Common Starting Issues in Trucking Applications---Part 1

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 three possible troubleshooting categories:

Slow Crank: The Mitsubishi starter will crank, however, the engine RPM is too slow to start the vehicle.

Click No-Crank: The solenoid clicks but the starter doesn’t crank.

No-Click No-Crank: The solenoid doesn’t click and the starter doesn’t crank.
Once you’ve identified which problem you’re dealing with, then you can start to remedy it. For all issues, the initial troubleshooting is the same: you start with the batteries.

STEP 1 – Begin at the batteries: Charge the batteries and perform a load test on each battery in the battery bank. If any batteries aren’t up to spec they need to be replaced or you will shorten the life of the other batteries and compromise the health of the starting circuit.

STEP 2 – Perform a voltage drop test: Once the batteries pass your tests, perform a voltage drop test on the starter main cables. The starter voltage drop should be less than .5V total on the cranking circuit. This is an important step and is often the cause of a slow cranking complaint. Yet voltage drop also is 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 – Identify the specific issue: Until now, the diagnostic path has remained the same regardless of the complaint. Now is where you address the specific issue.

Tips from: www.dieselnews.com.au