Starting system

DIAGNOSIS

The battery, starting, and charging systems operate with one another, and must be tested as a complete system. In order for the vehicle to start and charge properly, all of the components involved in these systems must perform within specifications.

Group 8A covers the Battery, Group 8B covers the Starting Systems, and Group 8C covers the Charging System. We have separated these systems to make it easier to locate the information you are seeking within this Service Manual. However, when attempting to diagnose any of these systems, it is important that you keep their interdependency in mind.

The diagnostic procedures used in these groups include the most basic conventional diagnostic methods, to the more sophisticated On-Board Diagnostics (OBD) built into the Powertrain Control Module (PCM). Use of an induction-type milliampere ammeter, volt/ohmmeter, battery charger, carbon pile rheostat (load tester), and 12-volt test lamp may be required.

All OBD-sensed systems are monitored by the PCM. Each monitored circuit is assigned a Diagnostic Trouble Code (DTC). The PCM will store a DTC in electronic memory for any failure it detects. Refer to On-Board Diagnostic Test For Charging System in the Diagnosis and Testing section of Group 8C - Charging System for more information.

INSPECTION

For complete circuit diagrams, refer to Starting System in the Contents of Group 8W - Wiring Diagrams.

Before removing any unit from the starting system for repair or diagnosis, perform the following inspections:

WARNING: ON VEHICLES EQUIPPED WITH AIRBAGS, REFER TO GROUP 8M - PASSIVE RESTRAINT SYSTEMS BEFORE ATTEMPTING ANY STEERING WHEEL, STEERING COLUMN, OR INSTRUMENT PANEL COMPONENT DIAGNOSIS OR SERVICE. FAILURE TO TAKE THE PROPER PRECAUTIONS COULD RESULT IN ACCIDENTAL AIRBAG DEPLOYMENT AND POSSIBLE PERSONAL INJURY.

• Battery - Visually inspect the battery for indications of physical damage and loose or corroded cable connections. Determine the state-of-charge and cranking capacity of the battery. Charge or replace the battery, if required. Refer to Battery in the proper section of Group 8A - Battery for complete service information for the battery.
• Ignition Switch - Visually inspect the ignition switch for indications of physical damage and loose or corroded wire harness connections. Refer to Ignition Switch and Key Lock Cylinder in the proper section of Group 8D - Ignition System for complete service information for the ignition switch.
• Park/Neutral Position Switch - Visually inspect the park/neutral position switch for indications of physical damage and loose or corroded wire harness connections. Refer to Park/Neutral Position Switch in the proper section of Group 21 - Transmission for complete service information for the park/neutral position switch.
• Starter Relay - Visually inspect the starter relay for indications of physical damage and loose or corroded wire harness connections.
• Starter Motor - Visually inspect the starter motor for indications of physical damage and loose or corroded wire harness connections.
• Starter Solenoid - Visually inspect the starter solenoid for indications of physical damage and loose or corroded wire harness connections.
• Wiring - Visually inspect the wire harnesses for damage. Repair or replace any faulty wiring, as required. Refer to the proper section of Group 8W - Wiring Diagrams for complete service information and circuit diagrams for the starting system wiring components.

TESTING

COLD CRANKING TEST

For complete circuit diagrams, refer to Starting System in the Contents of Group 8W - Wiring Diagrams.

The battery must be fully-charged and loadtested before proceeding. Refer to Battery in the Diagnosis and Testing section of Group 8A - Battery for the procedures.

(1) Connect a suitable volt-ampere tester to the battery terminals (Fig. 1). See the instructions provided by the manufacturer of the volt-ampere tester being used.

Fig. 1 Volts-Amps Tester Connections - Typical

1 - POSITIVE CLAMP

2 - NEGATIVE CLAMP

3 - INDUCTION AMMETER CLAMP

(2) Fully engage the parking brake.

(3) Place the automatic transmission gearshift selector lever in the Park position.

(4) Verify that all lamps and accessories are turned off.

(5) To prevent the engine from starting, remove the Automatic ShutDown (ASD) relay. The ASD relay is located in the Power Distribution Center (PDC), in the engine compartment. Refer to the fuse and relay layout label affixed to the underside of the PDC cover for ASD relay identification and location.

(6) Rotate and hold the ignition switch in the Start position. Note the cranking voltage and current (amperage) draw readings shown on the volt-ampere tester.

(a) If the voltage reads below 9.6 volts, refer to Starter Motor in the Diagnosis and Testing section of this group. If the starter motor is OK, refer to Engine Diagnosis in the Diagnosis and Testing section of Group 9 - Engine for further testing of the engine. If the starter motor is not OK, replace the faulty starter motor.

(b) If the voltage reads above 9.6 volts and the current (amperage) draw reads below specifications, refer to Feed Circuit Test in this section.

(c) If the voltage reads 12.5 volts or greater and the starter motor does not turn, refer to Control Circuit Testing in this section.

(d) If the voltage reads 12.5 volts or greater and the starter motor turns very slowly, refer to Feed Circuit Test in this section.

NOTE: A cold engine will increase the starter current (amperage) draw reading, and reduce the battery voltage reading.

FEED CIRCUIT TEST

The starter feed circuit test (voltage drop method) will determine if there is excessive resistance in the high-amperage feed circuit. For complete circuit diagrams, refer to Starting System in the Contents of Group 8W - Wiring Diagrams.

When performing these tests, it is important to remember that the voltage drop is giving an indication of the resistance between the two points at which the voltmeter probes are attached.

Example: When testing the resistance of the battery positive cable, touch the voltmeter leads to the battery positive cable clamp and the cable connector at the starter solenoid. If you probe the battery positive terminal post and the cable connector at the starter solenoid, you are reading the combined voltage drop in the battery positive cable clamp-to-terminal post connection and the battery positive cable.

The following operation will require a voltmeter accurate to 1/10 (0.10) volt. Before performing the tests, be certain that the following procedures are accomplished:

• Battery is fully-charged and load-tested. Refer to Battery in the Diagnosis and Testing section of Group 8A - Battery for the procedures.
• Fully engage the parking brake.
• Place the automatic transmission gearshift selector lever in the Park position.
• Verify that all lamps and accessories are turned off.
• To prevent the engine from starting, remove the Automatic ShutDown (ASD) relay. The ASD relay is located in the Power Distribution Center (PDC), in the engine compartment. Refer to the fuse and relay layout label affixed to the underside of the PDC cover for ASD relay identification and location.

(1) Connect the positive lead of the voltmeter to the battery negative terminal post. Connect the negative lead of the voltmeter to the battery negative cable clamp (Fig. 2). Rotate and hold the ignition switch in the Start position. Observe the voltmeter. If voltage is detected, correct the poor contact between the cable clamp and the terminal post.

Fig. 2 Test Battery Negative Connection Resistance - Typical

1 - VOLTMETER

2 - BATTERY

(2) Connect the positive lead of the voltmeter to the battery positive terminal post. Connect the negative lead of the voltmeter to the battery positive cable clamp (Fig. 3). Rotate and hold the ignition switch in the Start position. Observe the voltmeter. If voltage is detected, correct the poor contact between the cable clamp and the terminal post.

Fig. 3 Test Battery Positive Connection Resistance - Typical

1 - VOLTMETER

2 - BATTERY

(3) Connect the voltmeter to measure between the battery positive terminal post and the starter solenoid battery terminal stud (Fig. 4). Rotate and hold the ignition switch in the Start position. Observe the voltmeter. If the reading is above 0.2 volt, clean and tighten the battery cable connection at the solenoid.

Repeat the test. If the reading is still above 0.2 volt, replace the faulty battery positive cable.

Fig. 4 Test Battery Positive Cable Resistance - Typical

1 - BATTERY

2 - VOLTMETER

3 - STARTER MOTOR

(4) Connect the voltmeter to measure between the battery negative terminal post and a good clean ground on the engine block (Fig. 5). Rotate and hold the ignition switch in the Start position. Observe the voltmeter. If the reading is above 0.2 volt, clean and tighten the battery negative cable attachment on the engine block. Repeat the test. If the reading is still above 0.2 volt, replace the faulty battery negative cable.

Fig. 5 Test Ground Circuit Resistance - Typical

1 - VOLTMETER

2 - BATTERY

3 - ENGINE GROUND

(5) Connect the positive lead of the voltmeter to the starter housing. Connect the negative lead of the voltmeter to the battery negative terminal post (Fig.

6). Rotate and hold the ignition switch in the Start position. Observe the voltmeter. If the reading is above 0.2 volt, correct the poor starter to engine block ground contact.

Fig. 6 Test Starter Ground - Typical

1 - STARTER MOTOR

2 - BATTERY

3 - VOLTMETER

If the resistance tests detect no feed circuit problems, refer to Starter Motor in the Diagnosis and Testing section of this group.

CONTROL CIRCUIT TESTING

The starter control circuit components should be tested in the order in which they are listed, as follows:

• Starter Relay - Refer to Starter Relay in the Diagnosis and Testing section of this group for the procedures.
• Starter Solenoid - Refer to Starter Motor in the Diagnosis and Testing section of this group for the procedures.
• Ignition Switch - Refer to Ignition Switch and Key Lock Cylinder in the Diagnosis and Testing section of Group 8D - Ignition System for the procedures.
• Park/Neutral Position Switch - Refer to Park/Neutral Position Switch in the Diagnosis and Testing section of Group 21 - Transmission for the procedures.
• Wire harnesses and connections - Refer to Starting System in the Contents of Group 8W - Wiring Diagrams for complete circuit diagrams.