JH - Test
JH: Engine Speed Signal
JH: Introduction JH - Introduction
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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
GO to JH2.
NO
CHECK the CTO circuit for an intermittent concern.
GO to JH8.
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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 Symptom Charts Symptom Related Diagnostic Procedures , and Diagnose the No Start, Normal Crank symptom.
- Start the engine using the engine running diagnostic mode. Refer to Diagnostic Modes Diagnostic Modes.
- Allow the engine to idle at the normal operating temperature.
- Access the TCM and monitor the ENGRPMA and ENG_CTO PIDs.
Are both RPM PID readings within 1,000 RPM range of engine idle RPM?
YES
INSTALL a new transaxle assembly. REFER to Automatic Transaxle/Transmission.
NO
GO to JH3.
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JH3 CHECK THE CTO FOR A SHORT TO VOLTAGE IN THE HARNESS
- Transaxle Assembly-B connector disconnected.
- PCM connector disconnected.
- Ignition ON, engine OFF.
- Measure the voltage between:
Is the voltage less than 1 V?
YES
GO to JH4.
NO
REPAIR the circuit.
CLEAR the DTCs. REPEAT the self-test.
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JH4 CHECK THE CTO CIRCUIT FOR A SHORT TO GND IN THE HARNESS
- Ignition OFF.
- Measure the resistance between:
Is the resistance greater than 10K ohms?
YES
GO to JH5.
NO
REPAIR the circuit.
CLEAR the DTCs. REPEAT the self-test.
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JH5 CHECK THE CTO CIRCUIT FOR AN OPEN IN THE HARNESS
- Measure the resistance between:
Is the resistance less than 5 ohms?
YES
GO to JH6.
NO
REPAIR the circuit.
CLEAR the DTCs. REPEAT the self-test.
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JH6 CHECK FOR THE CTO CIRCUIT SHORTED TO SIGNALS IN THE SAME HARNESS
- Measure the resistance between:
Are the resistances greater than 10K ohms?
YES
GO to JH7.
NO
REPAIR the circuit.
CLEAR the DTCs. REPEAT the self-test.
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JH7 CHECK THE CTO SIGNAL FROM THE PCM
NOTICE: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 to Diagnostic Modes Diagnostic Modes.
- Measure the frequency between:
Is the frequency between 15 - 155 Hz?
YES
INSTALL a new transaxle assembly. REFER to Automatic Transaxle/Transmission.
NO
GO to JH9.
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JH8 CHECK THE CTO CIRCUIT FOR INTERMITTENT CONCERNS
NOTICE: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 to Diagnostic Modes Diagnostic 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
REPAIR as necessary.
CLEAR the DTCs. REPEAT the self-test.
NO
GO to Pinpoint Test Z Z - Introduction.
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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
INSTALL a new PCM.
REFER to Flash Electrically Erasable Programmable Read Only Memory (EEPROM) Flash Electrically Erasable Programmable Read Only Memory (EEPROM).
NO
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.