77 Coolant Temp sensor specs
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5th Wheeling
Joined: Apr 2021
Posts: 49
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77 Coolant Temp sensor specs
Hello again.
Would anyone know the specs for the coolant sensor for a 77 Ford F250 with 400?
I installed a new coolant sensor and 'it' still doesn't work.
Here are the steps I've taken thus far:
Connect wire to new sensor - no workie (not expected)
Ground wire to verify gauge works - Gauge works!
Test continuity b/t sensor body and ground - Continuity (expected)
Test continuity b/t sensor body and stud - no Continuity (expected)
Test resistance b/t sensor body and stud at ambient (ambient being 90 deg F, b/c I'm working outside) - No ohms --> is that right?
Engine at op. temp, test resistance b/t sensor body and stud - No ohms --> is that right?
What am I missing here? Am I testing this correctly?
thanks!
Would anyone know the specs for the coolant sensor for a 77 Ford F250 with 400?
I installed a new coolant sensor and 'it' still doesn't work.
Here are the steps I've taken thus far:
Connect wire to new sensor - no workie (not expected)
Ground wire to verify gauge works - Gauge works!
Test continuity b/t sensor body and ground - Continuity (expected)
Test continuity b/t sensor body and stud - no Continuity (expected)
Test resistance b/t sensor body and stud at ambient (ambient being 90 deg F, b/c I'm working outside) - No ohms --> is that right?
Engine at op. temp, test resistance b/t sensor body and stud - No ohms --> is that right?
What am I missing here? Am I testing this correctly?
thanks!
Last edited by icechickenx; Jun 27, 2022 at 11:02 AM. Reason: correct spelling
Lead Driver
Joined: Jul 2017
Posts: 9,603
Likes: 1,174
From: San Jose, CA
It sounds like you’re doing it correctly.
You’re probably seeing a defective new part just like we talk about all the time here.
The correct resistance readings for our your vehicle should be 73 ohms called and 10 ohms pegged full hot.
I think the actual precise readings are some variation of the 73 to 10 range, but getting down to the 10th of an ohm isn’t really going to change anything.
Sounds like you need to take your multimeter to the parts store and check each one out of the box.
You’re probably seeing a defective new part just like we talk about all the time here.
The correct resistance readings for our your vehicle should be 73 ohms called and 10 ohms pegged full hot.
I think the actual precise readings are some variation of the 73 to 10 range, but getting down to the 10th of an ohm isn’t really going to change anything.
Sounds like you need to take your multimeter to the parts store and check each one out of the box.
Lead Driver
Joined: Jul 2017
Posts: 9,603
Likes: 1,174
From: San Jose, CA
Yes. They’re supposed to be within that minimum and maximum range.
As far as I know it should never read zero at any temperature. Zero is just like you grounding the wire and pegging the needle.
As far as I know it should never read zero at any temperature. Zero is just like you grounding the wire and pegging the needle.
Lead Driver
Joined: Jul 2017
Posts: 9,603
Likes: 1,174
From: San Jose, CA
Very possible. First one I ever bought back in the 70s was for a light instead of a gauge. Had to go back and get another one.
if that’s the case here it would read infinite and once you heat it up to what? Maybe 230°? It would read zero. Just open and closed…
if that’s the case here it would read infinite and once you heat it up to what? Maybe 230°? It would read zero. Just open and closed…
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Laughing Gas
Joined: May 2021
Posts: 1,163
Likes: 360
From: Anderson, California
I just installed a new gauge and sensor from O'Reillys for my amc.
I found there to be differences in ohm's reading hot and cold while field testing different sensor's in the kitchen with my wife's candy thermometer, and a pan of water on her stove.
Before installing the new gauge, I wired it up in the kitchen and put it thru it's paces, and for a $35 gauge, I was happy.
If I am remembering correctly, at ambient room temp, say '86-degrees, you should be getting a reading of either high or low.
I never had any luck getting my old gauge to read properly with whatever sensor I used, so my cluster gauge must have some sort of continuity issue with connections and or resistor strip.
I found there to be differences in ohm's reading hot and cold while field testing different sensor's in the kitchen with my wife's candy thermometer, and a pan of water on her stove.
Before installing the new gauge, I wired it up in the kitchen and put it thru it's paces, and for a $35 gauge, I was happy.
If I am remembering correctly, at ambient room temp, say '86-degrees, you should be getting a reading of either high or low.
I never had any luck getting my old gauge to read properly with whatever sensor I used, so my cluster gauge must have some sort of continuity issue with connections and or resistor strip.
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