Temp Gauge on Dash

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Apr 29, 2015 | 12:31 PM

Raymond

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Tuned

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From: Eastern TN

Temp Gauge on Dash

I noticed the other day on my 04 F350 that the temp gauge does not move at all. Where is the temp sending unit located at so I can replace it? I assumed it would be on the front of the engine like older Ford engines but I'm not seeing one.

Thanks

Apr 29, 2015 | 08:19 PM

projectSHO89

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From: St Louis

You'd probably be wasting your time and there isn't a gauge sensor.

Apr 30, 2015 | 01:20 PM

Raymond

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Tuned

Joined: Oct 1999

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From: Eastern TN

So if there is a sending unit for the gauge, how does it get its signal?

Apr 30, 2015 | 07:32 PM

projectSHO89

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From: St Louis

It's a calculated value based on the input from the CHT sensor. Computer stuff.

May 1, 2015 | 12:24 PM

Raymond

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From: Eastern TN

Ok so where is the CHT sensor located at and can it be changed?

May 1, 2015 | 01:31 PM

projectSHO89

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From: St Louis

You'd better do some more homework and data gathering before jumping off that bridge. So far, you have no evidence that it's a sensor issue.

May 14, 2015 | 07:28 AM

F150Torqued

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From: San Antonio, Texas

that magical CHT sensor under the intake manifold

@Raymond, @projectSHO89 is right. The following link will quickly shed some light on the subject.

Diagnosing Ford?s Cylinder Head Temperature (CHT) Sensor | Search Autoparts

If your CHT sensor isn't working, there would undoubtedly be other symptoms. It is used by the PCM for numerous things, one of which is determining if the O2 Sensor heaters come up to temperature within the proper amount of time ( See the detailed description for P0135 Ford O2 Sensor Heater Circuit Malfunction Bank 1 Sensor 1 OBDII Engine Light Trouble Code | Engine-Codes.com ), and drive cycle counts, and as @project SHO89 says - coolant temperature itself.

I spent a great deal of time trying to HACK the Ford custom Parameter ID # 1685 with my scan tool for an unrelated purpose. I ultimately found it is the Cylinder Head Temperature sensor Input. And it can be read with any scan tool, but the output is confusing to say the least. WHAT the PCM does with it is fascinating to say the least. It literally "calibrates" the senor at the beginning of each drive cycle. If it won't calibrate - you'll get a DTC code.

Calculated coolant temperature is posted at PID # 1139 and the one byte "Hexadecimal" value can be read with a scan tool such as Torque Pro. If that value is realistic, then the problem has to be after the PCM - ie the wiring, cluster or something else.

Hope my experience helps