Diagnostics Archives - Page 8 of 39 - TechShop Magazine
Using an Oscilloscope to Diagnose DTCs

When our writers found that the P2716 Pressure Control Solenoid “D” Circuit DTC was common on Toyota Corollas, they decided to share their diagnostic journey with our readers.

Pulling Codes: Multiple Misfire Personalities

A vehicle fails an emission test due to a series of codes, with misfire activity found on cylinders 2, 4, 6, 8 and 3 – and a strange metallic sound can be heard when the rpms are raised. See how Carlton Banks solves this latest Pulling Codes case.

Easily View Hard-to-Reach Areas with Launch Videoscope

With the Launch Videoscope/Borescope’s fluid-resistant 7mm head, LED illumination and side-view angle mirrors, dark, fluid-soaked and hard-to-reach areas are no problem. View and record video in full VGA resolution at 30 frames per second. Take snapshots and save images right to your Launch scan tool.

Modern Fuel Control Diagnostics: Sorting Through the Datastream

When confronted with a fuel control problem, contributing writer Gary Goms normally uses short- and long-term fuel trims to determine if the problem is caused by one of many failures such as a vacuum leak or a leaking fuel pressure regulator. He says some aftermarket scan tools may display AFR sensor data in a confusing way, so he helps techs sort out this datastream maze.

Pulling Codes: P0302: Cylinder 2 Misfire Detected Intermittent Activity

This article addresses a misfire code from a 1999 VW Passat. It will look at a plan of attack for when a P0302-Cylinder No. 2 Misfire Activity Detected code is being set intermittently. While this code has been encountered by many, this particular failure was unique in that it allowed one to witness theory truly come to life.

Pinning Down Intermittent Malfunctions On OBD II Vehicles

Although post-1996 OBD II powertrain control modules (PCMs) are generally very reliable, we’re beginning to see more failures because the average age of our national vehicle fleet has now increased to about 11.5 years. Technically speaking, the PCM should store a DTC indicating some type of internal malfunction. But, in the real world, if your scan tool indicates “no communication” and asks if the ignition switch has been turned on, you obviously have a communications problem.

The Cracked Plate Coincidence: Uncovering An Uncommon Flex Plate Issue Twice In One Week

It never ceases to amaze me when I see certain types of problems in rapid succession of one another and then not see them again for months or even years. This column is dedicated to one such occurrence. Within a week of each other, two different vehicles came into my shop with cracked flex plates. While I have seen flex plates crack throughout my career, it is not a common scenario.

Don’t Judge A Job By Its Cover

It was a picture perfect day at the auto repair shop until two new jobs showed up at the same time. A nice, clean 2007 Ford F-350 4WD diesel with an ABS light on, and a really dilapidated 1997 KIA with charging system problems and no light on. You’ll never guess how these two stories end.

Snap Test: MAF Sensor Diagnostics

You’d think a service light would be the first indicator of a mass air flow (MAF) sensor problem, but there are times a problem develops with the MAF and no service light comes on. Scott “Gonzo” Weaver explains how poor idle, loss of performance, sluggish performance and even stalling are all associated with a failing MAF sensor.

Diagnosing Variable Valve Timing

Fully variable valve timing can be achieved only by using computer-operated solenoids to precisely control the intake and exhaust valve opening and closing events. Although the various combinations of valve timing events are theoretically infinite on an electronically controlled system, their applications are limited due to issues of cost and, in some cases, reliability.

Tooling Up For The Diagnostic Process

Automotive trainer John Forro advocates knowing your tooling needs and developing a strong relationship with those tools. Knowing a tool’s capabilities and limitations will help you advance your diagnostic process.

Nissan Diagnostics: Check Engine Light And Misfire Issues

The late-model Nissans have proven to be quite reliable when it comes to serial-type problems that would get them to your bay with check engine lamp issues. Nissan has done a good job of addressing some of the problems we’ve looked at in the past. But that doesn’t mean you won’t be seeing Nissans looking for attention, and that spells service opportunities for you.