Hey there I'm Frank
I have a 2000 Excursion 6.8l. I am having an issue with my CHT... I've replace it three times now... I've replaced the thermastat, flushed the coolant and disconnected the trailer brake harness, and im still getting a p1289 code.... anyone have any guidance?

 

Welcome to the forums, not sure about the X but here is generall what a P1289 indicates

P1289 Ford - Cylinder Head Temperature Sensor Signal Greater Than Self-Test Range some of your possible causes are listed below...

- Wrong thermostat
- Not at operating range
- Engine overheated
- Low engine coolant level
- Faulty Cylinder Head Temperature (CHT) sensor
- Cylinder Head Temperature (CHT) sensor harness is open or shorted
- Cylinder Head Temperature (CHT) sensor circuit poor electrical connection

The Engine Control Module (ECM) detected the cylinder head temp above or below expected values (which should be triggering your CEL), have you cleared the codes to ensure your not getting stored OLD codes??

I assume you have a basic understanding of whats going on but here is a brief rundown of whats really going on The Cylinder Head Temperature (CHT from here on out) Sensor is mounted into the wall of the cylinder head and is not connected to any coolant passages. The CHT sends a signal to the Powertrain Control Module (PCM from here on out) indicating the cylinder head temperature. If the temperature exceeds 126°C (-258°F), the PCM disables four fuel injectors at a time. The PCM will alternate which four injectors are disabled every 32 engine cycles. The four cylinders that are not being fuel injected act as air pumps to aid in cooling the engine. If the temperature exceeds 154 °C (310°F), the PCM disables all of the fuel injectors until the engine temperature drops below 154°C (310°F).


hope this helps some, again im just going off what I know about the good ol Fords

 

Thanks for joining Frank

Tony

 

Thanks guys.... would you guys happen to have or can point me to a wiring schematic for my truck?

 

Sadly thats where my abilities will come to an end, but if you have a Haynes book or Chiltons, while not a full Ford tech manual they will have wireing diagrames for your vehicle and would be a worth while investment anyways, so I would go out and buy a book or two.