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Hello, my name is***** and thanks for your question.
Engine size? 4.2L, 4.6L, 5.4L? Is it setting codes also in the PCM like P0116, P0119, P0125, P0128, P1116, P1285, P1288, P1289, P128A, P1290, or P1299?
Ok thanks. Those are all CHT codes. Any of them in particular?
Do you have the intake off or is it all together?
No voltage would indicate a short to ground in the wiring.
Usually with this code and symptom, its usually a wiring issue where the harness routes through the rear of the intake near the IMRC actuators. Has the wiring been thoroughly inspected in this area? If the intake was ever removed and the wiring was not was not routed exactly as from the factory or if all of the support clips not installed properly it will rub on the IMRC actuator rods causing a short. With the intake on its next to impossible to inspect. This all I have ever seen for this isuue. I have also seen rodent damage in that same area as they like to build nests in the valley.
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Do you have a scanner that can monitor/display PCM data?
The signal return for the CHT does not wire directly to the PCM, it goes to a splice where 10 wires join, then to the PCM. How did you account for that? My diagram shows the signal wire as yellow and light green stripe and signal return (ground) as gray/red stripe. Are these the same colors you have?
Yes but where exactly did you connect the new signal return wire from the cht?
OK, back to scanner. Key on engine off what is the data for the cht showing in temp and voltage? What is the EOT showing for temp and voltage? With the engine started and the fault occurs what is the data for the cht showing in temp and voltage? What is the EOT showing for temp and voltage?
OK. You eliminated (cut) the 2 original wires correct not splice in and overlay correct? New pigtail on the CHT?
If you disconnect the PCM connector and measure resistance across pins 41 and 58 what do you get? With the PCM still disconnected what resistance do you get from pin 41 to battery ground?
So 5.7 ohms across 41 and 58. See the attached chart. What does that tell you with 5.7 ohms across those pins. Chart is in Kohms
vref voltage potential will show zero if voltage is being consumed directly to ground.
Pretty much you have replaced everything plus wiring. If you are confident the wiring is good, I will opt out and give other experts a shot at this.
Hi my name is***** fault is likely a problem in the wiring harness somewhere after the parts you have already changed but these are the potential causes to throw that code. Let me know if any of these have not been confirmed as of yet.
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
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