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Victoria Car Battery & Electrical System Maintenance - Multimeter Testing



You can use a multimeter to check for starter problems. A multimeter can check voltage, amperage and resistance using a single device. Also called a digital multimeter (DMM) which displays exact numeric values rather than moving a needle on a dial.

To test the starter, to see if it needs replacement, measure the amperage on the battery-to-starter cable while cranking the engine. Typically, the starter should draw about one ampere per cubic inch of engine displacement, plus or minus about 25-percent (check the service manual for details of your particular vehicle)

If the measured current is not too high, measure the resistance. Starter current can be over 200A or 300A on large displacement engines, so even low resistance can cause a significant voltage drop. A drop of only 0.2 to 0.3 volts can reduce automotive performance. Set the DMM to the millivolt scale, connect the positive lead to the side of the component nearest the battery (+), and the negative lead to various points including the connecting cable, the solenoid posts, and wires that attach to them. and across the solenoid itself. Also, check connections to the starter, alternator and ground strap link the engine block and body.

Normal Voltage Drops

Across wires or cables

200 mV

Across switches

300 mV

Grounds

100 mV

Connectors

0 mV


If the battery cables are damaged or have worn insulation, replace them. Spend a few extra bucks and get the best quality ones. Cheap ones typically have small gauge wire covered by thick insulation, but cannot carry the peak current when needed.

A "click" with no cranking probably means the solenoid is being energized but there is not enough current to turn the starter over. Test for a faulty solenoid by bypassing it, and seeing if the starter now spins.

If the starter spins, but it will not crank the engine, check for an engagement problem. The latter could be caused by a weak solenoid, defective starter drive or broken teeth on the flywheel. A starter on the verge of failure may engage, but slip. Incidentally, if the starter locks ups while engaged with the flywheel, it can over rev the starter destroying it.

Listen for unusual noises from by the starter system. A high pitch whine could be a mis-aligned starter. Also, tighten any loose nuts & bolts.

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