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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...

Power and Ground Testing on an Electrical Circuit

I'll never forget this one day in the shop. One of the other techs was wrestling with an electrical gremlin and swung by my bay for some backup. "Pete, mind giving me a hand? I've got this GMC pickup with a blower motor that's running super slow. I checked the power...

ADAS Repairs: Why Calibration Is A Must

Modern vehicles equipped with Advanced Driver Assistance Systems (ADAS) are truly marvels of engineering. What started as high-end options found only on luxury cars can now appear as standard equipment on some econo-boxes (e.g., blind spot detection). That means it is...

Sergio Pininfarina: Sculpting Speed and Beauty in Metal (Part 2)

In Part 1 of this piece, we looked at Sergio Pininfarina’s career up to 1987. In this part, we’ll take a look at his innovative concept cars. Concept cars: when art defied convention Sergio encouraged his designers to explore new ideas through concept vehicles that...

The Only Thing Better Than Making Money Is Not Losing It

Service writers, this piece is aimed squarely at you. You may be aware of many of the costs of doing business. Recognizing potential costs and preventing them from eating into your shop’s productivity is one of the skills that separates a good writer from an...

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...

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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