Mercedes: Addressing MIL Issues
‘Systems Operation’ Knowledge and Proper Equipment Saves Diagnostic Time and Speeds Repair Process It may not be a Mother-in-Law light, but the effect can be about the same. Just when you don’t want to see it, there it is! The Malfunction Indicator Light (MIL) has been around for more than 25 years, but since OBD
P0401 Codes and EGR Issues
As emission controls got tighter, and with the advent of OBD II, things started to change. We not only saw additional driveability complaints, but we also had the check engine light (CEL) telling the customer there was an emissions failure that had to be dealt with for the good of the environment and, in most
Time and a Half
One of the hot-button issues in the independent automotive service industry is how to charge for diagnostic time. Currently, the debate is framed by two basic schools of thought. The practitioners of the first school are the shop managers who regard “free diagnostic code reads” as a marketing expense needed to lure potential customers into
Current Trends for Ignition Systems
As automotive technology moves forward, ignition systems are becoming more and more entangled with other systems on the engine. The current generation Nissan Maxima 3.5L V6, which was introduced in 2004, has a fairly conventional coil-on-plug (COP) ignition system. The individual coils are driven by the powertrain control module (PCM) using the input signal from
Replacing Hubs with Wheel Speed Sensors
By Larry Carley, Technical Editor When engineers came up with the idea of putting the wheel speed sensor (WSS) and tone ring inside a sealed wheel bearing hub assembly, it seemed like a great idea. The sealed environment would help protect the sensor and make it less vulnerable to damage or contamination from the outside
Tech Feature: Engine Diagnostics…What to do When an Engine Won’t Start
In today’s world of high-tech electronics, onboard diagnostics and scan tools, you would think engine diagnostics would be easier than ever. Yet some technicians struggle when confronted with an engine that cranks but refuses to start. Most no-starts do not generate any fault codes, so how do you proceed to find out what’s causing the
Diagnostic Dilemmas: Got a Light?
Every diagnostic technician experiences operational complaints that are more bizarre than they are technically complex. The problem is made difficult when the technician fails to stand back from the problem and look at what I call, “The Big Picture.” As you will see in the following case study, The Big Picture is a collection of
Diagnostic Solutions: COP Ignition Systems
For a number of reasons, the trend of modern engine management technology is leaning toward using coil-on-plug (COP) ignition systems. One reason is that COP ignitions are very compact and are very adaptable to individual cylinder tuning. With the exception of a few designs that incorporate a driver or “module” into the COP assembly itself,
Decoding the Past
“I’d like for you to hook it up to the code machine and see what it says to replace” – anonymous customer Sound about right? It sure does. Of course, as auto repair professionals, we know better. We know that reading the code is not diagnostics, but rather that is where diagnostics might begin. We
Automatic Transmissions: From Mechanical to Electronic to Hybrid
A long time ago in a service bay, preventive maintenance for an automatic transmission was an oil change, band and throttle linkage adjustment. The 1960s saw the end of external band adjustments. In the 1970s, the drain plug went away and the pick up screen was replaced with a filter. In the 1980s, a turbo
Oxygen Sensors: Pulse Measurement
Watching an oxygen sensor output on an oscilloscope is like watching a sporting event on television. You get to see the action, but can do nothing about it as it happens. Sometimes you miss the action and want an instant replay. It was a bad call. You saw the interference. If the referee didn’t see
Diagnostic Solutions: Cylinder Head Service, Restoring the Engine to Precise OE Tolerances
Although cylinder head repairs have been a staple of the import repair shop for many years, modern technology has changed the way we should sell and perform cylinder head services. In years past, for example, a cylinder head repair need last only 30,000 or 40,000 miles until the vehicle was retired from service. Today, however,