Low Coolant Sensor Schematic
Thread Starter
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
Low Coolant Sensor Schematic
I found this module in my dash right behind the fuse panel. It turned out to be the low coolant indicator module. The box was covered with sticky goo from being taped to the wiring harness and when I cleaned it up the part number that was rubber stamped on there got erased so I added the label.
The back side:
This is an interesting circuit. U1-E & U1-F are an oscillator that operates at about 5 KHz. The circuit filters this out and applies it to the transistor, which turns on the low coolant indicator lamp. When the low coolant sensor is submerged it basically shorts out the output of the oscillator and turns off the transistor, so the low coolant lamp goes out. The 160K resistor and 10uF capacitor put in a delay of a couple of seconds, which keeps the lamp from blinking rapidly when the coolant is sloshing around the sensor. I think it's interesting that the coolant is the return line to ground for the one wire sensor. None of the components have mysterious GM part numbers, so it should be easy to repair this module.
The back side:
This is an interesting circuit. U1-E & U1-F are an oscillator that operates at about 5 KHz. The circuit filters this out and applies it to the transistor, which turns on the low coolant indicator lamp. When the low coolant sensor is submerged it basically shorts out the output of the oscillator and turns off the transistor, so the low coolant lamp goes out. The 160K resistor and 10uF capacitor put in a delay of a couple of seconds, which keeps the lamp from blinking rapidly when the coolant is sloshing around the sensor. I think it's interesting that the coolant is the return line to ground for the one wire sensor. None of the components have mysterious GM part numbers, so it should be easy to repair this module.
Last edited by Cliff Harris; Dec 28, 2011 at 02:54 AM.
Thread Starter
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
That's cool. I like the color coding. Did you draw that?
I didn't calculate the time constant. I just guessed based on what I saw happening on the scope.
One thing I noticed: 100M is not a standard resistor value. They only go up to 20M.
I didn't calculate the time constant. I just guessed based on what I saw happening on the scope.
One thing I noticed: 100M is not a standard resistor value. They only go up to 20M.
Slingshot
Joined: Dec 2001
Posts: 3,817
Likes: 24
From: Charlotte NC
I don't know about the resistor value.
- 1986 Original Owner -
Joined: Apr 1999
Posts: 3,193
Likes: 138
From: North Yorkshire, England
Cruise-In I Veteran
Cruise-In II Veteran
Cruise-In III Veteran
Cruise-In IV Veteran
Cruise-In VII Veteran
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Grand Sport & Grand Sport X Launch Alongside All-New 535hp LS6 V8!
Michael S. Palmer
5 Reasons Bad Drivers Crash & 5 Ways to Avoid a Costly Mistake!
Joe Kucinski
7 Bolt-On Upgrades From Extreme Online Store to Level Up Your C6 Corvette
Pouria Savadkouei
How Likely Are These Five 2027 Corvette Rumors to Be True?
Brett Foote
9 Best Corvettes You Can Buy for Half Price (& 1 You Should NEVER Buy!)
Joe Kucinski
8 Very Best Corvettes of Amelia Island 2026
Joe Kucinski
Top 10 WORST Corvette Engineering Failures of All Time!
Joe Kucinski
10 Records the C8 Corvette Generation Has SMASHED (& 1 Glaring Failure)
Joe Kucinski
7 Wildest Corvette Concepts Ever Made
Brett Foote
Melting Slicks
Joined: Feb 2003
Posts: 2,634
Likes: 790
From: Saskatoon Sask.
Drifting
Joined: Feb 2008
Posts: 1,535
Likes: 177
From: NE Ohio
2024 C4 of the Year Finalist - Unmodified
OOPS post on wrong thread. LOL
Last edited by kenmohr; Apr 18, 2018 at 06:48 AM.
