Glend wrote:
James, happy to help out, just don't call me in the middle of the night. Don't forget that my scanner cannot read the TCM bus, we are seeing the OBDII code output
Here is what my service manual has to say about diagnostics for this fault: (my suggestion is at the end of all of this)
P0725-ENGINE SPEED SENSOR CIRCUIT
For a complete wiring diagram Refer to Section 8W.
² When Monitored:
Continuously every 7 msec with the ignition on and engine running.
² Set Condition:
This DTC will set when the calculated engine speed is less than 390 RPM with the engine running, or greater
than 8000 RPM, for the period of 2.0 seconds. The TCM will place the Transmission in Limp-in when this DTC
is set. Note: This is not a Transmission Input Speed Sensor DTC.
Possible Causes
RELATED ENGINE DTC’S PRESENT
ENGINE RPM SIGNAL CIRCUIT OPEN
ENGINE RPM SIGNAL CIRCUIT SHORT TO GROUND
ENGINE RPM SIGNAL CIRCUIT SHORT TO VOLTAGE
TRANSMISSION CONTROL MODULE
POWERTRAIN CONTROL MODULE
Always perform the 45RFE/545RFE Pre-Diagnostic Troubleshooting Procedure before proceeding. (Refer to
21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 45RFE/545RFE - STANDARD PROCEDURE)
Theory of Operation
The Transmission Control System calculates the engine RPM by directly reading the engine crank position sensor.
It compares the calculated value to the engine speed sensor signal transmitted from the Engine Control System
over the Engine RPM Signal circuit. The calculated engine RPM is also compared to a minimum and a maximum
value.
Diagnostic Test
1. CHECK FOR RELATED ENGINE DTCS
NOTE: This is not a Transmission Input Speed Sensor DTC.
Ignition on, engine not running.
With the scan tool, read all Engine DTCs. This includes any active or stored or one trip DTCs.
Are there any engine RPM related DTCs present?
Yes >> Refer to the Powertrain category and perform the appropriate symptom.
Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1. (Refer to 21 - TRANSMISSION/
TRANSAXLE/AUTOMATIC - 45RFE/545RFE - STANDARD PROCEDURE)
No >> Go To 2
2. CHECK IF THE DTC IS CURRENT
Ignition on, engine not running.
With the scan tool, check the Starts Since Set counter for this DTC.
Is the Starts Since Set counter 2 or less?
Yes >> Repair the (K244) Engine RPM Signal circuit for a short to voltage.
Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1. (Refer to 21 - TRANSMISSION/
TRANSAXLE/AUTOMATIC - 45RFE/545RFE - STANDARD PROCEDURE)
No >> Go To 3
3. CHECK THE (K244) ENGINE RPM SIGNAL CIRCUIT FOR AN OPEN
Turn the ignition off to the lock position.
Disconnect the TCM harness connector.
Disconnect the ECM harness connector.
Measure the resistance of the (K244) Engine RPM Signal circuit between the TCM harness connector and the ECM
harness connector.
Is the resistance above 5.0 ohms?
Yes >> Repair the (K244) Engine RPM Signal circuit for an open
Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1. (Refer to 21 - TRANSMISSION/
TRANSAXLE/AUTOMATIC - 45RFE/545RFE - STANDARD PROCEDURE)
No >> Go To 4
4. CHECK THE (K244) ENGINE RPM SIGNAL CIRCUIT FOR A SHORT TO GROUND
Measure the resistance between ground and the (K244) Engine RPM Signal circuit.
Is the resistance below 5.0 ohms?
Yes >> Repair the (K244) Engine RPM Signal circuit for a short to ground.
Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1. (Refer to 21 - TRANSMISSION/
TRANSAXLE/AUTOMATIC - 45RFE/545RFE - STANDARD PROCEDURE)
No >> Go To 5
5. CHECK THE (K244) ENGINE RPM SIGNAL CIRCUIT FOR A SHORT TO VOLTAGE
Ignition on, engine not running.
Check the voltage of the (K244) Engine RPM Signal circuit.
Is the voltage above 0.5 volts?
Yes >> Repair the (K244) Engine RPM Signal circuit for a short to voltage.
Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1. (Refer to 21 - TRANSMISSION/
TRANSAXLE/AUTOMATIC - 45RFE/545RFE - STANDARD PROCEDURE)
No >> Go To 6
6. CHECK THE TCM
Turn the ignition off to the lock position.
Replace and program the TCM per the Service Information.
Start the engine and allow the engine to idle for 6 minutes.
Check the voltage of the (K244) Engine RPM Signal circuit.
Does the DTC reset?
Yes >> Replace the ECM per the Service Information.
Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1. (Refer to 21 - TRANSMISSION/
TRANSAXLE/AUTOMATIC - 45RFE/545RFE - STANDARD PROCEDURE)
No >> Test Complete.
Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1. (Refer to 21 - TRANSMISSION/
TRANSAXLE/AUTOMATIC - 45RFE/545RFE - STANDARD PROCEDURE
Because it comes good after allowing a cool down, and reappears after heating up, that you might have a sensor (or sensor component) open circuit or short that occurs when things heat up and expand. So my short answer is get Eddy to connect it up to the system at work and run the Transmission Verification Test. Make sure that they run it long enough for things to heat up to failure point. That's my suggestion. You really don't want to get down to Items 6 and 7 because things get really expensive then. Hopefully it is something like an intermittent crank position sensor or a wiring problem to a sensor.
Does Eddie do house calls? lol can u pm eddie's contact details so I can give him a call.
cheers james