Strategies Archives - Page 2 of 5 - UnderhoodService
Random No-code Failures: Jeep Cherokee, Ford Crown Victoria

Random no-code failures can be the most frustrating problems to diagnose because the condition usually cant be duplicated in the shop and the “fix” often cannot be verified by test-driving. In this instance, I use the word “random” to describe a condition that might occur only once in two weeks. Sometimes I’ll find something suspicious

99 Jeep Cherokee no code failure
The Case of the Missing Starter

I was called last fall by a client who owns a heavy-duty diesel shop to diagnose a no-cranking condition on his father-in-law’s 2006 Chevrolet Tahoe. Because his work is mainly with heavy-duty trucks, my client knew he was lacking both in tooling and technical background when he didn’t hear the familiar click of a starter

Diagnostic Dilemmas
Scope Accessories You Can’t Live Without

If you’re buying a new scope or upgrading one you already own, here are some accessories that can make you more productive.

What to Look For When Buying a Scope

If you’re in the market for a new scope, Underhood Service Editor Andrew Markel has provided his recommendations on how you can get the most bang for your diagnostic dollar.

Start Solving Transmission Electronic Control Problems

Troubleshooting an automatic transmission can be one of the most intimidating diagnostic procedures at a shop. The first reaction is typically, “We don’t do that type of work.” But there is profit in performing drivetrain diagnostics and “in-the-car” repairs.

The Year In Ride Control TSBs: Tried And True Fixes Can Expedite The Diagnostic Process

2013 was a good year for ride control TSBs. Some TSBs were intended for very few vehicles on the road, but the solutions can be used to resolve the same problems on a wide variety of vehicles. Several of the TSBs over the next two pages can help to solve chronic problems that have plagued some

Relearn Procedures Require TPMS Tool

Most vehicles require some type of “stationary” relearn procedure to reset the TPMS system. This requires a TPMS tool to activate each of the tire pressure sensors in a specified sequence so the TPMS control module can relearn their new locations.

Air Ride: Compressor Diagnostics

On most modern vehicles, the compressor and air ride control unit are very intelligent components. Most communicate with the Body Control Module (BCM) on a high-speed serial data bus. These systems have malfunction indicator lights on the dash and require the use of a scan tool to diagnose the system.

Diagnosing Air Ride Systems

Air ride diagnostics is more than a spray bottle of soapy water. On today’s late-model vehicles, it requires a scan tool, meter and scope. Swapping components will only lead you down a diagnostic black hole that leads to an angry customer and parts supplier. Modern air ride systems have a compressor and a module to control the flow of air to the struts or shocks. Control modules can have as many as 10 valves. They can also have three or more sensors to measure the pressure.

Using Scan Tools To Diagnose Faulty Fuel Pumps

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.

Pulling Codes: The Importance Of Communication – No Code Analysis

For this month’s Pulling Codes case, we will attempt to provide a plan of attack for communication issues on General Motors products with the Class 2 Protocol. Our diagnostic journey begins with a 2004 Chevrolet Tahoe. This vehicle was tested at the EPA test facility in our area and it was determined that there is no communication with the PCM.