2022 Top Godiag GT101 Circuit Tester with Probe Unbiased Review

Recommended by Scotty Kilmer Autofun and a few other mechanics, one of the customers from obdii365.com finally got the Godiag GT101 circuit tester and did a professional unbiased review here.


Part I: Device and Function Overview

Shipping was super fast and everything came packaged really well. I actually really like this Probe especially the price to features ratio is pretty good.


This is actually quite compact when I compare this to my voltmeter, it is actually a little bit smaller.

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It does have a 20-foot extension cord attached to it and that is because this probe is powered by the battery of our vehicle which is what enables this probe to do a lot of the testing that a normal voltmeter cannot do that easily.

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And this unit has an LED segment display which is quite interesting because normally we’ve seen LCD displays on here but LCD displays are prone to breaking especially when you are using this in a shop environment.

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Using the LED segment this is gonna be quite a bit resistant to abuse and towards the front of the unit.

So it’s like having a flashlight built-in onto this unit and we also have a little spot for the probe and the probe has a protective cover on here which is helpful so you don’t go around poking yourself just put that back on like so.

And the gt101 probe does not require any batteries in here, it is powered by the vehicles’ battery and that is done by connecting this plug right here to the set of alligator clips that they have included.

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This is an advanced power circuit probe tester. This is more than your typical tester. You can do so much with this. I’m talking you can test for voltage, test for continuity, bad ground, and even test relays and fuel injectors.

There is a very inserting feature godiag gt101 that I have not seen in other power probes. It has the ability to test and clean fuel injectors and what they have done is pretty clever.

They have manufactured these fuel injector adapters so their fuel injector cleaner can be connected here and then a fuel injector can be inserted here.

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Here they are made it easier for those with these adapters to activate the fuel injectors. They have included this little extension this gets connected here and then either one of these ends can go to the fuel injector which we can then activate and then we can trigger the cleaning process or the testing process.

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But using the same accessory plug that has included another feature that I have not seen either before which is the ability to test relays and the same deal will apply here this gets connected and locked in place and now I can take this and connect each one of these leaves to the end on the bottom of a replay and begin to test my relay in that way and be able to see if it clicks and works correctly or not.

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And finally, they include this instruction manual which covers the functionality of the probe and the different advanced tests that it can do on our vehicle or components.


Part II: On Car Test

Let’s test the probe on the vehicle.


Feature number 1

You can see it is already connected to the vehicle with the two alligator clamps.

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And the display is on. The very first feature is gonna be simply the flashlight and is you can see there are the dual lights that can eliminate when we’re working on the car.


Feature number 2

Is the voltmeter and that is this red LED display. This is great because instead of having two probes in a voltmeter setup here we only have one probe so that frees up our hand and we can quickly check voltages. I want to check the voltage of the battery I can go ahead and connect that and as you can see we have 12.5 volts.

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Now we also hear a beep and you saw a red light that indicates we have a positive voltage.


Feature number 3

That is going to be locating grounds. I am going to touch the negative now we have a been light instead of red light and the beep beep is different again.

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As you can see this allows us to locate ground anywhere on the vehicle by just touching the surface very quickly.


Feature number 4

Is the ability to injector power into components. Why is this handy perhaps we have tail light that is out on our vehicle all the way to the back of our vehicle and we don’t know if its the light bulb or if it’s the wiring. Image this was till mounted and I am able to access from behind and pearl the light with this I can confirm if the light turns on that means that the issue is with the wiring of a fuse or if the light does not turn on it is possible that the light bulb is out.

We can know how much a device pulls in terms of amps can allow us to know if there is an issue with it.

Not only can we power light bulbs we can power anything else such as a motor, the windows regulator on our car allowing us to confirm if it is the wiring or the component that has failed.

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Feature number 5

Is the ability to provide a ground connection. In feature number 4 you saw me turn on this bulb by providing a positive connection. But what if the light bulb was connected to the positive side. Let’s imagine that this was all the way to the back of the car and we suspected it was a ground problem

Here I can simulate the ground and confirm and yes by providing a ground the light bulb turns on, so that tells us that the wiring on the ground wiring to the light bulb all the way to the back of the car is what’s faulty.

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Feature number 6

The next function is a continuity meter. If there a break inside of this wire.

This wire is relatively short but if this wire travels all the way to the back of our car there could potentially be a break in here somewhere and we are struggling to see if the wire is good or not.

so we are going to connect the alligator clips from the power probe and I am gonna touch the other end.

If this lights up green and you get the nice little beep that means there is continuity the wire is not broken.

As simple as this feature is it can be very helpful in locating opens.

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Feature number 7

Is the ability to find shorts directly from the fuse or relay panel. You are going to be familiar with the schematic and wiring diagrams of a car before you can start to find shorts now the way that this will work is once you are familiar with the diagram and you have found the fuse for the cell where you suspect that there is a short the fuse can be pulled out. Now the fuse has two contacts I would inject power by pressing up into the first contact and there is a circle breaker in here, if the circuit breaker in here trips that means that side where I inject the power is the side that has a short and then I can now follow the wire and locate that correctly.

But if it doesn’t trip I still have one more side of the use which I can inject power from, and if that side of the fuse contact trips the circuit breaker internally we know that’s the side of the wire that I have to follow to locate the short. Once I have fixed the short I can reinstall the fuse and the circuit should work correctly at that point.

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Feature number 8

Probably one of the coolest features of the godiag gt101 circuit tester is the ability to test relays.

Relays, for the most part, you cannot really see visually if they are good or not so I have to remove it then I have to find a battery, find some cables to connect to the relay to test it out. The gt101 addresses that by creating this interface that allows us to test replays. Each of the wires in the gt101 power probe has been labeled with a number and a function. In the bottom of the relay they are the same numbers in there. So all I have to do is match each number to each wire and connect it to the relay.

I can grab the power probe and I can install the relay test and as you can see I can hear it clicking that’s first of all that’s a good indication because that tells me that the replay is functioning, also looking at the pc board in the bottom we have 3 lights that are on a blue, a green and a red. This is important because this can tell us something about what’s going on with the relay.

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Part III: Pros and Cons



  • The manual covers the test procedure, the presentation was really professional.
  • Great value ($79 only)
  • Nice quality, well made
  • This is more than your typical tester. You can do so much with this, i.e fuel injector and relay test
  • with extension cable and flashlight



  • Only thing I didn’t like was it has no case and the box it comes in was also the shipping box.
  • The only con, i wish it had a hard case, but it’s such a great tool otherwise, that I really don’t mind it one bit.


In sum:

Godiag GT101 power probe supports circuit testing, fuel injector tester, cleaning, relay tester, current amp meter & more.

This is not a cheap tool by no means. It’s really well made and can do a full diagnosis on the power system and charging system of your vehicle. This is definitely a go-to tool and one that deserves a spot in any mechanics toolbox. It is a must-have for any car technician whether you are doing this as a hobby or as a business, this type of probe is going to save you a lot of time over a simple voltmeter and it can do a lot more than that.