LOST JEEPS :: View topic - Question about engine speed sensor P0725

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.

Author:	gi frog [ Mon Nov 01, 2010 4:17 am ]
Post subject:	Question about engine speed sensor P0725
Hi All, First off THANKS Glen for the rescue last wednesday and the use of the scan tool. This has happen four (4) time since wednesday . once/ wed afternoon twice/ fri afternoon Once / sat afternoon Symptoms 1: engine running time approx 20/25 mintues 2: Lose of power 3: oil light comes on and stay on audible chrime 4 engine shuts down When the Kj stop checked engine oil and transmission fluid. engine oil ok normal range for heated range transmission fluid a little low for heated range. Kj would not restart gave nrma(Glen) waited 20min for Glen to show up ,Glen put keys in and the Kj started took it home and topped the fluid up. it stop twice friday evening/night checked transmission fluid ok level checked fluid level saturday morning level ok stop sat afternoon,haven't driven Kj since. My questions are What does the (transmission engine speed sensor P0725) do? How to fix this problem? How much is it going to cost me? Should I take it to jeep to fix and clear the error code or specialist transmission mechanic.All expert advice welcome. Cheers James (gi frog)

Author:	Glend [ Mon Nov 01, 2010 7:28 am ]
Post subject:	Re: Question about engine speed sensor P07205
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.

Author:	gi frog [ Mon Nov 01, 2010 11:43 pm ]
Post subject:	Re: Question about engine speed sensor P07205
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

Author:	Glend [ Tue Nov 02, 2010 6:48 am ]
Post subject:	Re: Question about engine speed sensor P07205
James, I doubt Eddie would do house calls and even if he did he does not have a Jeep scan tool on him. You'll need to take to to him at his workshop. I have sent his numbers to you - but you should really ring his Service Booking number and ask them if he can look at it - going through channels you know. ANother alternative is to talk to him tomorrow night at the SJC meeting.

Author:	Glend [ Thu Nov 04, 2010 2:26 am ]
Post subject:	Re: Question about engine speed sensor P07205
James, Here is the information you needed on the input and output speed sensors on the transmission: SENSOR-OUTPUT SPEED DESCRIPTION The Input and Output Speed Sensors are two-wire magnetic pickup devices that generate AC signals as rotation occurs. They are mounted in the left side of the transmission case and are considered primary inputs to the Transmission Control Module (TCM). OPERATION The Input Speed Sensor provides information on how fast the input shaft is rotating. As the teeth of the input clutch hub pass by the sensor coil, an AC voltage is generated and sent to the TCM. The TCM interprets this information as input shaft rpm. The Output Speed Sensor generates an AC signal in a similar fashion, though its coil is excited by rotation of the rear planetary carrier lugs. The TCM interprets this information as output shaft rpm. The TCM compares the input and output speed signals to determine the following: ² Transmission gear ratio ² Speed ratio error detection ² CVI calculation The TCM also compares the input speed signal and the engine speed signal to determine the following: ² Torque converter clutch slippage ² Torque converter element speed ratio REMOVAL 1. Raise vehicle. 2. Place a suitable fluid catch pan under the transmission. 3. Remove the wiring connector from the output speed sensor (1). 4. Remove the bolt holding the output speed sensor (1) to the transmission case. 5. Remove the output speed sensor (1) from the transmission case. INSTALLATION 1. Install the output speed sensor (1) into the transmission case. 2. Install the bolt to hold the output speed sensor (1) into the transmission case. Tighten the bolt to 12 N·m (105 in.lbs.). 3. Install the wiring connector onto the output speed sensor (1). 4. Verify the transmission fluid level. Add fluid as necessary. 5. Lower vehicle. Sorry for some reason I cannot copy the diagram that shows the sensor position on the transmission. Good Luck, suggest you try cleaning the connectors and checking the wires before you consider removing the sensors are it sounds like fluid will leak out.

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