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 .

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 .

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 .

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.

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 .

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.

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.

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 .

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.

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.

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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