Pinpoint Test B: Unusual Starter Noise

Starting System

Pinpoint Test

Pinpoint Test B: Unusual Starter Noise

Normal Operation

Under normal operation, voltage from the Battery Junction Box (BJB) is supplied to the ignition switch through circuit SBB09 (RD). When the ignition switch is placed in the START position, voltage is supplied through circuit CDC35 (BU/WH) to Smart Junction Box (SJB) fuse 21 (5A).

For automatic transmission equipped vehicles, voltage is supplied from SJB fuse 21 (5A) to the digital Transmission Range (TR) sensor through circuit CBP21 (BU/GY) and then to the starter relay coil through circuit CET 40 (GN/OG) and CBP21 (GN/OG). A ground is supplied through circuit CDC12 (YE) and the PCM.

For manual transmission equipped vehicles, voltage is supplied from SJB fuse 21 (5A) to the starter relay coil through circuit CBP21 (BU/GY) and CBP21 (GN/OG). A ground is supplied through circuit CDC12 (YE) and the PCM. The PCM will not supply ground to the starter relay coil unless the clutch is depressed, grounding the clutch pedal position bottom of travel input to the PCM on circuit CDC 36 (GN/BN).

When the starter relay coil is energized, the relay contacts close. This allows power to be supplied from BJB fuse 7 (30A) through circuit SBB07 (WH/RD) to the relay contacts. Power 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. It also closes the solenoid contacts allowing power directly from the battery to energize the starter motor to start the engine.

This pinpoint test is designed to diagnose the following:
- Starter motor
- Starter motor mounting
- Ring gear



PINPOINT TEST B: UNUSUAL STARTER NOISE

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B1 CHECK THE STARTER MOUNTING


- Inspect the starter mounting bolts and brackets for looseness.
- Is the starter motor mounted correctly?

Yes
GO to B2.

No
INSTALL the starter motor correctly. REFER to Starter Motor - 2.3L Service and Repair or Starter Motor - 4.0L Service and Repair. TEST the system for normal operation.

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B2 CHECK FOR ENGINE NOISE


- Ignition OFF.
- Connect a remote starter switch between the starter solenoid B- and S-terminals.




- Engage the starter motor and verify that the noise is due to the starter operation.
- Is the noise due to the starter motor engagement?

Yes
GO to B3.

No
REFER to Engine to continue the diagnosis.

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B3 CHECK FOR UNUSUAL WEAR


- Remove the starter motor. Refer to Starter Motor - 2.3L Service and Repair or Starter Motor - 4.0L Service and Repair.
- Inspect the ring gear for damaged or worn teeth.
- Is the noise due to ring gear tooth damage?

Yes
INSTALL a flexplate or flywheel. REFER to Engine for 2.3L engines or Engine for 4.0L engines.
EXAMINE the starter pinion teeth. If damaged, INSTALL a new starter motor. REFER to Starter Motor - 2.3L Service and Repair or Starter Motor - 4.0L Service and Repair. TEST the system for normal operation.

No
INSTALL a new starter motor. REFER to Starter Motor - 2.3L Service and Repair or Starter Motor - 4.0L Service and Repair. TEST the system for normal operation.

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