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Starting System: Overview Ford Expedition III

Starter 15 illustrations ~2528 words

Normal Operation

Under normal operation, when the ignition switch is turned to the START position and released, the PCM receives a starter motor request signal through circuit CDC35 (BU/WH), power is then supplied to the starter relay through circuit CDC38 (WH/VT) from the PCM. The PCM will receive a signal from the transmission that the vehicle is in PARK or NEUTRAL through circuit CET40 (GN/OG). A ground is supplied through circuit CDC12 (YE) from the PCM causing the starter relay coil to energize and the relay contacts close. This allows power to be supplied from Battery Junction Box (BJB) fuse 13 (30A) to the relay contacts which then flows through circuit CDC25 (BN/GN) to the starter solenoid. The solenoid is grounded at the starter motor. Energizing the starter solenoid will engage the starter drive into the ring gear and closes the solenoid contacts allowing power directly from the battery through circuit SDC02 (RD) to the starter motor to start the engine. The PCM will disengage the starter motor based on engine running (RPM threshold), a set crank time has been exceeded or the ignition switch has been turned to the OFF position.

This pinpoint test is intended to diagnose the following

  1. Anti-theft system
  2. Battery
  3. Circuitry
  4. Ignition switch
  5. PCM
  6. Park/Neutral Position (PNP) switch (integral to the mechatronics unit)
  7. Start diode
  8. Starter motor
  9. Starter motor relay

Scheme 1

Scheme 1: PINPOINT TEST A: THE ENGINE DOES NOT CRANK
Scheme 1: PINPOINT TEST A: THE ENGINE DOES NOT CRANK

Scheme 2

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Scheme 5

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Scheme 7

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Scheme 13

Scheme 13
Scheme 13
  1. A1 CHECK THE BATTERY Check the battery condition and charge. Refer to «BATTERY, MOUNTING AND CABLES»(ref-364088) . Is the battery OK? Yes: GO to A2 . No: CHARGE or INSTALL a new battery as necessary. REFER to «BATTERY, MOUNTING AND CABLES»(ref-364088) . TEST the system for normal operation.
  2. A2 CHECK THE PCM FOR DTCs Check for PCM DTCs. Were any PCM DTCs retrieved? Yes: If PCM DTC P1260 is retrieved, REFER to «ANTI-THEFT - PASSIVE ANTI-THEFT SYSTEM (PATS)»(ref-364086) . All other PCM DTCs, REFER to «INTRODUCTION - GASOLINE MODELS»(ref-355661) . No: GO to A3 .
  3. A3 CHECK THE PCM TR SENSOR PID Enter the following diagnostic mode on the scan tool: DataLogger - PCM. While observing the PCM TR sensor PID, place the vehicle in PARK and NEUTRAL. Does the PID match the gear selection? Yes: GO to A4 . No: REFER to the Park Neutral Circuit Pinpoint Test to diagnose the transmission. REFER to «AUTOMATIC TRANSAXLE/TRANSMISSION - 6R80»(ref-364034) .
  4. A4 CHECK THE BATTERY GROUND CABLE Measure the voltage between the positive battery post and the battery ground cable connection at the engine. Is the voltage greater than 10 volts? Yes: GO to A5 . No: INSTALL a new battery ground cable. REFER to «BATTERY, MOUNTING AND CABLES»(ref-364088) . TEST the system for normal operation.
  5. A5 CHECK THE STARTER MOTOR GROUND Measure the voltage between the positive battery post and the starter motor case. Is the voltage greater than 10 volts? Yes: GO to A6 . No: CLEAN the starter motor mounting flange and VERIFY the starter motor is correctly mounted. TEST the system for normal operation.
  6. A6 CHECK THE POWER SUPPLY TO THE STARTER MOTOR Measure the voltage between starter motor C197A-1, circuit SDC02 (RD) and ground. Is the voltage greater than 10 volts? Yes: GO to A7 . No: INSTALL a new positive battery cable. REFER to «BATTERY, MOUNTING AND CABLES»(ref-364088) . TEST the system for normal operation.
  7. A7 MANUALLY JUMP THE STARTER MOTOR Connect one end of a fused jumper wire to starter motor solenoid terminal C197A-1, circuit SDC02 (RD). Momentarily connect the other end of the jumper to starter motor solenoid terminal C197B-1, circuit CDC25 (BN/GN). Did the starter motor engage and the engine crank? Yes: GO to A8 . No: INSTALL a new starter motor. REFER to «STARTER MOTOR»(ref-364100-S40404461892010062700000) . TEST the system for normal operation.
  8. A8 CHECK THE START INPUT TO THE STARTER MOTOR Disconnect: Starter S-Connector. Key in START position. Measure the voltage at the starter motor solenoid S-connector C197B-1, circuit CDC25 (BN/GN). Is the voltage reading greater than 10 volts? Yes: CLEAN the starter motor solenoid S-terminal and connector. CHECK the wiring and the starter motor for a loose or intermittent connection. TEST the system for normal operation. No: GO to A9 .
  9. A9 CHECK CIRCUIT CDC25 (BN/GN) FOR AN OPEN NOTE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector. Disconnect: Starter Solenoid S-Connector. Measure the resistance of circuit CDC25 (BN/GN) between starter relay pin cavity 5 and the starter solenoid S-connector C197B-1, circuit CDC25 (BN/GN). Is the resistance reading 5 ohms or less? Yes: GO to A10 . No: REPAIR circuit CDC25 (BN/GN) for an open. TEST the system for normal operation.
  10. A10 CHECK FOR START INPUT AT THE STARTER MOTOR RELAY NOTE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector. Disconnect: Starter Motor Relay. Measure the voltage between starter motor relay pin cavity 1, circuit CDC38 (WH/VT) and ground with the ignition switch in the START position. Is the voltage greater than 10 volts? Yes: GO to A11 . No: GO to A13 .
  11. A11 CHECK THE BATTERY SUPPLY TO THE STARTER RELAY NOTE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector. Disconnect: Starter Motor Relay. Measure the voltage at starter motor relay pin cavity 3. Is the voltage reading greater than 10 volts? Yes: GO to A12 . No: VERIFY the BJB fuse 13 (30A) is OK. If OK, REPAIR circuit SDC04 (RD). If not OK, REFER to the «SYSTEM WIRING DIAGRAMS»(ref-360976) (Expedition), «SYSTEM WIRING DIAGRAMS»(ref-360977) (Expedition EL), «SYSTEM WIRING DIAGRAMS»(ref-360997) (Navigator) or «SYSTEM WIRING DIAGRAMS»(ref-360998) (Navigator L) to identify the possible causes of the circuit short.
  12. A12 CHECK FOR STARTER MOTOR RELAY GROUND NOTE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector. Disconnect: Starter Motor Relay. Key in START position. Measure the voltage between starter motor relay pin cavity 1, circuit CDC38 (WH/VT) and pin cavity 2, circuit CDC12 (YE). Is the voltage greater than 10 volts? Yes: INSTALL a new starter motor relay. TEST the system for normal operation. No: GO to A17 .
  13. A13 CHECK THE START DIODE Disconnect: Start Diode. Check the start diode. Is the start diode open or shorted? Yes: INSTALL a new start diode. TEST the system for normal operation. No: GO to A14 .
  14. A14 CHECK CIRCUIT CDC35 (BU/WH) FOR VOLTAGE AT THE START DIODE NOTE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector. Disconnect: Start Diode. Measure the voltage between start diode cavity C1-60-1, circuit CDC35 (BU/WH) and ground with the ignition switch in the START position. Is the voltage greater than 10 volts? Yes: REPAIR circuit CDC38 (WH/VT). TEST the system for normal operation. No: GO to A15 .
  15. A15 CHECK CIRCUIT SBP27 (BU/RD) FOR VOLTAGE NOTE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector. Disconnect: Ignition Switch C250. Measure the voltage between ignition switch C250-9, circuit SBP27 (BU/RD), harness side and ground. Is the voltage greater than 10 volts? Yes: GO to A16 . No: REPAIR circuit SBP27 (BU/RD). TEST the system for normal operation.
  16. A16 CHECK THE IGNITION SWITCH Carry out the Ignition Switch Component Test. Refer to «COMPONENT TESTING»(ref-356049) for component testing. Did the ignition switch pass the component test? Yes: REPAIR circuit CDC35 (BU/WH). TEST the system for normal operation. No: INSTALL a new ignition switch. REFER to «STEERING COLUMN SWITCHES»(ref-364062) . TEST the system for normal operation.
  17. A17 CHECK CIRCUIT CDC12 (YE) FOR AN OPEN NOTE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector. Disconnect: PCM C175B. Measure the resistance between the starter motor relay pin cavity 2, circuit CDC12 (YE) and PCM C175B-7, circuit CDC12 (YE). Is the resistance reading 5 ohms or less? Yes: DIAGNOSE the PCM. REFER to the «INTRODUCTION - GASOLINE MODELS»(ref-355661) . No: REPAIR circuit CDC12 (YE) for an open. TEST the system for normal operation.

Under normal operation, when the ignition switch is turned to the START position and released, the PCM receives a starter motor request signal through circuit CDC35 (BU/WH), power is then supplied to the starter relay through circuit CDC38 (WH/VT) from the PCM. The PCM will receive a signal from the transmission that the vehicle is in PARK or NEUTRAL through circuit CET40 (GN/OG). A ground is supplied through circuit CDC12 (YE) from the PCM causing the starter relay coil to energize and the relay contacts close. This allows power to be supplied from Battery Junction Box (BJB) fuse 13 (30A) to the relay contacts which then flows through circuit CDC25 (BN/GN) to the starter solenoid. The solenoid is grounded at the starter motor. Energizing the starter solenoid will engage the starter drive into the ring gear and closes the solenoid contacts allowing power directly from the battery through circuit SDC02 (RD) to the starter motor to start the engine. The PCM will disengage the starter motor based on engine running (RPM threshold), a set crank time has been exceeded or the ignition switch has been turned to the OFF position.

This pinpoint test is intended to diagnose the following

  1. Circuitry
  2. PCM

Scheme 14

Scheme 14: PINPOINT TEST B: ONE-TOUCH INTEGRATED START (OTIS) DOES NOT OPERATE CORRECTLY
Scheme 14: PINPOINT TEST B: ONE-TOUCH INTEGRATED START (OTIS) DOES NOT OPERATE CORRECTLY
  1. B1 CHECK THE BATTERY Check the battery condition and charge. Refer to «BATTERY, MOUNTING AND CABLES»(ref-364088) . Is the battery OK? Yes: GO to B2 . No: CHARGE or INSTALL a new battery as necessary. REFER to «BATTERY, MOUNTING AND CABLES»(ref-364088) . TEST the system for normal operation.
  2. B2 CHECK THE PATS AND PCM FOR DTCs Check for Passive Anti-Theft System (PATS) and PCM DTCs. Were any PATS and PCM DTCs retrieved? Yes: REFER to «ANTI-THEFT - PASSIVE ANTI-THEFT SYSTEM (PATS)»(ref-364086) to diagnose the PATS DTCs. REFER to «INTRODUCTION - GASOLINE MODELS»(ref-355661) to diagnose the PCM DTCs. No: GO to B3 .
  3. B3 CHECK THE STATUS OF OTIS (OTS_STAT) PID Enter the following diagnostic mode on the scan tool: DataLogger - PCM. Monitor the PCM PID OTS_STAT with the ignition switch in the RUN position. Is the One-Touch Integrated Start (OTIS) PID enabled? Yes: GO to B4 . No: ENABLE OTIS . TEST the system for normal operation. If OTIS will not enable, DIAGNOSE the PCM. REFER to «INTRODUCTION - GASOLINE MODELS»(ref-355661) .
  4. B4 CHECK THE KEY POSITION FOR START INDICATED (START_KEY) PID Enter the following diagnostic mode on the scan tool: DataLogger - PCM. Monitor the PCM PID START_KEY with the ignition switch in the START position. Does the PID change from OFF to ON? Yes: GO to B6 . No: GO to B5 .
  5. B5 CHECK THE TR SENSOR PID Enter the following diagnostic mode on the scan tool: DataLogger - PCM. While observing the PCM Transmission Range (TR) sensor PID, place the vehicle in PARK and NEUTRAL. Does the PID match the gear selection? Yes: GO to B6 . No: REFER to the Park Neutral Circuit Pinpoint Test to diagnose the transmission. REFER to «AUTOMATIC TRANSAXLE/TRANSMISSION - 6R80»(ref-364034) .
  6. B6 CHECK CIRCUIT CDC35 (BU/WH) FOR AN OPEN NOTE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector. Ignition OFF. Disconnect: PCM C175B. Disconnect: Start diode. Measure the resistance between start diode cell, circuit CDC35 (BU/WH) and PCM C175B-16, circuit CDC35 (BU/WH), harness side. Is the resistance less than 5 ohms? Yes: DIAGNOSE the PCM. REFER to «INTRODUCTION - GASOLINE MODELS»(ref-355661) . No: REPAIR the circuit CDC35 (BU/WH). TEST the system for normal operation.

Under normal operation, when the ignition switch is turned to the START position and released, the PCM receives a starter motor request signal through circuit CDC35 (BU/WH), power is then supplied to the starter relay through circuit CDC38 (WH/VT) from the PCM. The PCM will receive a signal from the transmission that the vehicle is in PARK or NEUTRAL through circuit CET40 (GN/OG). A ground is supplied through circuit CDC12 (YE) from the PCM causing the starter relay coil to energize and the relay contacts close. This allows power to be supplied from Battery Junction Box (BJB) fuse 13 (30A) to the relay contacts which then flows through circuit CDC25 (BN/GN) to the starter solenoid. The solenoid is grounded at the starter motor. Energizing the starter solenoid will engage the starter drive into the ring gear and closes the solenoid contacts allowing power directly from the battery through circuit SDC02 (RD) to the starter motor to start the engine. The PCM will disengage the starter motor based on engine running (RPM threshold), a set crank time has been exceeded or the ignition switch has been turned to the OFF position.

This pinpoint test is intended to diagnose the following

  1. Battery
  2. Circuitry
  3. Ground circuit
  4. Starter motor

Scheme 15

Scheme 15: PINPOINT TEST C: THE ENGINE CRANKS SLOWLY
Scheme 15: PINPOINT TEST C: THE ENGINE CRANKS SLOWLY
  1. C1 CHECK THE BATTERY Check the battery condition and charge. Refer to «BATTERY, MOUNTING AND CABLES»(ref-364088) . Is the battery OK? Yes: GO to C2 . No: CHARGE or INSTALL a new battery as necessary. REFER to «BATTERY, MOUNTING AND CABLES»(ref-364088) . TEST the system for normal operation.
  2. C2 CHECK THE VOLTAGE TO THE STARTER Ignition OFF. Measure the voltage between starter motor terminal C197A-1, circuit SDC02 (RD) and ground. Is the voltage 10 volts or greater? Yes: GO to C3 . No: REPAIR circuit SDC02 (RD). CLEAN and TIGHTEN the connections at the battery terminals. TEST the system for normal operation.
  3. C3 CHECK MOTOR GROUND CIRCUIT Carry out the Motor Ground Circuit Test. Refer to the «COMPONENT TESTS»(ref-364100-S01330255742010062700000) . Is the ground OK? Yes: INSTALL a new starter motor. TEST the system for normal operation. No: REPAIR the ground circuit as necessary. TEST the system for normal operation.

Under normal operation, when the ignition switch is turned to the START position and released, the PCM receives a starter motor request signal through circuit CDC35 (BU/WH), power is then supplied to the starter relay through circuit CDC38 (WH/VT) from the PCM. The PCM will receive a signal from the transmission that the vehicle is in PARK or NEUTRAL through circuit CET40 (GN/OG). A ground is supplied through circuit CDC12 (YE) from the PCM causing the starter relay coil to energize and the relay contacts close. This allows power to be supplied from Battery Junction Box (BJB) fuse 13 (30A) to the relay contacts which then flows through circuit CDC25 (BN/GN) to the starter solenoid. The solenoid is grounded at the starter motor. Energizing the starter solenoid will engage the starter drive into the ring gear and closes the solenoid contacts allowing power directly from the battery through circuit SDC02 (RD) to the starter motor to start the engine. The PCM will disengage the starter motor based on engine running (RPM threshold), a set crank time has been exceeded or the ignition switch has been turned to the OFF position.

This pinpoint test is intended to diagnose the following

  1. Starter motor mounting
  2. Starter motor mounting bolts
  3. Starter motor drive
  4. Flywheel or flexplate ring gear
  5. Starter motor

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