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Strange Requests At The Service Counter

Sometimes, I have to wonder if certain ­customers’ brains are firing on all cylinders. But as an automotive service professional, I have to maintain a certain level of self-control while answering their questions, even though what they’re...

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Are All Cars ‘Supercars’ Now?

I attended an open house at Smokey’s Dyno in Akron, Ohio, last month. The shop was filled with Lamborghinis, Jaguars and other high-end cars. It was a great chance to look under the hoods of some supercars. The shop even had a rare McLaren P1 sitting...

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Documenting Inspections: Are You Leaving Maintenance Dollars on the Table?

How do you translate scribbles on a ­repair order into sales? There is no magic trick involved — the key is to document the vehicle ­inspection process. The more you know about your customers’ vehicles, and the more you are able to document...

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Mazda: Performing Regular Undercar Maintenance

This month, we’ll take a look at brake and undercar service on the Mazda vehicle lineup, with the footnote that even though this type of work ­becomes routine when you have a preventive maintenance mindset, good work habits from beginning to end are...

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Import Automatic Transmission Diagnostics

Don’t be alarmed if you pull an automatic transmission trouble code when diagnosing a “check engine” warning light! Since the automatic transmission operation has a major effect on grams-per-mile exhaust emissions, you’re going to see the...

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Honda: Vehicle Won’t Move or Barely Moves

A customer brings in a vehicle that won’t move forward, ­­backward or both. Check first to see if it grinds or clicks. And does the speedometer read a lot higher than you’re actually going? Chances are the driveshaft is disengaged. This can...

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TPMS Service Tip: Ask the Right Questions

If there is one piece of major advice for any tire tech facing a TPMS issue, it would be this: Test before you touch, and document the answers you get. Understanding the potential TPMS land mines can save time and money and eliminate frustrations. Get...

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False ABS Activation After Wheel Bearing Hub Replacement

Vehicles: All ABS-equipped vehicles Condition: Vehicle had wheel bearing hub replaced on one side. Repair Procedure: If you diagnose a bad hub bearing on one side of a vehicle and the ABS wheel speed sensor or tone ring is integral to the bearing,...

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Are you afraid of selling alignments?

I am starting to notice a trend when it comes to alignments. It’s not the vehicles that are changing, but rather the attitudes toward alignment services — and it happens at independent repair shops, franchise shops and even dealers. The alignment...

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iATN Exceeds 2 Million Forum Messages

The number of messages in the professional automotive discussion forums of the International Automotive Technicians Network (iATN) exceeded 2 million in early December 2014, with the Shop Management and Technical Discussion forums being the most popular...

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Diagnosing Starter Misses

Contributing writer Gary Goms was called to a friend’s shop to help with a no-cranking condition on a 2006 Chevy Tahoe. After diagnosing a faulty PCM ground, locating the missing ground proved to be problematic. Find out how Gary solves The Case...

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Snap-on Adds Diagnostic Calculator To Website

Snap-on announces a new diagnostic calculator feature has been added to its website at http://diagnostics.snapon.com to help automotive repair technicians and shop owners determine how much profit they could be making by using a Snap-on diagnostic platform,...

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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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