Maintaining the battery, battery cables and starting system
There’s nothing worse than being in a hurry to get somewhere and the car won’t start. Nothing. Simple routine maintenance like checking your battery and cables at certain intervals can be the difference between a good start and your vehicle not starting at all.
THE STARTING SYSTEM
The basic starting system consists of the starter relay and the starter motor, with its integral starter solenoid. But there are other components that are considered to be part of the starting system. These include the battery, battery cables, ignition switch, the position switch (clutch pedal or park/neutral depending on the type of transmission), and the wire harness and connectors.
When a vehicle does not start, the problem can usually be traced to the starter relay, starter motor or the battery. The ignition switch and position switch are not usually at fault. When a vehicle does not start, what is the first component that you check? It’s probably the battery. If there’s no juice, there’s no starting the car, regardless of the condition of the other starting system components.
The battery, starting and charging systems operate in conjunction with one another and should be tested as a complete system. When attempting to diagnose a problem with any of these systems, it is important to remember the interdependency of these systems.
The diagnostic procedures used include the most basic conventional diagnostic methods to the more sophisticated on-board diagnostics (OBD) built into the powertrain control modue (PCM). Tools such as an induction-type milliampere ammeter, volt/ohmmeter, battery charger and 12-volt test lamp might be required.
BATTERY INSPECTION AND TESTING
The battery is the key to the starting system. The following details are the recommended inspection procedures for the battery and related components. In addition to the maintenance schedules found in this service manual and the owner’s manual, it is recommended that these procedures be performed any time the battery or related components must be removed for vehicle service.
- Inspect the battery cable terminal clamps for damage; replace any battery cable that has a damaged or deformed terminal clamp.
- Inspect the battery tray and battery hold down hardware for damage.
- Inspect the battery case for cracks or other damage that could result in electrolyte leaks. Also, check the battery terminal posts for looseness; batteries with damaged cases or loose terminal posts must be replaced.
- Inspect the battery thermal guard for tears, cracks, deformation or other damage.
- Inspect the battery’s built-in test indicator sight glass (if equipped) for an indication of the battery condition.
The Midtronics GR8 battery system tester is designed to help diagnose the cause of a defective battery. This device is an excellent tool for checking the state of a battery. Remember, batteries have a specific service life. If your customer is trying to get a 4th or 5th year out of a battery, advise them to replace it.
If your shop does not have a battery system tester, there are still tests you can perform that will indicate the condition of the battery. A very common test is the battery open-circuit voltage (no load) test. This test will indicate the approximate state-of-charge.
First, remove the surface charge by turning on the headlamps for 15 seconds. Next, allow the voltage to stabilize for 5 minutes. Then, disconnect the battery cables (negative first) and connect the voltmeter. A reading of 12.4 volts or more indicates adequate charge.
INSPECTING AND TESTING BATTERY CABLES
Battery cables can be a big source of problems. A voltage drop test will determine if there is excessive resistance in the battery cable terminal connections or the battery cable. If excessive resistance is found, the connection point should be disassembled, cleaned of all corrosion or foreign material, then reassembled. After reassembly, check the voltage drop for the battery cable connection and the battery cable again in confirm repair.
Before performing the voltage drop test, inspect the cables. Corrosion can be a major problem, especially on older vehicles (more than 10 years old). Refer to Figure on the left. Notice the heavy corrosion. This corrosion works its way down the wire inside the cable sheath. Instead of doing a voltage drop test on this cable, it’s better to just replace it. End of problem.
When performing the voltage drop test, 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.
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 terminal clamp. Rotate and hold the ignition switch in the Start position. Observe the voltmeter. If voltage is detected, correct the poor connection between the battery negative cable terminal clamp and the battery negative terminal post. Repeat this test using the battery positive terminal post and the battery positive cable terminal clamp.
Check the voltage drop between the battery and starter. Refer to Figure on the right. Connect the voltmeter (2) to measure between the battery positive cable terminal clamp (1) and the starter solenoid B(+) terminal stud (3). 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 positive cable eyelet terminal connection at the starter solenoid B(+) terminal stud. Repeat the test. If the reading is still above 0.2 volt, replace the faulty battery positive cable.
Connect the voltmeter (1) to measure between the battery (2) negative cable terminal clamp and a good clean ground on the engine block (3). 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 eyelet terminal connection to the engine block. Repeat the test. If the reading is still above 0.2 volt, replace the faulty battery negative cable.
There’s a good chance that most starting problems are the result of the battery or the battery cables. So, check them often and put an end to the start that never happens.