The Danger of "Good Enough"—How EMI Shut It All Down...


June 24th, 2025 — Issue #0001

The Danger of "Good Enough"—How EMI Shut It All Down...

...And The $0 Fix That Outsmarted a Cadillac XT5 for 2 Months

Hi Reader,

Welcome to your weekly boost of inspiration from the shop floor. Torque Authority is not your average industry blog—it's a spark fired from the shop meant to reignite your drive, your grit, and your purpose.

Each edition delivers a hint of humor and a dose of inspiration drawn from real moments under the hood—lessons on leadership, resilience, and persistence.

The aim of this newsletter is to help you build a highly skilled, confident, and high-paying automotive future—on your terms.

Join Torque Authority Hub: Where Automotive Technicians Transform into Diagnostic Daredevils. Embrace your worth, master your craft, and drive towards financial autonomy with a community that gets it.

From the Driver's Seat—Featured Story

You plug in the scan tool. Nothing. No codes.

You scroll through the data parameters. Nothing stands out.

No Freeze Frame. No breadcrumbs. No symptoms but a very intermittent, and equally very vague transmission shift service warning message on the dash which you haven't even witnessed yourself.

That's when it starts—the tightening in your chest, the sweat on your forehead, the rising anxiety.

The vehicle has already been down for months, and the customer's patience is worn thinner than brake pads grinding into the rotor, long past their warning squeal.

How would you handle this?

Well, this is how it went down.

First, the parts cannon. An electronic parking brake switch here. A column shifter assembly there. Next up both parking brake actuators as well as a transmission valve body.

Educated guesses can only go so far sometimes.

But after weeks of digging and monitoring various data values, the stars began to align.

While driving the vehicle and monitoring the Transmission Park Valve Position Sensor Data Parameters, I noticed an odd anomaly after the engine restarted during an auto-stop-start event.

There are two redundant Transmission Park Valve position sensors inside this transmission. These two are supposed to match each other and read the same value of 'Park' when the gear selector is in 'Park', and 'Out of Park' while driving.

Except they didn't after an Auto-Stop-Start restart event. And only after the engine restarted did I notice one of the sensors read 'Park' while the other sensor read 'Out of Park'.

After cycling the key to OFF then back ON, these two sensors matched each other again.

Huh???

Must have been a glitch, I thought. Except it kept happening.

I drove the vehicle through at least 25 different auto-stop-start events to try to figure out what was happening. But it made no sense—why would these sensors not match ONLY after the engine auto-restarted?

I connected an oscilloscope to these sensor circuits directly to make sure the computer module—or my brain—wasn't just going crazy.

Sure enough, the sensor voltage was changing. So, something was indeed knocking this sensor reading out of whack whenever the engine auto restarts.

But what was it? The circuits were intact, neither was shorted to power, ground, nor any neighboring circuits.

I reached out into the infinite void of a large group chat of colleagues, hoping to find an answer. It wasn't until reaching out to my network the third time that someone gave me an unexpected but surprisingly helpful tip.

Someone casually suggested, ‘Have you checked the battery cables?’

The battery cables?

I blinked. Stared. Laughed out loud.

What could those cables possibly have to do with these internal transmission sensor readings? Sure buddy, I'll check those cables. I'll also make sure to check my shoelaces the next time the Wi-Fi acts up.

Out of options, I opened the hood and stared at the battery cables, still laughing to myself.

But then, I noticed something. Something didn't quite look right.

Intrigued, I walked over to another XT5 of the same model year just a few bays over from where I was working.

The positive cables on this like unit were routed above and secured to the top of the engine bracket, unlike the customer's vehicle.

Someone else has been in here, I thought to myself. And they didn't pay attention to where the positive cables are designed to go.

I followed the cables. Down under hoses and the under the top bracket (where it was supposed to be secured), laying instead against the edge of the transmission, and from there on out to the starter motor and alternator.

Then it hit me.

The cables were literally LAYING against the edge of the transmission case. But not just in any 'ol spot. They were positioned above the exact location where the Transmission Park Valve Position Sensors were located just inside the transmission case.

Now things started to make sense. I thought to myself, what if the position of the battery cables is resulting in an EMI effect when the engine auto restarts?

I routed these positive cables back to the proper position and drove the vehicle again through 10 more auto-stop-start cycles. No more warning messages, and the Transmission Park Valve Position Sensor values stayed the same during each restart event.

I was shocked. My hypothesis was right—the engine auto-restart caused a rush of current flow through the positive battery cable to the starter motor—and right next to the park valve position sensors.

Apparently, this rush of current was just enough EMI to knock the Sensor 1 position from a value of 'Out of Park' back into 'Park'.

I learned a few key valuable lessons from this case:

  1. The little things matter. Even something as simple as where a cable is designed to be routed is important.
  2. Paying attention to these little details can prevent strange anomalies like THIS one.
  3. Having a community of like-minded individuals is extremely valuable, particularly when you get stuck.

To the guy who installed these positive cables in the wrong place: just doing a job 'good enough' is a dangerous philosophy to live by.

And to you the reader: I'm sure you know the value of having access to a community of other wise-cracks and sarcastic sages who can get you pointed in the right direction.

That's why we've created a free online Skool community where fellow troubleshooters, thinkers, and diagnostic detectives can swap stories, wisdom, and wiring diagrams. 'Torque Authority' isn't just a newsletter, it's the start of a movement. Come be a founding member by joining the party here:

Join Torque Authority Hub: Where Automotive Technicians Transform into Diagnostic Daredevils. Embrace your worth, master your craft, and drive towards financial autonomy with a community that gets it.

I hope you enjoyed the story! Please share this article with a friend if you did.

This week's Featured Story is brought to you by:

T. W. Mulder

Author | Writer | ASE Certified Master Technician | Field Service Engineer

Torque Spotlight

In this section each week we highlight a person—an innovator, subscriber, engineer, or even a business—who has made a positive impact in our industry. This is the place in Torque Authority where their authority in the Automotive Industry is highlighted.

This week's highlight is on Roy Foster's Automotive in Reno, Nevada.

Roy Foster's Automotive is a family-owned repair facility providing auto repair and maintenance services. Roy Foster's Automotive 2023 AAA Best in Repair Gold winner and NAPA Shop of the year. Roy Foster's specializes in full-service auto repair. Since 1947, Roy Foster's Automotive has provided the residents of Reno with extraordinary auto repair services.

Pit Stop Wisdom

One quote of wisdom for you to consider this week...

"Who you spend time with is who you become. Proximity is power."

- Tony Robbins

Toolbox Tip

This is where we share one practical resource: a tool, app, book, strategy, or event which can have a positive impact in YOUR life.

This week's Toolbox Tip is on one of my favorite books titled Atomic Habits by James Clear.

James Clear’s Atomic Habits is a masterclass in how small, consistent actions can lead to massive long-term results—a principle that resonates deeply in the world of automotive repair. For technicians, where precision, consistency, and attention to detail are everything, the book’s core idea of improving just 1% each day can translate into fewer diagnostic errors, faster workflows, and stronger professional habits. Whether it’s organizing tools more efficiently, documenting repairs more thoroughly, or simply building the discipline to double-check every connection (yes, even that battery cable), this system-focused approach empowers techs to level up not just their skills, but their mindset.

Your Turn Behind the Wheel

🔧 Question of the Week What’s the weirdest piece of advice you’ve ever gotten during a repair—and (bonus points) did it actually work? Let us know by responding to this email!

📊 Quick Poll When you're stumped, what's your go-to first move?

  • Fire up the forums
  • Phone a friend
  • Pray to the diagnostic gods
  • Jiggle some wires and hope for the best

✍️ Share Your Story Ever fixed something totally by accident? We want to hear about your unintentional victories and happy mistakes—reply with your story and we just might feature it in a future edition.

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To your confident, high-paying automotive future.

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