Heavy Duty Alternator

Tech Tip: Diagnosing starter cranking problems

While cranking problems can be frustrating, identifying and correcting the root cause does not have to be. The first step is to identify the symptoms. In a cranking system, you can divide your symptoms into one of two possible troubleshooting categories: 

  • Click or No Click: If you turn the key and no cranking of the engine occurs, you have what is known as a “click or no click” problem. Sometimes you may or may not hear a clicking noise when the key is turned.

  • Slow Cranking: This is present when you turn the key and you can hear the starter cranking the engine, but not fast enough to support an engine start.

Initial Troubleshooting Steps

Once you’ve identified which problem you’re dealing with, then you can start to remedy it. For both issues, the initial troubleshooting is the same.

  • Step 1: Begin at the batteries. As with all starting and charging system diagnostics, troubleshooting should begin only after the batteries are visually inspected, pass a load test and show to be at least at or above 12.3 -12.4 volts.

  • Step 2: Perform a voltage drop test on the starter main cables. This is an important step and is often the cause of a slow cranking complaint. But voltage drop in the main cables is also a leading cause of click or no click complaints because almost every vehicle manufacturer uses the heavy positive post located on the starter solenoid as a place to pick up the current used to supply the control circuit.

  • Step 3: Until now, the diagnostic path has remained the same regardless of the complaint. Now is where you address the specific issue.

    • Slow Cranking: Your troubleshooting is done. Remember, for the starter to be cranking, the control circuit would have to be working. If battery and cable checks are complete (and within specification) and the vehicle still cranks slowly, then it’s time to replace the starter.

    • Click or No Click: Check the control circuit. If the starter does not contain an Integrated Magnetic Switch (IMS) function, then a voltage drop test will need to be performed on the vehicle control circuit. If the starter does have an IMS switch function, then the technician will have to verify that the vehicle’s control circuit is providing voltage to the starter IMS. Just like the slow cranking complaint, if all systems have been checked, and the starter is found to be the cause, the ring gear should be inspected for damage that could cause future starter damage. 

Remember: Before attempting the procedures above, make sure you are aware of and practice all safety measures involved in working with batteries, electrical systems and rotating machinery. Always make sure the wheels are chocked and the vehicle is in park or neutral before attempting the diagnostics.

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