Yesterday when driving I noticed my temp gauge acting really funny. It would be showing normal temp (mid gauge) and all of a sudden shoot down to less than a quarter on the gauge. Sometimes it would alternate back and fourth from these two positions in rapid sucession.

I know that I have a coolant leak between the housing in the area where the thermostat goes in. It's not a serious leak and I topped the coolant off during the weekend so it shouldn't be low. I replaced the thermostat around a year or two ago and noticed the leak a month ago, it think it's just a matter of creating a better seal (going to use RTV black this time).

What do you think is causing this odd behavior in the temp gauge and is it bad for me to drive like that? The fast movement makes me think that it's some kind of electrical short. Perhaps a sender or bad connection?

 

I had the same problem in my sons explorer. I replaced the thermostat and still have the same problem. The shop that fixed it told me that it is most likley the sender.
I have been ridijng likr this 4 5 mounts now with no problem. The gage goes up and down whild I'm driving.

KG

 

I replaced mine with an aftermarket one..I didnt like the jumping around..plus the whole guage and sender was less than just the oem sender.

 

did this fix the problem?

 

works really good....

 

It's come to my attention that the stock toyota sender may be "dampened" in some way so it displays a normal temp all the time, unless you get really out of range.

To debug your problem, you need to check the resistance value on the sender while it's jumping around.. you could rig it up with a single wire if you've got a ohmmeter (or volt meter) in the cab.

Determine if the sender is behaving... Alternately, pull the sender out, heat it with hot water at various intervales and check the resistance.

It could be your thermostat, as mentioned.. but I doubt it.. Could be a loose connection too, most likely at the sender.

1988 Toyota 4Runner 22RTE (build in progress)

 

Interesting, I'll have a look at that area this weekend if it's not raining too hard here in VA. Thanks for the input, I thought it might be an electrical/sender related problem. I just wanted to make sure other people thought so too before I spent half the day scratching my head looking around under the hood.

 

I am having a similar problem on my 89 4runner V6. When I first start the truck, the gauge is at 1/2 gauge....that would be impossible since the truck is COLD!! When I drive, it doesn't move anywhere. However, after some driving time, it starts to creep up to 3/4 gauge.

I tried unplugging the wire from the sensor, and the gauge doesn't move at all (IE doesn't go back down to zero, like it should....shouldn't it??)

could this be a gauge itself problem? Help anyone??

 

DeathCougar,
I have the same truck with the same problem. Did you ever fix it? What was the deal?

 

same prob here too. and my buddies 87 4runner. do you guys have sr5 guages as well? my old deluxe plain guage worked like you would expect one to....no temp when cold and gradually rise to temp. i don't understand why they would make two different type guages, as far as the dampened an the non sr5. i have read that they have dampened set up as well, but no definitive explanation. ??????

 

This is a poor connector at the gauge sender. Its a blade type.