Sherwood Cooke Jr. isn’t standing in front of a full-wall diagram like those used to map the mob on detective shows. But he’s employing some truly special detective work in a recent TikTok clip from the royaltyautoservice (@Royaltyautoservice) account. The owner of Royalty Auto Service in St. Marys, Georgia opens the clip trying to narrow down what’s going on with a 2012 Ram 1500 truck. Its owner brought it in because its battery kept on dying.
Even after changing out the battery and alternator at a neighborhood shop, the truck’s battery continued to fail. Something’s afoot with the other components involved in the system that charges the battery off of the vehicle’s engine.
Rather than playing a frustrating game of whack-a-mole by installing a series of new parts (which would cost a lot of time and potential wastage) Cooke decided to use some diagnostic sleuthing via an assortment of readouts and wiring diagrams. His goal: To track down where the signaling around the battery and alternator was going awry.
Not the battery. Or alternator. What’s up with this Dodge Ram?
“It does not have a draw on the battery. Everything’s fine there. But the alternator is not charging. I don’t know how they tested the charging system, but possibly they went into the scanner and looked. And I think they might have got confused about what the scanner was saying,” he says at the outset.
It’s worth noting at this point that the electrical and charging systems of modern cars and trucks are pretty complex. And trying to confidently follow the mental decision diagram Cooke is racing through as he reads and assesses the data coming from perhaps a dozen diagnostic wires connected to the alternator… it’s pretty tough to follow even with several slow-motion replays.
For another look at how complicated everything involved with a vehicle’s alternator can be, here’s the fourth video that tries to explain how an alternator works. Cars, man. Amazing things. In short, alternators convert energy into electrical energy that powers-up your car and recharges its battery.
A solution
After about 10 minutes of sleuthing, Cooke determines that it’s the truck’s engine control module that’s the problem since it’s failing to initiate the proper charging of the battery that gradually runs down instead of being continuously charged. That’s about a $250 part.
“The alternator is able to do its job. It’s just that the engine control model is not able to make it do its job,” he said. “This is a way we can prove out the engine control module, not just throw one in there.”
Commenters on the clip are similarly impressed at how Cooke methodically and logically tracks down the source of the issue.
“Bro that’s amazing troubleshooting and experience is key,” one fan observed.
Another pointed the root cause of the issue elsewhere: “Aftermarket alternator that they put on can short out the (engine control module). Needs a mopar alternator or it will do it again.”
@royaltyautoservice Another example of how you test, not guess! #mechaniclife #mechanicsoftiktok #cartok #truck #ram #dodge #mopar #ram1500 #hemi #technician #automotive #viral #diy #fyp #foryou ♬ Pop beat BGM / long version(1283324) – nightbird_bgm
And another praised Cooke’s shop for having the diagnostic equipment readily available to do an expert job. “definitely good to diagnose when You have the tools an a shop willing to get the tools, i struggle diagnosing because of that,” they wrote.
Daily Dot reached out to Royalty Auto Service and Stellantis via email.
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