Auto Service World
Feature   December 1, 2004   by Auto Service World

Countertalk: Reducing Electronics Comebacks

While some tech-nicians struggle to climb the learning curve that a new generation of electronics requires, there is little doubt that this will mean added stress for counterpeople, and the need to revisit goodwill warranty issues time and time again.

Certainly, it is advisable for everyone involved with the trade customer to reinforce the need for training, and offer courses whenever possible. This has proven to be a key to reducing comebacks whenever new vehicle systems have emerged.

A second key point is to ensure that the shop in question has at least the minimum equipment required to perform top-level diagnostics at the very least. It is much more preferable for shops to be fully capable of using the best diagnostic scan tools out there–dedicated tools like the Tech Flash II–but economics can make this difficult.

A four-pronged set of tools can keep misdiagnosis to a minimum:

1. Understanding computer control operation (open loop, closed loop, input, output.)

2. Service manuals or reference materials as specific as possible for the vehicle.

3. A scan tool that can read diagnostic codes and the data stream from that vehicle.

4. A Digital Volt Ohm Meter (DVOM) to test circuit integrity and measure the amp draw on output devices.

While it is not unheard-of for even the OEM to suggest substituting a known good unit to determine if there is a problem with an ECU, good technicians should be able to determine with a fair degree of certainty whether it is an ECU failure causing a car’s woes, or if it is something else.

There are a few things that you can do, however, to keep the trial and error approach from depleting your shelves of good units.

One of the most effective is to continually reinforce the fact that electronics are subject to a different set of rules than traditional hard parts when it comes to warranty and the return of units. While you should be fully briefed on the specific warranty handling policies of your suppliers, you should be mindful not to scare a customer off to the car dealer in doing so.

Nonetheless, you can suggest that all technicians follow a simple, general diagnostic procedure:

Techs should perform a voltage check, at the battery and with the engine running. The reading should be between 13.8 and 14.2 volts. A reading outside this range, either too high or too low, can cause myriad computer control issues and may even lead to component damage.

It is always a good idea to ensure that this voltage is reaching the ECU and other components, by cleaning the ground terminals at the ECU and the battery terminals.

Performing a reference voltage check at the sensors is an important way to eliminate some issues. This is usually 5 volts.

Obviously, open circuits or shorts in the sensor ground circuit at the ECU will affect its ability to control systems, so techs should probe for these.

Diagnostic trouble codes can be a real boon to technicians, but only if they have the right tools and knowledge to put them to use. Any DTCs that crop up must be rectified.

Also, just to be on the safe side, any output devices need to be tested for proper resistance and current draw.

Naturally, anything a tech can do to eliminate other problems–perhaps by using a detailed diagnostic tree–will only make his life easier in the long run. And yours, too.

Special thanks to Blue Streak Electronics, Cardone Industries and Crown Remanufacturing for information used here.

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