High idle problem, unable to solve. (Page 4/4)
Vintage-Nut AUG 18, 08:44 PM

quote
Originally posted by Patrick
It's not a "switch". The coolant temperature sender is for the temperature gauge.



Both of you are 'right'.....

Sensor/Sender, Coolant Temperature (GM 25036809)

Two Circuits in One:
Variable Resistor for the gauge
Switch for the coolant temperature warning light (bulb)

Edit: This unit is for the temperature gauge and warning light ONLY

IF you're SURE that you don't have any vacuum leaks, and still have 'High Idle Problems'

Replace the engine coolant temperature sensor for the ECM (GM 25036979 for V6)


quote
Originally posted by Jeffdylanproctor
My car was having a very similar issue and it turned out to be the Coolant Temperature Sensor that was causing the high idle, as evidently the ECM wants the idle high till it reads a certain temp. These cars have two temp sensors, one that goes to the gauge, and one that goes to the ECM.

The one that goes to the ECM and causes the Idle issue is up right under the Thermostat housing. it is a little tricky to find and see, but it is very easy to remove. The factory plugs tend to have issues as well, and you can easily buy a plug with the sensor.

The high idle was driving me up a wall and this fixed it. Sounds crazy, but this sensor can cause a high idle.

[This message has been edited by Vintage-Nut (edited 08-19-2023).]

Patrick AUG 18, 08:58 PM

quote
Originally posted by Vintage-Nut:

Both of you are 'right'...



Not really. The OP expressed an interest in replacing the coolant temperature sensor for the ECU, not the sender for the temperature gauge. There is no "switch" whatsoever in the coolant temperature sensor for the ECU.

I still strongly suggest that the OP find out what's going on with his engine by getting a reading of all the sensors first before randomly replacing them.

[This message has been edited by Patrick (edited 08-18-2023).]

cyrus88 AUG 19, 12:51 AM

quote
Originally posted by Patrick:

. . . before randomly replacing them.




Where's the fun in that? Shotgun approach is the best way to keep one busy.😁
Vintage-Nut AUG 19, 10:03 AM
As Fierogt28 said "I would recommend replacing all sensors for peace of mind"

I did too!
ketstang OCT 18, 05:00 PM
Well, wanted to get back to everyone on my high idle problem. After several suggestions to replace the coolant temperature sensor for the ECU, I did and stated that it didn't seem to work. I have now driven it 100 miles and it is now idling at about 1500rpm at startup but slowly idles down to 800rpm. I am very satisfied with this and want to thank all of the people who have helped me along the way!

I have a newly found problem, but that's for a new thread. It's unbelievable (to me anyway).