Component Tests and General Diagnostics

STANDARD STARTING SYSTEM

The battery, starting, and charging systems operate in conjunction with one another, and must be tested as a complete system. For correct starting/charging system operation, all of the components involved in these three systems must perform within specifications.






INSPECTION

For complete starter wiring circuit diagrams, Refer to the wiring information. Before removing any unit from the starting system for repair or diagnosis, perform the following inspections:

WARNING: On vehicles equipped with airbags, refer to passive restraint systems, before attempting any steering wheel, steering column, or instrument panel component diagnosis or service. Failure to follow these instructions may result in possible serious or fatal injury.

- Battery - Visually inspect the battery for indications of physical damage and loose or corroded cable connections. Determine state-of-charge and cranking capacity of battery. Charge or replace battery if required. Refer to Battery. Note: If equipped with a diesel engine, a dual battery system may be used, and both batteries must be inspected.
- 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.
- Park/Neutral Position Switch - If equipped with an automatic transmission, 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 21, Transmission.
- Starter Relay - The starter relay is located within the Totally Integrated Power Module (TIPM). Locations.
- Starter Motor - Visually inspect starter motor for indications of physical damage and loose or corroded wire harness connections.
- Starter Solenoid - Visually inspect starter solenoid for indications of physical damage and loose or corroded wire harness connections.
- Wiring - Visually inspect wire harnesses for damage. Repair or replace any faulty wiring, as required. Refer to Wiring Diagrams.

TESTING

COLD CRANKING TEST

NOTE: For complete starter wiring circuit diagrams, Refer to the wiring information. The battery must be fully-charged and load-tested before proceeding. Refer to Battery.










1. Connect volt-ampere tester (1) and (2) to battery terminals (Figure 1). See instructions provided by manufacturer of volt-ampere tester being used.
2. Fully engage the parking brake.
3. Automatic transmissions, place gearshift selector lever in the Park (P) position.
4. Verify all lamps and accessories are turned off.
5. To prevent a gasoline engine from starting, remove the Automatic ShutDown (ASD) relay. The relay is located in Totally Integrated Power Module (TIPM). Refer to label on the TIPM cover for relay location.

NOTE: Attempt to start engine a few times before proceeding with following step.

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

6. Rotate and hold the ignition switch in START position. Note the cranking voltage and current (amperage) draw readings shown on volt-ampere tester.
a. If the voltage reads below 7.2 volts, refer to Starter Motor in Diagnosis and Testing. If the starter motor is OK, refer to Engine Diagnosis for further testing of the engine. If the starter motor is not OK, replace the faulty starter motor.
b. If the voltage reads above 7.2 volts and current (amperage) draw reads below specifications, refer to Feed Circuit Test.
c. If the voltage reads 12.5 volts or greater and the starter motor does not turn, refer to Control Circuit Testing.
d. If the voltage reads 12.5 volts or greater and the starter motor turns very slowly, refer to Feed Circuit Test.

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 starter wiring circuit diagrams, refer to Wiring Diagrams.

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

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

The following operation requires a voltmeter accurate to 1/10 (0.10) volt. Before performing these tests, make sure the following procedures are accomplished:

- Battery is fully-charged and load-tested. Refer to Battery.
- Fully engage parking brake.
- Place gearshift selector lever in Park (P) position.
- Verify all lamps and accessories are turned off.
- To prevent a gasoline engine from starting, remove the Automatic ShutDown (ASD) relay. The relay is located in Totally Integrated Power Module (TIPM). Refer to label on the TIPM cover for relay location.










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










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










3. Connect the voltmeter to measure between the battery positive terminal post and the starter solenoid battery terminal stud (Figure 4). Rotate and hold the ignition switch in 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 positive battery cable.










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










5. Connect the positive lead of the voltmeter to the starter housing. Connect the negative lead of the voltmeter to the negative battery terminal post (Figure 6). Rotate and hold the ignition switch in START position. Observe the voltmeter. If the reading is above 0.2 volt, correct the poor starter to engine block ground contact.
6. If equipped with a dual battery system (certain diesel equipped models), connect the positive lead of voltmeter to the positive battery cable clamp on the battery located on the left side of vehicle. Connect the negative lead of voltmeter to the positive battery terminal post on the battery located on the right side of vehicle. Rotate and hold the ignition switch in START position. Observe the voltmeter. If the reading is above 0.2 volt, clean and tighten the battery cables at both batteries. Repeat the test. If the reading is still above 0.2 volt, replace the faulty positive battery cable.

If the resistance tests detect no feed circuit problems, .

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 The starter relay is located within the Totally Integrated Power Module (TIPM). Locations.
- Starter Solenoid - .
- Ignition Switch - Refer to Ignition Switch and Key Lock Cylinder
- Park/Neutral Position Switch - If equipped with an automatic transmission, refer to Park/Neutral Position Switch, Transmission.
- Clutch Interlock Switch - .
- Wire harnesses and connections - Refer to Wiring Diagrams.