temp gage went nuts

[Austin idi 7.3]

so to do i was driving my truck and parked it my shop and went in to spend time with wife then we go in my truck after it was sitting about 4hrs and the temp gage went straight to overheat an the engen lit cam on but the truck was cold idk what happened

 

[franklin2]

Check the wiring on the two sensors on the front driver's side head. Make sure it's not rubbed through and touching the block. If the wiring looks ok, then unplug the sensor on the front outer corner and see if that makes it quit.

 

[MIDNIGHT RIDER]

Although it hasn't done this in many years, the gauges in my 1985 used to go haywire and scare me to death about twice a year.

The first thing I would notice was the temperature gauge all the way past HOT.

After the initial heart failure, I would then see that all the gauges had went all the way to the right.

Quite by accident, I found that a few light taps on the plastic window just in front of the speedometer would bring things back to normal.

I never did actually find why this would happen.

Whatever, it must have went into remission, as it hasn't done it in a long time.

 

[smolkin]

If all the gauges go screwy at once, it can also be the IVR (inst. voltage regulator), the little metal box at the back of the instrument cluster. Stupidly expensive from dealer, just go to a junkyard and grab a couple.

 

[franklin2]

If all the gauges go screwy at once, it can also be the IVR (inst. voltage regulator), the little metal box at the back of the instrument cluster. Stupidly expensive from dealer, just go to a junkyard and grab a couple.

Just for your info, the 80-86 cluster has the IVR, the 87-up does not. I don't really know what year truck he has though.

 

[Agnem]

so to do i was driving my truck and parked it my shop and went in to spend time with wife then we go in my truck after it was sitting about 4hrs and the temp gage went straight to overheat an the engen lit cam on but the truck was cold idk what happened

YOu need to add a signiture so folks know what year truck you have. Two possibilities depending...

Your IVR is stuck, and is overvoltaging all your gauges. The temp gauge is the most reactive, but you may notice your fuel is too full, and your oil presure might be hihg.

Or...

Your overtemp switch has malfunctioned, or is shorted, or there is a wiring short.

Since your name has 7.3 in it, I'm going to guess it is the later, since you wouldn't have a truck older than 87.

 

[Austin idi 7.3]

Just for your info, the 80-86 cluster has the IVR, the 87-up does not. I don't really know what year truck he has though.

1991

 

[WrickM]

when my truck did this it was the second (high temp) coolant temp sensor going bad. The one on the head (i think) rather than right there on the top/front of the engine. i switched out the sensor and had no more issues.

 

[Austin idi 7.3]

Check the wiring on the two sensors on the front driver's side head. Make sure it's not rubbed through and touching the block. If the wiring looks ok, then unplug the sensor on the front outer corner and see if that makes it quit.

so i check the wireing and it was ok then i unpluge the high temp sensor and the gage shot back to cold so does this mean the sensor is bad and should i replace both sensors???

 

[WrickM]

i just replaced the one, and everything has been fine.

 

[franklin2]

so i check the wireing and it was ok then i unpluge the high temp sensor and the gage shot back to cold so does this mean the sensor is bad and should i replace both sensors???

It sure does look like that one sensor is bad. If you want to try it, just leave the wire off and drive the truck and see if the temp gauge acts normal. The other sensor is what runs the gauge, so if it's good the guage should read like it always did.

The one that looks like it's broke just pegs the gauge and turns the engine light on when you get above approx 230 degrees.

 

[Austin idi 7.3]

It sure does look like that one sensor is bad. If you want to try it, just leave the wire off and drive the truck and see if the temp gauge acts normal. The other sensor is what runs the gauge, so if it's good the guage should read like it always did.

The one that looks like it's broke just pegs the gauge and turns the engine light on when you get above approx 230 degrees.

ok thanks just one more ? i wen to my local napa and they told me both sensors where the same so i got one witch cost about 10.00 does this sound right?? tha both sensores are the same

 

[WrickM]

yup