starting Archives - UnderhoodService
Coil On Plug Ignition: The Wired Differences

For late-model vehicles, the norm is one ignition coil per cylinder, commonly known as coil on plug. The task of providing voltage potential to each spark plug is performed so reliably that it’s easy to take for granted.

VIDEO: Modern Starters And Diagnostic Hammering

Andrew Markel tackles the age-old diagnostic technique of hitting the starter with a hammer, and the obvious disadvantages to doing so on starters in modern vehicles. Sponsored by Denso.

VIDEO: Diagnosing The Starter With A Voltage Drop Test

Andrew Markel shows how to voltage drop test a starter when there is a slow crank, despite the battery and starter having enough voltage. Sponsored by Bosch Automotive Service Solutions.

AUDI: Start-Stop System Information

This informational TSB applies to Audi vehicles with a start/stop system. The start/stop system allows automatic engine stops and starts. Although the driver expects it, the engine may not automatically be switched off due to many different factors.

VIDEO: Stop-Start System Service Opportunities

Andrew Markel discusses service opportunities for vehicle stop-start systems and how several modules are involved in the activation of the feature. Sponsored by Bosch Automotive Service Solutions.

Fuel Pump Diagnostics: Using Scan Tools

The most common diagnostic procedures for fuel pumps in the past were analog and hands on. Most fuel pump-related problems could be solved with a pressure gauge and voltmeter. Today, the scan tool is the most important tool when diagnosing a fuel supply problem.

Using Your Oscilloscope: Current Ramp Test Ignition Coils

The diversity of modern ignition coil designs has made ignition oscilloscope analysis more difficult because many ignition coil waveforms deviate from the conventional norm. Consequently, oscilloscope diagnosis shouldn’t be considered a definitive test of ignition coil condition unless it can be compared with a known-good waveform.

ignition coil scope tip
Parasitic Drain: 2003 Chevrolet Tahoe

This month’s Diagnostic Dilemma concerns a 2003 Chevrolet Tahoe with a parasitic battery drain that leaves it with a dead battery. The first step in diagnosing a parasitic drain is interviewing the customer to determine the average number of days and the driving conditions under which the battery drains.

Throttle-By-Wire Codes: P1512 On 2002 GMC Envoy

The PCM continuously monitors the commanded and actual throttle positions. The commanded throttle position is compared to the actual throttle position based on accelerator pedal position and possibly other limiting factors, and both values should be within a calibrated range of the other.

GMC Envoy throttle by wire large
Acura: Intake Leak Code P2279 Set After Throttle Body Cleaning or Replacement

If you have just cleaned the throttle body and now you’ve a fluctuating idle and code P2279 (intake air system leak), the problem could be that the system needs to relearn the new throttle plate position because the system could be operating using the old data.

Secondary Ignition: The Art of Spark

What is a coil? From the beginning of the internal combustion engine, several different ignition systems have been used to create a high-energy spark. The most popular system, and the one that’s in use today, is a step-up coil. A coil is nothing more than a transformer, and like any transformer, it has two separate

secondary ignition
Origins of the ‘Bendix’ starter

Every now and then you will run into an old-timer who uses the term “Bendix” in reference to the starter. You may think brakes when you hear this term, but there is some interesting history behind “Bendix” being used to describe a starter. By 1910, Vincent Hugo Bendix was almost bankrupt after the failure of

Bendix starter