AutoInc. Magazine
   
MAGAZINE
Home
Current Issue
Ad Index
AutoInc. Archive
How to Contribute
Reprint Permission
RSS
READER SERVICES
Subscription Info
Letters to the Editor
ANNUAL FEATURES
Top 10 Web Sites
Software Guide
NACE Online Daily News
How's Your Business?
ADVERTISING
Ad Opporunities
Media Planner
ABOUT AUTOINC.
AutoInc. Mission
Meet Our Staff
  Tech Tips

Hotline Archive Helps Fix F-250

Posted 8/13/2009
By Jeff Boskowitz

Occasionally you run across one of those extremely unusual complaints, one that no one ever remembers hearing. Recently, I had just such a call.

The vehicle was a 1997 F-250 7.3L Power Stroke diesel with an E4OD transmission. The complaint was no torque converter clutch (TCC) lockup, and the technician said there was never a code stored in the powertrain control module (PCM).

"The vehicle was a 1997 F-250 7.3L Power Stroke diesel with an E4OD transmission. The complaint was no torque converter clutch (TCC) lockup, and the technician said there was never a code stored in the powertrain control module (PCM). "

This vehicle ran flawlessly. The transmission had been rebuilt 50,000 miles prior to this, and again recently, to try to cure the TCC concern. The tech had tried clearing codes and rechecking operation, in case it was a scanner issue. The PCM had been replaced twice, and the solenoid pack and subharness had been replaced as well. He also verified that the stop lamps worked and that the correct bulbs were installed.

I asked him to start the diagnosis by checking for battery voltage through the TCC solenoid on the purple/yellow wire at pin 28 of the PCM, with key on, engine off (KOEO). With voltage present, I asked him to shut off the key, disconnect the PCM connector and check for correct solenoid and circuit resistance of 20 to 30 ohms. That was OK, so I recommended that he road test the vehicle with a labscope connected to pin 28 to see if the PCM ever attempted to ground the circuit. It did not, so the next step was to physically ground the wire while driving to see if lockup could be achieved. It did go into lockup, so the next step was to check for excessive current flow through the solenoid during activation, which could damage the PCM driver. Based on the TCC circuit resistance, I expected a reading of 0.4 to 0.6 amps - it was 0.51 amps. Everything was pointing to a faulty PCM. Ford's flowcharts led us nowhere.

Then, for some reason, my "senior moment" started to subside. Something sounded familiar, so I logged onto Identifix Direct-Hit and searched - using "Keyword TCC" for "Models w/same engine package +/- two years." It returned eight Hotline Archives. Amazingly, the second one, authored in August 2005 by - guess who - me (no wonder it sounded familiar) on another 1997 model, had the identical symptom.

On the sixth call, I had asked the tech the elevation of his shop, and he said it was approximately 1,000 feet. Next, I had him check the manifold absolute pressure (MAP) sensor frequency. This was reported to be 111.7 Hz, which confirmed his elevation. When I asked him to check the voltage of his barometric pressure (BARO) sensor while backprobing the dark blue/light green wire for between 4.4 and 4.6 volts at that elevation, the reading turned out to be 0.16 volts. It is likely that only the space shuttle could get a reading that low, so the sensor was replaced.

And so, with the help of that forgotten Hotline Archive from nearly three years ago, the current vehicle also now shifts perfectly. I am proof that no one can remember everything!
Jeff Boskowitz Jeff Boskowitz is an Identifix Ford carline specialist. He is certified in Ford EEC I-V, 7.3L and 6.0L powerstroke diesel. He is ASE master and L1 certified.
Experience Identifix This information is provided by IDENTIFIX®. IDENTIFIX® resources cut diagnostic time and provide repair solutions that increase the shop's bottom line. From Repair-Trac pattern failure quick fixes, to Diagram-Online wiring diagrams by fax, to the Repair Hotline staffed by 32 master techs who specialize in diagnosing complex problems by phone or fax, IDENTIFIX® helps techicians fix more cars in less time.

For more information on IDENTIFIX, call (800) 288-6210, 8 a.m. - 6 p.m. Central Time.

www.identifix.com.

© 2011 IDENTIFIX. All Rights Reserved.

MOST ACCESSED ARTICLES

  • Fuel Injection Service, Not Just Cleaning
  • The Art of Extraction
  • EGR Systems: Operation and Diagnosis
  • Proactive Target Marketing:_Rethinking Your Business Strategy
  • Engine Performance: HO2S Diagnostics
  • MOST E-MAILED ARTICLES

  • Developing Employee Potential
  • How Critical Thinking Can Help Your Business
  • How to Diagnose the Ford Glow Plug
  • What to Look for When Shopping for the Right Shop Management Software
  • Putting a Price Tag on Complaints
  • AutoInc. Web Site | ASA Web Site | NCOIL Reviews Model Airbag, Parts Legislation | The Day After Training ... Now What? | Tech to Tech | Tech Tips | News Briefs | Taking the Hill | Around ASA | Shop Profile | Net Worth | Stat Corner | Members' Advantage | Guest Editorial | Chairman's Message

     
    Copyright (c) 1996-2011. Automotive Service Association®. All rights reserved.
    XML Add RSS headlines.