Ford Mustang (1999-2004) Service Manual: Pinpoint Tests

PINPOINT TEST A: THE ENGINE DOES NOT CRANK AND THE RELAY DOES CLICK

Test Step Result / Action to Take
A1 CHECK THE VOLTAGE TO THE STARTER RELAY Yes

GO to A2 .

No

REPAIR circuit 1050 (LG/VT) for an open. TEST the system for normal operation.
  • Measure the voltage between the starter relay pin 30, circuit 1050 (LG/VT) and ground.

  • Is the voltage greater than 12.5 volts?
A2 CHECK THE VOLTAGE TO THE STARTER MOTOR SOLENOID Yes

GO to A3 .

No

REPAIR circuit 2037 (RD) for an open. TEST the system for normal operation.
  • Measure the voltage between the starter motor solenoid positive terminal and ground.

  • Is the voltage 12.5 volts or greater?
A3 MANUALLY JUMP THE STARTER MOTOR Yes

GO to A4 .

No

INSTALL a new starter motor. REFER to Starter Motor-3.8L or Starter Motor-4.6L . TEST the system for normal operation.
  • Connect one end of a fused (15A) jumper wire to the positive terminal of the battery and touch the other end to the starter solenoid S-terminal.

  • Does the starter solenoid engage?
A4 TEST THE STARTER MOTOR RELAY Yes

REPAIR circuit 33 (WH/PK)/262 (BN/PK) for an open. TEST the system for normal operation.

No

INSTALL a new starter motor relay. TEST the system for normal operation.
  • Carry out the relay component test on the starter motor relay. Refer to the relay component test in this section.
  • Does the starter motor relay test good?

PINPOINT TEST B: THE ENGINE DOES NOT CRANK AND THE RELAY DOES NOT CLICK

Test Step Result / Action to Take
B1 CHECK CIRCUIT 33 (WH/PK) FOR VOLTAGE Yes

GO to B10 .

No

For automatic transmissions, GO to B2 . For manual transmissions, GO to B5 .
  • Disconnect: Starter Motor Relay.
  • Key in START position.
  • Measure the voltage between the starter motor relay pin 85, circuit 33 (WH/PK) and ground while holding the key in the START position.

  • Is the voltage greater than 10 volts?
B2 CHECK CIRCUIT 32 (RD/LB) FOR VOLTAGE AT THE DIGITAL TR SENSOR Yes

GO to B3 .

No

GO to B7 .
  • Key in OFF position.
  • Disconnect: Digital TR Sensor C110.
  • Key in START position.
  • Measure the voltage between the digital TR sensor C110 pin 10, circuit 32 (RD/LB) and ground while holding the key in the START position.

  • Is the voltage greater than 10 volts?
B3 CHECK CIRCUIT 33 (WH/PK) FOR OPEN Yes

GO to B4 .

No

REPAIR circuit 33 (WH/PK). TEST the system for normal operation.
  • Key in OFF position.

  • Measure the resistance between the digital TR sensor C110 pin 12, circuit 33 (WH/PK) and the starter motor relay pin 86, circuit 33 (WH/PK).
  • Is the resistance less than 5 ohms?
B4 CHECK DIGITAL TRANSMISSION RANGE (TR) SENSOR ADJUSTMENT Yes

INSTALL a new digital TR sensor. TEST the system for normal operation.

No

ADJUST the digital TR as necessary. TEST the system for normal operation.
  • Carry out the digital TR sensor adjustment. Refer to Section.
  • Is the digital TR sensor adjusted correctly?
B5 CHECK CIRCUIT 32 (RD/LB) FOR VOLTAGE AT THE CLUTCH SWITCH OR JUMPER Yes

GO to B6 .

No

GO to B7 .
  • Key in OFF position.
  • Disconnect: Clutch Pedal Switch C255.
  • Key in START position.
  • Measure the voltage between the clutch pedal switch C255 pin 2, circuit 32 (RD/LB) and ground while holding the key in the START position.

  • Is the voltage greater than 10 volts?
B6 CHECK CIRCUIT 33 (WH/PK)/32 (RD/LB) FOR OPEN Yes

INSTALL a new clutch pedal switch. TEST the system for normal operation.

No

REPAIR circuit 33 (WH/PK)/32 (RD/LB).

TEST the system for normal operation.
  • Key in OFF position.
  • Measure the resistance between the clutch pedal switch C255 pin 1, circuit 33 (WH/PK)/32 (RD/LB) and the starter motor relay pin 86, circuit 33 (WH/PK)/32 (RD/LB).

  • Is the resistance less than 5 ohms?
B7 CHECK FOR VOLTAGE AT FUSE 6 Yes

REPAIR circuit 32 (RD/LB). TEST the system for normal operation.

No

GO to B8 .
  • Key in OFF position.
  • Disconnect: Fuse #6.
  • Key in START position.
  • Measure the voltage between the central junction box fuse 6, circuit 33 (WH/PK) and ground while holding the key in the START position.

  • Is the voltage greater than 10 volts?
B8 CHECK CIRCUIT 1050 (LG/VT) FOR VOLTAGE Yes

GO to B9 .

No

REPAIR circuit 1050 (LG/VT). TEST the system for normal operation.
  • Key in OFF position.
  • Disconnect: Ignition Switch C209.
  • Key in ON position.
  • Measure the voltage between the ignition switch connector C209 pin B4, circuit 1050 (LG/VT) and ground.

  • Is the voltage greater than 10 volts?
B9 CHECK THE IGNITION SWITCH Yes

REPAIR circuit 33 (WH/PK). TEST the system for normal operation.

No

INSTALL a new ignition switch. TEST the system for normal operation.
  • Carry out the ignition switch component test. Refer to Refer to Wiring Diagrams Cell 149 for schematic and connector information.
  • Does the ignition switch test good?
B10 CHECK CIRCUIT 1205 (BK) FOR OPEN Yes

INSTALL a new starter motor relay. TEST the system for normal operation.

No

REPAIR circuit 1205 (BK). TEST the system for normal operation.
  • Key in OFF position.

  • Measure the resistance between the starter motor relay pin 86, circuit 1205 (BK) and ground.
  • Is the resistance less than 5 ohms?

PINPOINT TEST C: THE ENGINE CRANKS SLOWLY

Test Step Result / Action to Take
NOTE: Before beginning this test, be sure that the battery is tested and fully charged.
C1 CHECK THE VOLTAGE TO THE STARTER Yes

GO to C2 .

No

REPAIR the circuit between the battery and the starter solenoid.

CLEAN and TIGHTEN the connections at the battery terminals.

TEST the system for normal operation.
  • Key in OFF position.
  • Measure the voltage between the starter motor solenoid positive terminal and ground.

  • Is the voltage 12.5 volts or greater?
C2 CHECK MOTOR GROUND CIRCUIT Yes

INSTALL a new starter motor.

REFER to Starter Motor-3.8L or Starter Motor-4.6L . TEST the system for normal operation.

No

REPAIR the ground circuit as necessary. TEST the system for normal operation.
  • Carry out the Motor Ground Circuit test; refer to Component Tests in this section.
  • Is the ground OK?

PINPOINT TEST D: UNUSUAL STARTER NOISE

Test Step Result / Action to Take
D1 CHECK THE STARTER MOTOR MOUNTING GO to D2 .

No

REINSTALL the starter motor correctly. REFER to Starter Motor-3.8L or Starter Motor-4.6L in this section.
  • Inspect the starter motor mounting brackets for cracks.
  • Check the starter motor mounting bolts for looseness.
  • Is the starter motor mounted correctly?
D2 INSPECT THE STARTER MOTOR Yes

INSTALL a new starter motor. REFER to Starter Motor-3.8L or Starter Motor-4.6L in this section.

TEST the system for normal operation.

No

CHECK the starter drive. REFER to Component Tests, Starter Drive Test in this section. INSTALL a new starter motor. TEST the system for normal operation.
  • Remove the starter motor; refer to Starter Motor-3.8L or Starter Motor-4.6L in this section.
  • Inspect the starter motor for damage.
  • Is the starter motor damaged?
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