Quantcast
Jump to content


First The Basics - Diagnostics starts with powers and grounds NOT with parts and labor


Recommended Posts

Posted
First, The basics
 
 
tp.gif    Let’s talk diagnostics.  Do you follow any kind of diagnostic 
procedure, or do you just throw darts on a wall, or play 
“pick-a-part” and hope you fix it before you or the customer 
runs out of cash.  I hope you don’t do that.  That might work 
some of the time, but it’s not a good way to get to the source 
of problems quickly or accurately. 
 
 
tp.gif    One of the tire shops that I do business with dropped off a 
2003 F450 with a 7.3 diesel for me to look at. It’s one of 
their service trucks that died on the highway.  
 
 
    These guys are super, I’ve known them for years, and they’ve got a great reputation and excellent work force. In fact, I buy all my tires there, and they do all my alignments.  They try to fix their own trucks “in-house” and sometimes, well……the repair/diagnostics are a little out of their comfort zone.  This was one of those times. 
 
 
tp.gif    Now, they don’t try to keep up with the scanning or diagnostics on most cars and trucks. It’s a tire shop that specializes in tires.  They stick to what they do best, tires, wheels, and undercarriage stuff.  The only “techy” stuff they get into is with the TPM systems.  Most generally, when it comes to their vehicles they’ll go with the tried and true…”throw a dart and whatever it hits we’ll change.” Of course they’ll ask around first, but you know, second hand information hardly ever gets the job done these days.
 
 
tp.gif    They had it at one of their stores in another town for about 3 weeks trying to solve the problem.  When that didn’t work they decided to tow it up to another one of their stores, and see if the guys there had a better dart.  Another couple of weeks and several darts later, all they had were holes in the wall and no truck running.  Then my phone rang.
 
   “Can you program a PCM on a F450?” the shop asked.
    “No, sorry I don’t do those, but I know who does. I’ll call him and see if he can come over and do that for you,” I told them.
 
 
tp.gif    A day or two went by and the phone rang again.  “Hey, this thing still doesn’t start.  The guy that programmed it said it sounded like an electrical problem”.  Ok, somehow, I’m getting involved now.  
 
 
tp.gif“Sure, bring it over,” I told them.
 
 
tp.gif    Well, they towed it over with a strap pulled by an F250 diesel truck. The F250 looked like a toy truck compared to this behemoth.  With a push and a shove from the F250 the guys got it lined up and into one of my service bays. 
 
 
tp.gif    The big concern was the IDM relay, it kept chattering like a machine gun.  Instead of checking codes I thought it best just to start with a complete wire to wire check to determine if there was some lost signal that was causing the problem, or a wire that was scraped and grounding out.  Removing the inner fender on the driver side I could gain access to the Injector module (IDM) and the PCM (Power control module).  Seemed easier to start here than any place else.  It didn’t take long before I tracked down a problem.  On pin #71 of the (new) PCM there should have been 12 volts from the ignition.  No voltage at the terminal.
 
 
    Tracing the wiring diagram thru its maze it led back to the in-car fuse box on fuse #22.   I grabbed my test light and checked the fuse… (Rolling my eyes about now) the fuse,… oh man…  the fuse is blown.  Good grief… all this for a blown fuse.
 
 
tp.gif     Well, I better change the fuse, and see if it starts. Sure enough; it fired right up… sounded great, good throttle response, and no service lights. 
 
 
tp.gif    Now the big challenge, what blew the fuse in the first place?  Following the wiring diagram again…. I traced out all the components on the fuse circuit.  There was one that caught my eye as the likely culprit.  The brake cut-off switch mounted on the master cylinder.  (It’s the one that had the big recall a few years ago.)  
 
 
tp.gif    The updated replacement piece was in place but somebody forgot to secure the wires.  The replacement piece has a newer style connector and an adapter connector to allow you to attach it to the original style fastener. Which makes it a little longer than it originally was from the factory.  It was hard to tell where the new wire and connector started, and the old one ended, because the whole thing was lying on the exhaust manifold, and had melted down to a glob of wire and plastic.  
 
 
tp.gif    Looking around under the hood there were all kinds of new parts installed. The nicest part……they were all installed correctly. There were no other wires out of place, or any signs of scraps or melted wiring.  The important thing is that it runs, and the truck can go back to doing what it needs to do.  I think the biggest thing that threw everyone on this job was the chattering relay. It sounded bad, sounded expensive… but, all it turned out to be was a loss of proper voltage to the PCM, because a fuse blew from a lead that grounded out. This was due to the improper installation of one small component.  
 
 
tp.gif    The PCM couldn’t spread enough voltage and ground signals to all the necessary systems when it was missing the voltage it needed.  As the relay would engage, the voltage drop was too much to keep the relay engaged.  The IDM would pull more signal voltage as the relay would come to life.  Then the PCM would have to drop the ground signal to the IDM relay to compensate for the loss of voltage.  All this was going on very rapidly … on and off, on and off… making the machine gun sound coming from the IDM relay.
 
 
     The guys at the tire store were extremely grateful that I got the job done, so they could use the truck again.  For me, it’s another day at the shop.  I’ve got nothing but good things to say about the guys at the tire shop. Hey they tried, I’ll give them that. 
 
 
      But one thing I wish they would do next time --- CHECK THE BASICS—BEFORE BUYING PARTS!    It’s cheaper that way… 
 
 

View full article

  • Like 1
  • Thanks 1
Posted (edited)

Yes, always check simple things(basics) even on what might seem to something so complicated you wonder , will I  be  able to work on this! Gonzo, Another good story I guess from your vault of stories that you have compiled over the years.

Edited by kenk
  • Like 1
Posted
1 minute ago, kenk said:

Yes, always check simple things(basics) even on what might seem to something so complicated you wonder Chee, will I be able to work on this! Gonzo, Another good story I guess from your vault of stories that you have compiled over the years.

yep... busy week... spent a lot of "free" time working on getting the webinar just right and in the "can".   No time for new stories....again.....LOL

Posted
4 minutes ago, xrac said:

First The Basics - Diagnostics starts with powers and grounds NOT with parts and labor.  

That statement should be posted on a banner and hung up in every shop. A car diagnosed (actually not diagnosed but purported to have been) with a bad transmission by another shop was found to simple have a voltage problem caused by a bad battery and alternator. 

That sounds just like one of my old stories... "Shift Happens" were the entire tranny problem was a faulty ground lead because some dork installed a taller battery, and the cable wouldn't reach. So, he cut the chassis ground lead off of the neg. cable and tucked the end under the battery tray.  2 trannys later... I got to work on it.  Unbelievable.  LOL 

Posted

Diagnostics vs parts ... hmmmm sounds like a game played by a lot of mechanics and youtubers LOL... unfortunately parts seems to win out in most shops.. I don't know how many times people look way too deep for the problem.. I guess it is something that we learn as we get better that the basics need to be checked first.. sometimes the problem is right in front of your face but you can't imagine that being the problem so you look deep or in some cases throw more parts.. It must happen in all business or the saying "if it was a snake it would of bit ya" wouldn't of come about. All in all I think we all will be watching or playing in the game of Diagnostics vs Parts, who will win well who knows, but I think we all need to strive to play for the diagnostic team I hard those players seem to last longer and get paid a bit better , and have more loyal fans.

 

  • Like 1
Posted

While I'm teaching these days we've bugged the practice cars for the students. It's amazing how they ALL jump for a scanner instead of the diagrams to see if the problem is nothing more than a missing fuse.   Even though I stress the basics,  the mere thought of a problem being so simple is over shadowed by the complexity of the systems their examining.   

  • Like 1
Posted (edited)
Quote

How many fuel pumps were condemned due to empty fuel tanks? Back to basics.

  •  

 

I had an Expedition in the other week that had been at a shop, no start. They put a fuel pump in it and still couldn't get it to start.. So I took a look , bad central junction block.  Now if they had done some basic simple checks they would of seen they had no power going to the fuel pump. 
 
Edited by skm
  • Like 1
  • Haha 1
Posted

You made me smile reading your article. Here is my 0.02 cent story:

2005 Mercedes Benz E500 comes in from the local MB dealer, the complaint is that it has all kinds of intermittent electrical problems, it has new batteries, alternator, gateway and other modules, etc. On the preliminary inspection I find two ground straps broken, fix that and I hook up the picoscope to look at my current flow, see odd ripple, take a look at the serpentine tensioner and it's worn out with a new pulley installed. Changed it, car runs like a dream. Customer: "Are you sure that was it?! We spend over five grand in parts trying to fix it."

  • Like 1
  • Haha 1
  • Available Subscriptions

  • Have you checked out Joe's Latest Blog?

         0 comments
      It always amazes me when I hear about a technician who quits one repair shop to go work at another shop for less money. I know you have heard of this too, and you’ve probably asked yourself, “Can this be true? And Why?” The answer rests within the culture of the company. More specifically, the boss, manager, or a toxic work environment literally pushed the technician out the door.
      While money and benefits tend to attract people to a company, it won’t keep them there. When a technician begins to look over the fence for greener grass, that is usually a sign that something is wrong within the workplace. It also means that his or her heart is probably already gone. If the issue is not resolved, no amount of money will keep that technician for the long term. The heart is always the first to leave. The last thing that leaves is the technician’s toolbox.
      Shop owners: Focus more on employee retention than acquisition. This is not to say that you should not be constantly recruiting. You should. What it does means is that once you hire someone, your job isn’t over, that’s when it begins. Get to know your technicians. Build strong relationships. Have frequent one-on-ones. Engage in meaningful conversation. Find what truly motivates your technicians. You may be surprised that while money is a motivator, it’s usually not the prime motivator.
      One last thing; the cost of technician turnover can be financially devastating. It also affects shop morale. Do all you can to create a workplace where technicians feel they are respected, recognized, and know that their work contributes to the overall success of the company. This will lead to improved morale and team spirit. Remember, when you see a technician’s toolbox rolling out of the bay on its way to another shop, the heart was most likely gone long before that.
  • Similar Topics

    • By JustTheBest

      Premium Member Content 

      This content is hidden to guests, one of the benefits of a paid membership. Please login or register to view this content.

    • By Joe Marconi

      Premium Member Content 

      This content is hidden to guests, one of the benefits of a paid membership. Please login or register to view this content.

    • By carmcapriotto
      Thanks to our Partners, NAPA TRACS, and Today's Class Tim Iezzi and Ira Waldman introduce their upcoming training class, "Labscope Essentials for the Ball Joint Guy," designed to build strong foundational skills in labscope diagnostics. Aimed at bridging the gap between hands-on mechanical work and advanced technology, the class offers practical, hands-on learning with ongoing support. Tim and Ira break down the curriculum, target audience, and the importance of real-world application to reinforce concepts. They also highlight the critical role of continuous education and why shop owner involvement is key to technician growth and long-term success.
      Tim Iezzi, Iezzi’s Auto Service, Reading, PA
      Ira Waldman, Mallue's Automotive, Manasquan, NJ
      Watch Full Video Episode TST Big Event 2025: https://www.tstseminars.org/ "Labscope Essentials for the Ball Joint Guy" 9:00 AM - 5:00 PM on May 3-4, 2025. $495 per person (includes food and refreshments) Event Address: MACS Training Facility- 225 S Broad St, Lansdale, PA 19446 (back of the building). Contact us at: (484) 509-1494 or [email protected] Guest Introductions (00:00:00) Training Class Announcement (00:02:04) Class Focus Discussion (00:03:16) Investment in Training (00:05:07) Hands-On Learning Approach (00:05:47) Understanding Good vs. Bad Data (00:08:40) Foundation of Skills (00:10:48) Target Audience for the Class (00:12:01) Electricity Basics Requirement (00:12:14) Limitless Potential of Labscopes (00:13:10) Remote Refresher Training (00:14:00) Career Pathing and Continuous Education (00:15:16) Testing Techniques for Diagnostics (00:16:32) Supporting Students Post-Class (00:17:12) Creating a Comfortable Learning Environment (00:20:10) Assessments in Training (00:22:18) Hands-On Labs as Assessment (00:24:30) Accountability in Learning (00:26:22) Engaging Shop Owners in Training (00:27:46) Incentives for Technicians (00:27:58) Upcoming Training Classes (00:28:31)
      Thanks to our Partner, NAPA TRACS NAPA TRACS will move your shop into the SMS fast lane with onsite training and six days a week of support and local representation. Find NAPA TRACS on the Web at http://napatracs.com/ Thanks to our Partner, Today's Class Optimize training with Today's Class: In just 5 minutes daily, boost knowledge retention and improve team performance. Find Today's Class on the web at https://www.todaysclass.com/ Connect with the Podcast: -The Aftermarket Radio Network: https://aftermarketradionetwork.com -Follow on Facebook: https://www.facebook.com/RemarkableResultsRadioPodcast/ -Join Our Private Facebook Community: https://www.facebook.com/groups/1734687266778976 -Join Our Virtual Toastmasters Club: https://remarkableresults.biz/toastmasters -Subscribe on YouTube: https://www.youtube.com/carmcapriotto -Follow on LinkedIn: https://www.linkedin.com/in/carmcapriotto/ -Follow on Instagram: https://www.instagram.com/remarkableresultsradiopodcast/ -Follow on X: https://twitter.com/RResultsBiz -Visit the Website: https://remarkableresults.biz/ -Join our Insider List: https://remarkableresults.biz/insider -All books mentioned on our podcasts: https://remarkableresults.biz/books -Our Classroom page for personal or team learning: https://remarkableresults.biz/classroom -Buy Me a Coffee: https://www.buymeacoffee.com/carm -Special episode collections: https://remarkableresults.biz/collections The Aftermarket Radio Network: https://aftermarketradionetwork.com/ Remarkable Results Radio Podcast with Carm Capriotto: Advancing the Aftermarket by Facilitating Wisdom Through Story Telling and Open Discussion. https://remarkableresults.biz/ Diagnosing the Aftermarket A to Z with Matt Fanslow: From Diagnostics to Metallica and Mental Health, Matt Fanslow is Lifting the Hood on Life. https://mattfanslow.captivate.fm/ Business by the Numbers with Hunt Demarest: Understand the Numbers of Your Business with CPA Hunt Demarest. https://huntdemarest.captivate.fm/ The Auto Repair Marketing Podcast with Kim and Brian Walker: Marketing Experts Brian & Kim Walker Work with Shop Owners to Take it to the Next Level. https://autorepairmarketing.captivate.fm/ The Weekly Blitz with Chris Cotton: Weekly Inspiration with Business Coach Chris Cotton from AutoFix - Auto Shop Coaching. https://chriscotton.captivate.fm/ Speak Up! Effective Communication with Craig O'Neill: Develop Interpersonal and Professional Communication Skills when Speaking to Audiences of Any Size. https://craigoneill.captivate.fm/
      Click to go to the Podcast on Remarkable Results Radio
    • By Changing The Industry
      Bonus Episode - Mechanic Missteps and Diagnostic Dilemmas With Jake Barnes
    • By carmcapriotto
      Thanks to our Partner, NAPA Autotech
      Matt Fanslow dives into listener-submitted questions, covering:
      Multimeter recommendations (why he prefers insulation testers/meggers over basic DMMs). Electrical diagnostic strategies (schematics, scan tools, and stress-testing circuits). The "Flat Rate Test Drive" (a drivability diagnostic trick for load/PID analysis). Gaming picks (Elden Ring, Assassin’s Creed Shadows, and Days Gone Remaster). Scan tool advice for techs doing more drivability work.
      Timestamps:
      (00:00) – Intro 
      (02:33) – Multimeter recommendations: Why Matt avoids basic DMMs and prefers:
      Fluke 1587 or Pico TA467 (insulation testers for EVs/future-proofing). Used Vantage/Vantage Pro (graphing + scope functions). Curien (Bluetooth-enabled multimeter).
      (11:44) – Electrical diagnostic process:
      Start with a wiring schematic. Use a scan tool to check module inputs/commands. Stress-test circuits (e.g., load with a headlight for power/ground checks). Leverage relays for centralized testing (control/output sides).
      (22:48) – Shoutout to trainer Richard Velko.
      (23:17) – "Flat Rate Test Drive" explained:
      Monitor PIDs (load, MAF, MAP, O2 sensors) during WOT pulls to isolate drivability issues (fuel vs. restriction).
      (34:42) – Gaming corner: Elden Ring, Assassin’s Creed Shadows, and Days Gone Remaster.
      (38:53) – Scan tool recommendations for drivability:
      HP Tuners (budget-friendly, fast data logging). Used Snap-on Solus Edge/Ultra (enhanced OEM data). Shop responsibility (tools should be shop-provided!).
      Quotes
      "I don’t buy just a pure multimeter anymore... Get an insulation tester. You’ll need it for EVs/hybrids." – Matt "The ‘Flat Rate Test Drive’ stresses the engine while watching PIDs to split the problem in half." – Matt "For drivability, HP Tuners is my top pick—great data logging without breaking the bank." – Matt
      Tools & Resources Mentioned:
      Multimeters: Fluke 1587, Pico TA467, Vantage Pro, Curien. Diagnostic Tactics: Wiring diagrams, scan tool bi-directionals, current ramping. Games: Elden Ring, Assassin’s Creed Shadows, Days Gone Remaster. Scan Tools: HP Tuners, Snap-on Solus Edge, TopDon XTool.
      Final Thoughts:
      Matt’s takeaway? Invest in versatile tools (like megohmmeters) and lean on schematics/scan tools to avoid diagnostic rabbit holes.
      Thanks to our Partner, NAPA Autotech
      NAPA Autotech’s team of ASE Master Certified Instructors are conducting over 1,200 classes covering 28 automotive topics. To see a selection, go to napaautotech.com for more details.
      Contact Information
      Email Matt: [email protected] Diagnosing the Aftermarket A - Z YouTube Channel
      The Aftermarket Radio Network: https://aftermarketradionetwork.com/
      Remarkable Results Radio Podcast with Carm Capriotto: Advancing the Aftermarket by Facilitating Wisdom Through Story Telling and Open Discussion. https://remarkableresults.biz/
      Diagnosing the Aftermarket A to Z with Matt Fanslow: From Diagnostics to Metallica and Mental Health, Matt Fanslow is Lifting the Hood on Life. https://mattfanslow.captivate.fm/
      Business by the Numbers with Hunt Demarest: Understand the Numbers of Your Business with CPA Hunt Demarest. https://huntdemarest.captivate.fm/
      The Auto Repair Marketing Podcast with Kim and Brian Walker: Marketing Experts Brian & Kim Walker Work with Shop Owners to Take it to the Next Level. https://autorepairmarketing.captivate.fm/
      The Weekly Blitz with Chris Cotton: Weekly Inspiration with Business Coach Chris Cotton from AutoFix - Auto Shop Coaching. https://chriscotton.captivate.fm/
      Speak Up! Effective Communication with Craig O'Neill: Develop Interpersonal and Professional Communication Skills when Speaking to Audiences of Any Size. https://craigoneill.captivate.fm/
      The Aftermarket Radio Network
      Remarkable Results Radio Podcast with Carm Capriotto: Advancing the Aftermarket by Facilitating Wisdom Through Story Telling and Open Discussion
      Diagnosing the Aftermarket A to Z with Matt Fanslow: From Diagnostics to Metallica and Mental Health, Matt Fanslow is Lifting the Hood on Life.
      The Auto Repair Marketing Podcast with Kim and Brian Walker: Marketing Experts Brian & Kim Walker Work with Shop Owners to Take it to the Next Level.
      The Weekly Blitz with Chris Cotton: Weekly Inspiration with Business Coach Chris Cotton from AutoFix - Auto Shop Coaching.
      Business by the Numbers with Hunt Demarest: Understand the Numbers of Your Business with CPA Hunt Demarest.
      Speak Up! Effective Communication with Craig O'Neill: Develop Interpersonal and Professional Communication Skills when Speaking to Audiences of Any Size.
      Click to go to the Podcast on Remarkable Results Radio


  • Our Sponsors

×
×
  • Create New...