Shop Press

Shop Press is the news and idea hub for everything related to working on cars and trucks, focusing on repair, technology, and wrenching lifestyle.

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Hot Off the Press

Try Doing It the Wrong Way

Today’s article is composed of two quick tips that are distinct and different, but interrelated because they’re used on the same items: the humble fasteners we remove and install hundreds of times daily. These tips are both geared to newer techs since we all must find...

Modern Power Window Switches: Smarter than You’d Think

When was the last time you rolled down the power windows in an older car or truck? I’m talking at least pre-2000. The older, the better. As a passenger, you’ll find that every door has a mix of buttons, switches, locks, and handles to mess around with, plus maybe a...

It’s All About the Process

Man, it feels like just yesterday you graduated with that Associate’s in Automotive Tech, but nope, it's been three months already, and you've landed a solid job at ABC Auto Repair back in your hometown. The boss has been taking it easy on you, dishing out a bunch of...

Dealing with “System Lean” DTCs

The Engine Control Module (ECM) is always keeping an eye on the amount of fuel it is adding to the cylinders, and it'll throw a code when it figures it can't keep the mixture right where it needs to be. You might see codes like "system rich" or "system lean," and they...

Back Away from the Wrenches

Today’s article is more of a philosophical one than a pragmatic one. You see, we’re in the business of buying and reselling auto parts, servicing automobiles, and getting paid for our efforts. But as automotive professionals, we merely delay the inevitable. The...

The Misunderstood Ford 6.0

My wife and I are RVers and started our RV adventure with a 23’ toy hauler. When we started, we pulled the trailer with a Ram 1500 equipped with the 5.7-liter Hemi engine, and for most outings, it handled the task just fine. It wasn’t until we took a trip to the North...

Side Business

If your shop is a typical one, you wouldn’t turn down easy, profitable work, right? Of course not. Maybe it’s time your foreman, techs, and service writers sat down and talked through the car that isn’t a car: side-by-side (SxS). Like other not-immediately-obvious...

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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