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.

From the creative minds at:

FEATURE STORY

Hot Off the Press

Is It Ever Safe to Reuse Torque-to-Yield (TTY) Fasteners (VIDEO)

Description Torque-to-yield fasteners are designed to deform during installation to ensure a secure connection. If a TTY fastener looks to be in good shape after removal, can it be reused? Pete Meier explains why these single-use bolts should always be replaced for...

Do You Survey Your Customers, and How?

Recently, I had the opportunity to take my car to a body shop (it’s a long story). Once the work was done and I was checking out, the office manager mentioned to me that they would be sending me a customer satisfaction survey and encouraged me to fill it out. Then she...

Interpreting Compression Tests–ASE Practice Questions (VIDEO)

Description Technician A has just completed a running compression test using a mechanical compression gauge. Technician B says that the test is used to check the volumetric efficiency of the engine. Technician A says that the higher-than-expected readings indicate a...

Do I Need a Tune-up?

If you’re like me, you might cringe a little. More often than not, they’re hoping this magical procedure will fix some mysterious issue with their car. But let’s break it down: what is a tune-up, anyway? Most dictionaries describe a tune-up as “a general adjustment to...

PSA: Be Safe With Brake Cleaner

If you work in a shop (and if you’re reading this, chances are you do), you are undoubtedly familiar with brake cleaner. And, if you know the scent of brake cleaner, you probably know that using it is not great for your health if it comes in contact with your skin,...

Compression Testing | ASE Practice Questions (VIDEO)

Description Technician A has just completed a dry compression test of a four-cylinder engine. All four cylinders are below specification by about the same amount. After performing a wet compression test, values remained unchanged. What could cause this condition? A)...

When a Voltmeter Isn’t Enough (Video)

Description With the variety of electronically controlled systems on a modern automobile, the days when a test light or simple voltmeter was enough to diagnose problems are long gone. Using a digital storage oscilloscope (DSO) can make troubleshooting faster and more...

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!

The articles and other content contained on this site may contain links to third party websites. By clicking them, you consent to Dorman’s Website Use Agreement.

Related Articles

Shop Press Comment Policy

Participation in this forum is subject to Dorman’s Website Terms & Conditions. Please read our Comment Policy before commenting.

Subscribe
Notify of
guest
2 Comments
Newest
Oldest Most Voted
Inline feedback
View all comments