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

Sergio Pininfarina: Sculpting Speed and Beauty in Metal (Part 1)

There is little argument that Sergio Pininfarina was a major influence in 20th-century car design. The proof is in the cars … many of them legendary Ferraris. Building on his family’s legacy, he led Carrozzeria Pininfarina into a period where design and engineering...

Best of Shop Press 2025

Another year is in the books here at Shop Press, and we thought we’d take this time to look back at 2025's most notable articles, videos, and more. Here’s what you (and we) loved this year on Shop Press as we head into 2026.Most-viewed overall Our most-viewed post...

Lash is Cash

There are some items on a maintenance checklist that neither mechanics nor writers will recommend. Sometimes that’s because a visual inspection or assessment seems at odds with an overly rigorous service schedule. Sometimes, the condition of the car or the financial...

Clean It or Crack It

Picture this: You’re installing a cylinder head, you’re tightening a head bolt to spec, and you’re feeling good—until crack! The sound every wrench-turner dreads hearing: your engine block saying goodbye to its structural integrity. So, what happened? Chances are, a...

Set the Toe and Go!

“Oh, and it’s pulling to the right a bit. Can you check that out?” If you run a small shop with just one or two service bays, it’s likely you’ve heard this before, since in a small shop the service writer, mechanic, foreman, parts department, and lube tech are often...

Chrome Overload: GM’s “Mistake of ’58”

I love chrome and mid-century automotive design. But I recently found a video that made me question my belief that there’s no such thing as too much chrome. The video is called “Mistake of '58: The GM Chromemobiles and Far Out '59s” from YouTuber Ed’s Auto Reviews....

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