CHT sensor
Thread Starter
Junior Member
Joined: Jul 2019
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CHT sensor
Truck is a 2002 Ford f150 5.4L.
I have recently started having a warm startup issue with my truck. Only way
it will start is using flood mode. Temperature gauge works and is in normal
range but when I pull live data from the computer I am getting a fluctuating
number that jumps back and forth between 84 degrees and -34. Both
numbers are incorrect since the truck is running at its normal 192 degrees. I
assumed the CHT sensor was bad so replaced it and no change. I am
wondering where this sensor grounds? This must be a electrical short
somewhere. Any advise would be great . Thank you
I have recently started having a warm startup issue with my truck. Only way
it will start is using flood mode. Temperature gauge works and is in normal
range but when I pull live data from the computer I am getting a fluctuating
number that jumps back and forth between 84 degrees and -34. Both
numbers are incorrect since the truck is running at its normal 192 degrees. I
assumed the CHT sensor was bad so replaced it and no change. I am
wondering where this sensor grounds? This must be a electrical short
somewhere. Any advise would be great . Thank you
Member
Joined: Jan 2018
Posts: 11,256
Likes: 1,770
From: Memphis, TN, Earth, Milky Way
It grounds to the head where it's screwed in - that's what grounding means. If you want to see where its return wire goes, look for that wiring diagram at this link:
http://www.bbbind.com/tsb-wiring-diagrams-database/
No, it doesn't have to be a short - it could be an open (the opposite of a short), or high resistance. And the fault doesn't have to be in the CHT circuit - it could be in some related circuit inside or outside the PCM. It could even be at the battery terminals - what do they look like? Are you sure the live data you were watching came from the CHT? It could also come from the MAF, ACT, or ECT.
http://www.bbbind.com/tsb-wiring-diagrams-database/
No, it doesn't have to be a short - it could be an open (the opposite of a short), or high resistance. And the fault doesn't have to be in the CHT circuit - it could be in some related circuit inside or outside the PCM. It could even be at the battery terminals - what do they look like? Are you sure the live data you were watching came from the CHT? It could also come from the MAF, ACT, or ECT.
Thread Starter
Junior Member
Joined: Jul 2019
Posts: 2
Likes: 0
It grounds to the head where it's screwed in - that's what grounding means. If you want to see where its return wire goes, look for that wiring diagram at this link:
http://www.bbbind.com/tsb-wiring-diagrams-database/
No, it doesn't have to be a short - it could be an open (the opposite of a short), or high resistance. And the fault doesn't have to be in the CHT circuit - it could be in some related circuit inside or outside the PCM. It could even be at the battery terminals - what do they look like? Are you sure the live data you were watching came from the CHT? It could also come from the MAF, ACT, or ECT.
http://www.bbbind.com/tsb-wiring-diagrams-database/
No, it doesn't have to be a short - it could be an open (the opposite of a short), or high resistance. And the fault doesn't have to be in the CHT circuit - it could be in some related circuit inside or outside the PCM. It could even be at the battery terminals - what do they look like? Are you sure the live data you were watching came from the CHT? It could also come from the MAF, ACT, or ECT.
Member
Joined: Jan 2018
Posts: 11,256
Likes: 1,770
From: Memphis, TN, Earth, Milky Way
(phone app link)
If the alternator is a 3G, this caption explains how it works & how to test it:
(phone app link)
For any alternator, do this:
(phone app link)
(phone app link)