Diagnosing and repairing diesel no-starts can be very profitable if you know what to look for. The rules have changed in the last few years so it pays to know what to expect on a newer diesel vehicle with a no-start condition.
In fact, the process is much like diagnosing a no-start condition on any other type of vehicle – begin by performing a good preliminary inspection to catch anything obvious, check for service bulletins, tips and programming updates, and then (using service information) develop a theory about what’s happening and observe and take measurements to prove your suspicions are indeed correct (and then fix the problem). Easy enough.
But as with any other system, it helps to know what you’re checking and what to watch for so you don’t waste diagnostic time or miss something obvious.
Diesel fuel control systems have changed drastically in the last few years (even among similar vehicles from the same manufacturer) so it’s really important to understand how the system works for the exact model, engine and year of vehicle you’re working on and not just have a general overview of a generic system. And there are actually two reasons to be so specific and precise.
|Accessories wired into systems that feed power to critical systems can cause no-start conditions.|
First, high-pressure diesel systems do indeed run at extremely high pressures so it’s important to know the oil and fuel pressures expected at each part of the system and to be ready to test them safely, without ending up in the hospital or maybe even worse.
Second, understanding why each diagnostic step in the procedure is performed and exactly what to look for while doing it can often be the difference between a quick, accurate diagnosis and a long, expensive drawn-out headache.
If you’re ready to take on the challenges, here are a few tips for quickly diagnosing no-start conditions on newer diesel vehicles. We’ve learned them the hard way so you won’t have to.