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FEATURE STORY

How Often Should You Really Flush Coolant? (VIDEO)

How Often Should You Really Flush Coolant? (VIDEO)

How do you know when it’s time to flush coolant? Technicians may have different views on the subject, but Dorman Training Center instructor Pete Meier explains how using a test strip at every service is a surefire way to get an accurate picture of the coolant’s health.

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Hot Off the Press

SLABs: Slow, Loud, and Bangin’

I love investigating specific subcultures, especially car subcultures. Doing so provides a unique lens through which to understand the complex dynamics of the broader society, including power, identity, defiance, and cultural change. Consider slab cars, for example....

Colin Chapman: The Philosopher of Motion (Part 2)

In Part 1 of this piece, we looked at Colin Chapman’s career up to the mid-60s. In this part, we’ll pick it up in 1965.Lotus wins the Indianapolis 500 In 1965, Chapman and Clark teamed up and made more racing history, this time across the pond at the Brickyard. Their...

How Often Should You Really Flush Coolant? (VIDEO)

Description How do you know when it’s time to flush coolant? Technicians may have different views on the subject, but Dorman Training Center instructor Pete Meier explains how using a test strip at every service is a surefire way to get an accurate picture of the...

Colin Chapman: The Philosopher of Motion (Part 1)

Car designers have a lot of brain synapses firing. Some designers are driven by the pursuit of beauty, while others are motivated by the pursuit of speed. Giorgetto Giugiaro, Marcello Gandini, and Battista Pininfarina, though responsible for cars that raced, were...

Maximum Voltage Reading – ASE Practice Question (VIDEO)

Description Technician A is using the min/max function of a digital voltmeter to test the battery and charging system on a customer’s vehicle. He notes a max reading of 17.2 volts has been recorded. Technician B says that the alternator has failed and is overcharging....

The Story of Dagmar Bumpers

If you’ve read my work here on Shop Press, you know I’m a sucker for chrome and mid-century automotive design. This week, I'd like to take a look at one of my favorite examples of that era: "Dagmar bumpers," the colorfully common slang used to describe the...

Should You Charge More When Dealing with Tire Sealant? (VIDEO)

Description Aerosolized tire sealant is widely available, and in some vehicles, it is used in place of a full-size spare. While this “tire repair in a can” might be the best solution in a jam, it creates a messy, stinky situation for a tech changing the tire for a...

Check Out This Hacky Diag Tool

by | Apr 3, 2025

Disclaimer: Dorman Products purchased this kit at full price.

In the interest of serious investigative reporting, I swiped the Shop Press credit card for $14.83 to try out a diag tool I thought looked super-cool: the relay bypass. What’s that? Short version: Imagine a relay-shaped manual SPST switch.

Longer version: A relay, at its core, is an electrically actuated switch. A relay bypass replaces that function with a manual switch. Some bright soul got the idea to take six common relays and fit them with on-off rocker switches, the end result possessing the common “footprints” for automotive (“ice cube style”) relays. They can then be swapped into a vehicle fuse box or power center to give a technician manual control of the item receiving power.

Brilliant.

Now I thought Andy’s find of resettable breakers in a fuse footprint was interesting, but I was a little dubious about how often I might reach for them as a tech. But these babies? I feel a little differently.

What do I love here? A few things. I can test a component and its controlling relay for function at the same time. I don’t have to look up pinouts for common relays that I forget every time. I don’t have to open up a relay and put power to it to see if it’s working. I don’t have to build/scrounge/dig for stuff to make jumper wires. These sort of turn diagging relays from a painful punishment into something super-fast.

There’s really only one downside I can see: some of these are fitted with 10A switches, and they’re not fused. So, y’know, ya gotta use ‘em with caution or you’ll blow up one of your new toys. But that doesn’t seem like a very expensive proposition to me.

You know when I’m gonna use these? The next time someone brings me in a full fuel tank on a job where it needs to come down. Fuel caddy. Hmmph!

Now I thought Andy’s find of resettable breakers in a fuse footprint was interesting, but I was a little dubious about how often I might reach for them as a tech. But these babies? I feel a little differently.

What do I love here? A few things. I can test a component and its controlling relay for function at the same time. I don’t have to look up pinouts for common relays that I forget every time. I don’t have to open up a relay and put power to it to see if it’s working. I don’t have to build/scrounge/dig for stuff to make jumper wires. These sort of turn diagging relays from a painful punishment into something super-fast.

There’s really only one downside I can see: some of these are fitted with 10A switches, and they’re not fused. So, y’know, ya gotta use ‘em with caution or you’ll blow up one of your new toys. But that doesn’t seem like a very expensive proposition to me.

You know when I’m gonna use these? The next time someone brings me in a full fuel tank on a job where it needs to come down. Fuel caddy. Hmmph!

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