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 the appropriate wiring information.
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 Shut Down (ASD) relay. The relay is located in Totally Integrated Power Module (TIPM). Refer to the label on the TIPM cover for relay location.
| 1 - VOLTMETER |
| 2 - BATTERY |
- 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. 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.
1 - VOLTMETER 2 - BATTERY - Connect the positive lead of voltmeter to the positive battery terminal post. Connect the negative lead of voltmeter to the battery positive cable clamp. 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.
1 - BATTERY 2 - VOLTMETER 3 - STARTER MOTOR - Connect the voltmeter to measure between the battery positive terminal post and the starter solenoid battery terminal stud. 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.
1 - VOLTMETER 2 - BATTERY 3 - ENGINE GROUND - Connect the voltmeter to measure between negative battery terminal post and a good clean ground on the engine block. 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.
1 - STARTER MOTOR 2 - BATTERY 3 - VOLTMETER - Connect the positive lead of the voltmeter to the starter housing. Connect the negative lead of the voltmeter to the negative battery terminal post. 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.
- 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. Refer to DIAGNOSIS AND TESTING .