Test Procedure
WARNING: This page is about a different car, the 2007 Mercury Mariner and 2007 Ford Escape. However, it is still accessible from the selected car via links, so may be relevant.
- JH1 CONTINUOUS MEMORY DIAGNOSTIC TROUBLE CODES (DTC)S P0726 AND P0727: CLEAR AND RETRIEVE TRANSAXLE CONTROL MODULE (TCM) CONTINUOUS DTCS NOTE: Repair the PCM continuous memory DTC P0320 before proceeding any further.NOTE: Clearing the TCM DTCs will erase any TCM recorded freeze frame data. Make sure to record any TCM freeze frame information before proceeding any further. Refer to the scan tool instruction manual for freeze frame PID menu.
- Clear and retrieve TCM continuous DTCs.
- Are the TCM DTCs P0726 or P0727 present during self-test?
Yes No GO to JH2. CHECK the CTO circuit for an intermittent concern.
GO to JH8. - JH2 COMPARE TCM CALCULATED AND RECEIVED ENGINE RPM TO THE ACTUAL ENGINE RPM NOTE: The RPM PID indicates the engine speed the TCM calculated using generator speed. The ENG CTO PID indicates the engine speed the TCM receives from the PCM through the CTO circuit.NOTE: If the engine cranks but does not start, refer to the SYMPTOM CHARTS article, and Diagnose the No Start, Normal Crank symptom.
- Start the engine using the engine running diagnostic mode. Refer toDIAGNOSTIC MODES .
- Allow the engine to idle at the normal operating temperature.
- Access the TCM and monitor the RPM and ENG CTO PIDs.
- Are both RPM PID readings within 1,000 RPM range of engine idle RPM?
Yes No INSTALL a new transaxle assembly. REFER to AUTOMATIC TRANSAXLE/TRANSMISSION - ELECTRONICALLY CONTROLLED CONTINUOUSLY VARIABLE TRANSMISSION (ECVT) . GO to JH3. - JH3 CHECK THE CTO FOR A SHORT TO VOLTAGE IN THE HARNESS
- Transaxle Assembly-B connector disconnected.
- PCM connector disconnected.
- Key ON, engine OFF.
- Measure the voltage between:
( + ) Transaxle Assembly-B Connector, Harness Side ( - ) Vehicle Battery CTO - Pin 1 Negative terminal - Is the voltage less than 1 V?
Yes No GO to JH4. REPAIR the circuit.
CLEAR the DTCs. REPEAT the self-test. - JH4 CHECK THE CTO CIRCUIT FOR A SHORT TO GND IN THE HARNESS
- Key in OFF position.
- Measure the resistance between:
( + ) Transaxle Assembly-B Connector, Harness Side ( - ) Vehicle Battery CTO - Pin 1 Negative terminal - Is the resistance greater than 10K ohms?
Yes No GO to JH5. REPAIR the circuit.
CLEAR the DTCs. REPEAT the self-test. - JH5 CHECK THE CTO CIRCUIT FOR AN OPEN IN THE HARNESS
- Measure the resistance between:
( + ) Transaxle Assembly-B Connector, Harness Side ( - ) PCM Connector, Harness Side CTO - Pin 1 CTO - Pin T46 - Is the resistance less than 5 ohms?
Yes No GO to JH6. REPAIR the circuit.
CLEAR the DTCs. REPEAT the self-test. - Measure the resistance between:
- JH6 CHECK FOR THE CTO CIRCUIT SHORTED TO SIGNALS IN THE SAME HARNESS
- Measure the resistance between:
( + ) Transaxle Assembly-B Connector, Harness Side ( - ) Transaxle Assembly-B Connector, Harness Side CTO - Pin 1 GSDN - Pin 10 CTO - Pin 1 ISDN2 - Pin 7 CTO - Pin 1 MSDN - Pin 5 CTO - Pin 1 TGAC - Pin 9 CTO - Pin 1 TMAC - Pin 4 - Are the resistances greater than 10K ohms?
Yes No GO to JH7. REPAIR the circuit.
CLEAR the DTCs. REPEAT the self-test. - Measure the resistance between:
- JH7 CHECK THE CTO SIGNAL FROM THE PCM CAUTION: While conducting checks with a running engine make sure adequate safety precautions are observed to prevent contact with moving engine parts. For example make sure ties or loose clothing do not come into contact with the cooling fan or drive belts.
- PCM connector connected.
- Transaxle Assembly-B connector connected.
- Isolate the CTO pin from the transaxle-B connector.
- Start the engine using the engine running diagnostic mode. Refer toDIAGNOSTIC MODES .
- Measure the frequency between:
( + ) Transaxle Assembly-B Connector, Harness Side ( - ) Vehicle Battery CTO - Pin 1 Negative terminal - Is the frequency between 15 - 155 Hz?
Yes No INSTALL a new transaxle assembly. REFER to AUTOMATIC TRANSAXLE/TRANSMISSION - ELECTRONICALLY CONTROLLED CONTINUOUSLY VARIABLE TRANSMISSION (ECVT) . GO to JH9. - JH8 CHECK THE CTO CIRCUIT FOR INTERMITTENT CONCERNS CAUTION: While conducting checks with a running engine ensure adequate safety precautions are observed to prevent contact with moving engine parts. For example, make sure ties or loose clothing do not come into contact with the cooling fan or drive belts.
- Start the engine using the engine running diagnostic mode. Refer toDIAGNOSTIC MODES .
- Access the TCM and monitor the ENG_CTO PID.
- Carefully wiggle all accessible wiring and connectors associated with the circuit and look for a change in the PID state.
- Is a concern indicated during the wiggle test?
Yes No REPAIR as necessary.
CLEAR the DTCs. REPEAT the self-test.refer to PINPOINT TEST Z . - JH9 CHECK FOR CORRECT PCM OPERATION
- Disconnect all the PCM connectors.
- Visually inspect for:
- pushed out pins
- corrosion
- Connect all the PCM connectors and make sure they seat correctly.
- Carry out the PCM self-test and verify the concern is still present.
- Is the concern still present?
Yes No INSTALL a new PCM.
REFER toFLASH ELECTRICALLY ERASABLE PROGRAMMABLE READ ONLY MEMORY (EEPROM) .The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.