Group 30: Electrical system
Malfunctions
Manual fault tracing in bus cables Special tools: Multimeter ..................................................... 9812519 IMPORTANT! Cut the current with the main switch before the cables are disconnected. Use the multimeter to check the bus cables. The conductors in the bus cables should not be in contact with each other. Disconnect a bus cable at each end and measure the resistance between the pins to check this. The multimeter should show infinite resistance between each pin. If the resistance is less than infinite, there is a fault.
Measuring the engine cables Two types of measurement are done on the engine cable harness, both resistance measurement and voltage measurement. The measurements are done to ensure that no open circuits or short circuits occur. If there is an open circuit, the resistance is infinite, and if there is a short circuit, it is close to zero. The resistance values given in the workshop manual are approximate, and should be regarded as guidelines. NOTE! When resistance measurement is done, the engine should be stopped and system voltage should be cut off with the main switch. All resistance measurement is done at +20°C (68°F) and with a cold engine.
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