees cooler, the rubber acts like insulation, compared to the brass radiator.

I would like to make two points:

1. You can get strange readings depending on the measuring device used.

2. If your guage is deviating from the normal range that you have enjoyed for the last several months, there is the possibility that the truck is overheating. You should check by several tests and stop driving the truck in case the guage is right, and you are frying the engine.

What kind of guage readings are you getting?

 

The sensor with the square yellow/orange top plug is the coolant sensor for the ECU, has two wires. The guage sensor is to the left of the coolant sensor, and has a single wire. The guage sensor looks like a brass bolt when you remove it, will read some value of resistance to ground.

 

I'll go take a look under the hood and report back. I lost the old thread i had started.

 

IR thermometer is my #1 most used tool. Excellent at finding troubled spots and identifying areas of concern.

 

Occam razor never fails. Turned out to be a cruddy sensor... Thanks for all the help!

Oh one more thing, I was driving home today and moticed that my "BRAKE" light was randomly turning on and off. I was driving on a dirt road and the Ebrake was off. Nothing to worry about, eh?

 

Check your bake fluid level, if it is low it will set off the brake light on the dash.
If it is almost low driving on a bumpy road or turning a tight corner will also set it off.

 

I'll check that out tomorrow afternoon, and report back