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The Problem With Living in the ‘Now’

I once had a shop manager who concentrated on the “now.” Every day was a mad dash to complete the jobs at hand. He wanted to know who was working on what, where the parts were and when everything would be done. He was constantly reacting to a customer’s...

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ASE G1: Drive Belt Inspection, Replacement

The ASE G1 Certification test contains 55 scored questions, plus 10 unscored ­research questions, that cover a range of skills and knowledge related to maintenance and light repairs in engine systems, automatic transmission/transaxle, manual drivetrain...

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Amateurs and Hacks Provide Job Security For Automotive Service Professionals

Two cars pull up in front of my shop. The drivers didn’t come in, but I heard the commotion from my office window. The boyfriend opens the hood of his girlfriend’s car. They both stare at the engine; she tells the boyfriend that she was supposed...

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Even for an experienced diagnostic technician, ­attempting to diagnose an intermittent misfire ­condition that occurs only under specific driving conditions can be a frustrating exercise. Let’s begin by getting the basics out of the way. As we know,...

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Honda: Easy Fix for Engine Noise

We often encounter engines that have a cold-start knock or ticking noise. In this case, the 3.5-L V6 engines installed in various Honda models can make a knocking or ticking noise at idle and only when warm. The cause of the problem is that the rocker...

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Why Alignment Angles Change

An alignment angle doesn’t change randomly. There is a cause-and-effect relationship between external and ­internal forces that can alter the geometry of a vehicle’s suspension. Having the alignment reading for only one angle on one corner is just...

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Using Recalls, TSBs as Brake Job Tools

You are getting ready to perform a brake job on a vehicle. While checking the torque specifications on the vehicle, you decide to hit the tab with TSBs and recalls. All of a sudden you are staring at a screen of brake recall notices and TSBs for that...

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Causes of Clutch Failure: Diagnosing Chatter

One of the most difficult clutch-related problems is chatter. Chatter is sometimes difficult to diagnose because it has many root causes, and some of them may not seem related at first. Chatter can be detected as a pulsing or a grabbing sensation that...

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Analyzing the Cylinder Pressure Waveform from a Running Engine, Part 3

By Vasyl Postolovskyi and Olle Gladso Contributing Writers and Instructors at Riverland Technical and Community College in Albert Lea, MN   In Part 1 of this Maximizing Tools series, we discussed an alternative approach to diagnosing an engine...

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Mac Tools Is Wrenching for a Cure

In support of Breast Cancer Awareness month, Mac Tools is featuring a variety of Wrenching For A Cure products available for purchase in the Flyer 11 through Nov. 2. Featured pink products include clothing, accessories, flashlights, pint glasses, and...

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5 Tool Storage Tips

  As a technician, you likely own thousands of dollars worth of tools and equipment, and require tool storage capacity to hold them all, along with carts and accessories to help move those tools around your work area. Here are a few items...

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Home Electrical Battery Tech Tip: Chevy Malibu Starts and Stalls

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Vehicles affected:
Chevrolet Malibu: 1997-’99 2.4L, 1997-2003 3.1L and 2004 Malibu 2.2L and 3.5L.

Symptom:
Vehicle will start and then stall. Security indicator on the dash is on. DTC P1626, P1630 and/or P1631.

Problem 1 of 3:
The Body Control Module (BCM) failed to recognize the signal from the ignition lock cylinder.

Test & Fix:
A scan tool should indicate a DTC P1626, P1630 or P1631 stored in the Powertrain Control Module (PCM). The flow chart for each code will direct a scan tool to be used to access BCM codes. This is the best way to perform diagnostics on this problem.

If using a scan tool that is not capable of retrieving BCM codes or viewing data, try the following procedure. Disconnect the wires from the ignition lock cylinder. Turn the ignition key to the Key On, Engine Off (KOEO) position. Using a voltmeter, check voltage on the white wire, at the BCM, to ground. The voltage should read 12 volts.

Then check the voltage on the yellow wire, at the BCM, to ground. This should read 5 volts. Next check the black wire, at the BCM, being sure there is a good ground on this wire.

If there is a loss of ground on the black wire or the voltage is missing on the white or yellow wires, check the power and ground for the BCM and the connections at the BCM. If powers, grounds and connections are OK, the BCM will need to be replaced.

Note: When you remove the BCM, first disconnect connector C3 before you disconnect the remaining connectors. When you re-install the BCM, connect connector C3 last. Connector C3 contains the BCM power and ground sources. If the voltages are correct, proceed to step 2.

Problem 2 of 3:
The ignition lock cylinder fails to change the voltage on the yellow wire.

Test & Fix:
With the ignition lock cylinder electrically reconnected, back-probe the yellow wire with the positive lead of the voltmeter and connect the negative lead to a known-good ground. Insert the ignition key in the lock cylinder, rotating the key to the start position, then release the key, allowing it to return to the KOEO position.

During the time the key was rotated to the start position then released to the KOEO position, the voltage on the yellow wire should change from 5 volts to a lower value. Because there are 10 different voltage values, we are unable to give a specific voltage value. However, what the voltmeter should indicate is a change in voltage value. If this change in voltage did not take place, replace the ignition lock cylinder. For the theft system relearn procedure, go to step 3.

Problem 3 of 3:
A component related to the theft system, BCM, PCM or ignition lock cylinder has been replaced and the password needs to be re-learned.

Test & Fix:
Password programming can be done using the following procedure:

1. Ensure the vehicle’s battery is fully charged.

2. Use a scan tool to clear any diagnostic trouble codes from the PCM and BCM.

3. Starting with the ignition switch in the Off position, momentarily crank the engine and leave the key in the Run position while observing the security indicator. In 10 minutes the security indicator should turn off. Rotate the key to the Off position for five seconds.

4. Repeat step 3 two more times.

5. The fourth time the engine is cranked, the engine should start and the BCM and PCM will have learned the new password.

6. Clear the BCM and PCM trouble codes again.

Courtesy of Identifix, Inc.

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