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Starting System: Overview Mercury Sable V

Starter 13 illustrations ~1742 words

Principles of Operation

The starting system is electronically controlled by the passive anti-theft system (PATS). The PATS recognizes the correct electronically coded ignition key and signals the PCM to provide a ground for the starter relay. The energized relay provides voltage to the starter solenoid with the key in the START position, thereby allowing the starter motor to activate.

Normal Operation

Under normal operation, constant power is supplied to the starter motor relay on circuit SBB10 (YE/RD). When the ignition switch is turned in the START position and held, with the vehicle in PARK or NEUTRAL, power flows to the starter motor relay through CE336 (GN/WH). A ground is supplied through circuit CDC12 (YE) from the PCM causing the starter motor relay coil to energize and the relay contacts close. This allows power to be supplied from the starter motor 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.

This pinpoint test is intended to diagnose the following

  1. Battery
  2. Anti-theft system
  3. Starter relay
  4. Ignition switch
  5. Circuitry
  6. PCM
  7. Start diode

Scheme 3

Scheme 3: PINPOINT TEST A: THE ENGINE DOES NOT CRANK
Scheme 3: PINPOINT TEST A: THE ENGINE DOES NOT CRANK

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Scheme 13
  1. A1 CHECK THE BATTERY Check the battery condition and charge. Refer to «BATTERY, MOUNTING AND CABLES»(ref-293478) article. Is the battery OK? YES : Go to A2 . NO : CHARGE or INSTALL a new battery as necessary. REFER to «BATTERY, MOUNTING AND CABLES»(ref-293478) article. TEST the system for normal operation.
  2. A2 CHECK FOR PASSIVE ANTI-THEFT SYSTEM (PATS) DTCs NOTE: PATS system DTCs are the only DTCs of concern in this step. Only repair retrieved non-PATS DTCs if a customer concern is reported. Check for PATS DTCs. Were any PATS DTCs retrieved? YES : REFER to «ANTI-THEFT - PASSIVE ANTI-THEFT SYSTEM (PATS)»(ref-293490) article to diagnose the PATS DTCs. NO : Go to A3 .
  3. A3 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 A4 . NO : INSTALL a new battery ground cable. REFER to «BATTERY, MOUNTING AND CABLES»(ref-293478) article. TEST the system for normal operation.
  4. A4 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 A5 . NO : CLEAN the starter motor mounting flange and make sure the starter motor is correctly mounted. TEST the system for normal operation.
  5. A5 CHECK THE POWER SUPPLY TO THE STARTER MOTOR Measure the voltage between starter motor C197a, circuit SDC02 (RD) and ground. Is the voltage greater than 10 volts? YES : Go to A6 . NO : INSTALL a new positive battery cable. REFER to «BATTERY, MOUNTING AND CABLES»(ref-293478) article. TEST the system for normal operation.
  6. A6 CHECK THE STARTER MOTOR B-PIN Connect one end of a fused (30A) jumper wire to starter motor solenoid C197b-a, circuit SDC02 (RD). Momentarily connect the other end of the jumper to starter motor C197b, circuit CDC25 (BN/GN). Did the starter motor engage and the engine crank? YES : Go to A7 . NO : INSTALL a new starter motor. REFER to «Starter Motor»(ref-293499-S09408905102008080700000) . TEST the system for normal operation.
  7. A7 CHECK STARTER MOTOR RELAY POWER CAUTION: 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 battery junction box (BJB) starter motor relay pin 30, circuit SBB10 (YE/RD), harness side and ground. Is the voltage greater than 10 volts? YES : Go to A8 . NO : REPAIR circuit SBB10 (YE/RD). TEST the system for normal operation.
  8. A8 CHECK THE STARTER MOTOR RELAY Carry out the Starter Motor Relay Component Test. Refer to appropriate COMPONENT TESTING article. Did the starter motor relay pass the component test? YES : Go to A9 . NO : INSTALL a new starter motor relay. TEST the system for normal operation.
  9. A9 CHECK THE CIRCUIT TO THE STARTER MOTOR Key in OFF position. Disconnect: Starter Motor Solenoid C197b Measure the resistance between starter motor solenoid S-terminal C197b, circuit CDC25 (BN/GN), harness side and the BJB starter motor relay pin 87, circuit CDC25 (BN/GN), harness side. Is the resistance less than 5 ohms? YES : Go to A10 . NO : REPAIR circuit CDC25 (BN/GN). TEST the system for normal operation.
  10. A10 CHECK CIRCUIT CDC35 (BU/WH) FOR VOLTAGE Connect: Starter Motor Solenoid C197b Connect: Starter Motor Relay Disconnect: Starter Diode Measure the voltage between BJB starter diode cell, circuit CDC35 (BU/WH) and ground with the ignition switch in the START position. Is the voltage greater than 10 volts? YES : Go to A13 . NO : Go to A11 .
  11. A11 CHECK CIRCUIT SBB33 (RD) FOR VOLTAGE Disconnect: Ignition Switch C250 Measure the voltage between ignition switch C250-4, circuit SBB33 (RD), harness side and ground. Is the voltage greater than 10 volts? YES : Go to A12 . NO : REPAIR circuit SBB33 (RD). TEST the system for normal operation.
  12. A12 CHECK THE IGNITION SWITCH Carry out the Ignition Switch Component Test. Refer to appropriate COMPONENT TESTING article. Did the ignition switch pass the component test? YES : REPAIR circuit CDC35 (BU/WH) for an open. TEST the system for normal operation. NO : INSTALL a new ignition switch. REFER to «STEERING COLUMN SWITCHES»(ref-293477) article. TEST the system for normal operation.
  13. A13 CHECK THE STARTER DIODE Carry out a Starter Diode Test. Is the starter diode open or shorted? YES : INSTALL a new starter diode. TEST the system for normal operation. NO : Go to A14 .
  14. A14 CHECK THE START SIGNAL TO THE STARTER MOTOR RELAY Connect: OTIS Diode Disconnect: Starter Motor Relay Measure the voltage between the BJB starter motor relay pin 85, circuit CE336 (GN/WH), harness side and ground with the ignition switch in the START position. Is the voltage greater than 10 volts? YES : Go to A15 . NO : REPAIR circuit CE336 (GN/WH) for an open. TEST the system for normal operation.
  15. A15 CHECK CIRCUIT CDC12 (YE) FOR AN OPEN Disconnect: PCM C175b Measure the resistance between the BJB starter relay pin 86, circuit CDC12 (YE), harness side and PCM C175b-34, circuit CDC12 (YE), harness side. Is the resistance less than 5 ohms? YES : INSTALL a new PCM. REFER to «ELECTRONIC ENGINE CONTROLS»(ref-293501) article. NO : REPAIR circuit CDC12 (YE). TEST the system for normal operation.

When the ignition switch is turned in the START position and released, the PCM receives a starter motor request (SMR) signal through circuit CDC35 (BU/WH). With the vehicle in PARK or NEUTRAL, power flows from the PCM to the starter motor relay through circuit CE336 (GN/WH). A ground is supplied through circuit CDC12 (YE) from the PCM causing the starter motor relay coil to energize and the relay contacts close. This allows power from starter motor relay 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 customer is no longer in the loop after the initial crank request, the customer may release the key to the RUN/START position. 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

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Scheme 15
Scheme 15
  1. B1 CHECK THE STATUS OF ONE-TOUCH INTEGRATED START (OTIS) (OTS_STAT) PID Enter the following diagnostic mode on the diagnostic tool: PCM DataLogger/PID NOTE: The vehicle must be in PARK for OTIS to operate. Monitor the PCM PID OTS_STAT with the ignition switch in the RUN position. Is the OTIS PID enabled? YES : Go to B2 . NO : Enable OTIS. TEST the system for normal operation. If OTIS will not enable, INSTALL a new PCM. REFER to «ELECTRONIC ENGINE CONTROLS»(ref-293501) article. TEST the system for normal operation.
  2. B2 CHECK THE KEY POSITION FOR START INDICATED (START_KEY) PID Enter the following diagnostic mode on the diagnostic tool: PCM DataLogger/PID 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 B4 . NO : Go to B3 .
  3. B3 CHECK CIRCUIT CDC35 (BU/WH) Disconnect: Start Diode Disconnect: PCM C175b Measure the resistance between the start diode cell, circuit CDC35 (BU/WH), harness side and PCM C175b-9, circuit CDC35 (BU/WH), harness side. Is the resistance less than 5 ohms? YES : INSTALL a new PCM. REFER to «ELECTRONIC ENGINE CONTROLS»(ref-293501) article. TEST the system for normal operation. NO : REPAIR circuit CDC35 (BU/WH). TEST the system for normal operation.
  4. B4 CHECK THE STARTER MOTOR RELAY ENABLE (STRT_RLY) PID Enter the following diagnostic mode on the diagnostic tool: PCM DataLogger/PID Monitor the PCM PID STRT_RLY with the ignition switch in the START position. Does the PID change from DISABLED to ENABLED? YES : Go to B6 . NO : Go to B5 .
  5. B5 CHECK THE CIRCUIT CE336 (GN/WH) BETWEEN THE BJB AND THE PCM Key in OFF position. Disconnect: PCM C175b Measure the resistance between the BJB starter motor relay pin 85, circuit CE336 (GN/WH), harness side and PCM C175b-35, circuit CE336 (GN/WH), harness side. Is the resistance less than 5 ohms? YES : INSTALL a new PCM. REFER to «ELECTRONIC ENGINE CONTROLS»(ref-293501) article. TEST the system for normal operation. NO : REPAIR circuit CE336 (GN/WH). TEST the system for normal operation.
  6. B6 CHECK THE STARTER MOTOR CONTROL OUTPUT DETECTED (SMC_MON) PID Enter the following diagnostic mode on the diagnostic tool: PCM DataLogger/PID Monitor the PCM PID SMC_MON with the ignition switch in the START position. Does the PID change from OFF to ON? YES : REPAIR circuit CDC12 (YE). TEST the system for normal operation. NO : INSTALL a new PCM. REFER to «ELECTRONIC ENGINE CONTROLS»(ref-293501) article. TEST the system for normal operation.

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