GODIAG GT101 4-in-1 Circuit Tester with Relay & Injector Diagnostics (DC 6–40V)

The GODIAG GT101 PIRT Power Probe is a versatile 4-in-1 multi-function circuit tester designed for 6V to 40V vehicle electrical systems. Built to reduce diagnostic and troubleshooting time, it simplifies testing of fuse boxes, relays, motors, lights, sensors, wiring, and communication circuits.

Featuring a large digital color display with clear visibility in both direct sunlight and low-light conditions, the GT101 is an essential electrical testing tool for professional technicians and DIY automotive enthusiasts alike.

GODIAG GT101 PIRT Power Circuit Probe User Manual

GODIAG GT101 Highlights

• 4-in-1 Multi-Function Power Probe — Combines circuit testing, fuel injector cleaning and testing, relay testing, and current detection in a single lightweight 2.5lb device — supports 6V to 40V systems for broad vehicle compatibility
• Circuit Testing with LED Indicators — Diagnoses open circuits, short circuits, polarity, and pulse currents — can supply power or test circuits for headlights, turn signals, windows, sunroofs, and more
• Fuel Injector & Relay Testing — Detects and cleans injectors to resolve starting, acceleration, and fuel consumption issues — tests relays when electrical components such as lights, horn, or starter fail
• 20ft Extension Cable & Built-in Flashlight — Long cable enables testing on large vehicles including trucks, buses, tractors, and mining vehicles — built-in flashlight ensures visibility in low-light conditions
• Overload Protection — Equipped with a 10A circuit breaker to prevent damage — automatically trips at 20A to protect circuits and extend device lifespan

GT101 Circuit Troubleshooting Short & Open Circuit

The GT101 quickly locates faults when vehicle headlights, turn signals, windows, sunroofs, or other components fail by detecting circuit voltage, polarity, and supplying power to confirm whether the issue is a circuit fault or a damaged component.

Steps:

1. Using the vehicle's circuit diagram, locate the suspected fault area and test with the GT101 to detect positive or negative voltage
2. Verify whether the circuit has correct polarity
3. Apply positive voltage directly to the malfunctioning component such as a headlight or motor:
   • If it works — The circuit has an open fault that must be repaired
   • If it does not work — The component itself is damaged and requires replacement

Relay Testing

If vehicle headlights, turn signals, horn, or starter motor fail despite the components testing correctly, a faulty relay may be the cause. Simply remove the relay from the vehicle, connect it to the GT101 via the adapter following the correct pin layout, and perform a quick and accurate relay test — compatible with both passenger vehicles and heavy-duty applications.

Fuel Injector Testing

If a vehicle exhibits hard starting, sluggish acceleration, or excessive fuel consumption, the fuel injector should be inspected. The GT101 tests the injector by activating it to open and close:

• If the ammeter displays normal readings and the injector responds — the injector is functioning correctly
• If readings are abnormal or there is no response — the injector is faulty and requires replacement

Fuel Injector Cleaning

When a fuel injector becomes clogged with carbon deposits or sticky residue, fuel delivery and atomization are reduced — resulting in poor engine performance. Cleaning the injector restores proper function.

Steps:

1. Prepare a pressurized fuel injector cleaner or carburetor cleaner with a nozzle diameter of 4mm
2. Secure the manual cleaning tool and hold the injector firmly to prevent it from being displaced by the cleaning pressure
3. Observe the following safety precautions throughout the process:
   • Avoid direct skin contact with cleaning fluid
   • Wear appropriate protective equipment
   • Never operate near open flames or heat sources
   • Perform cleaning in a well-ventilated area to safely disperse fumes and liquid

Wire Piercing Probe Usage (Compatible with GT101 / GT102 / GT103)

The GT101 can be used with a wire piercing probe to safely test live circuits without stripping wire insulation.

Steps:

1. Turn the red knob and pull the spring clip down to the correct position, clamping it securely onto the wire under test
2. Tighten the red knob to ensure solid contact between the probe and the wire
3. Insert the banana plug cable into the probe — if using the GT103, connect a multimeter to read voltage as the GT103 does not have a built-in display
4. Plug the other end of the banana plug cable into the GT101, GT102, or GT103

GODIAG GT101 PIRT Power Probe Features

• Supports power injection, measurement, ground testing, polarity checks, continuity testing, and direct component activation
• Easy-to-read volt-ammeter for instant voltage and current display
• Quick polarity switch provides positive or negative output for powering components such as fans and relays
• Simultaneous hot lead and ground lead operation for direct component activation
• Instantly identifies positive, negative, and open circuit conditions
• Detects poor ground contacts and locates shorts quickly without blowing fuses
• Tests switch and relay continuity in seconds
• Built-in circuit breaker for device protection
• Integrated flashlight for working in dark or low-light environments
• Audio tone indicator for easy menu navigation without looking at the display
• Long 20ft extension cable for convenient testing on large vehicles
• Compact, reliable, and user-friendly design
• Wide compatibility with 6V to 40V DC systems including cars, motorcycles, trucks, buses, tractors, mining vehicles, engineering equipment, and marine vessels

GODIAG GT101 Vehicle Coverage

The GT101 supports a wide range of 6V to 40V vehicles including cars and SUVs, motorcycles and ATVs, trucks and trailers, motorhomes and buses, boats and marine vessels, and tractors, mining vehicles, and engineering equipment — making it a versatile tool for automotive technicians, electricians, and DIY users across multiple vehicle types and industries.

GODIAG GT101 — 20ft Extension Cable

The GT101 comes with a 20ft (242-inch) extension cable, providing the reach and flexibility needed to perform diagnostics and electrical testing on large vehicles including trucks, buses, tractors, mining equipment, engineering vehicles, and marine vessels operating on DC circuits.

Comparison GODIAG GT101 vs GT102 vs TOPDIAG P200 vs AUTEL PS100

Function	GODIAG GT101	GODIAG GT102	TOPDIAG P200	AUTEL PS100
Product Picture
DC Voltage	✅	✅	✅	✅
AC Voltage	❌	❌	✅	✅
Positive & Negative Voltage Output	✅	✅	✅	✅
Component Activation	✅	✅	✅	✅
Current Measurement	✅	❌	✅	✅
Resistance Measurement	❌	❌	✅	✅
Open Circuit Detection	✅	✅	✅	✅
Short Circuit Detection	✅	✅	✅	✅
Fuel Injector Test	✅	✅	✅	❌
Fuel Injector Cleaning	✅	✅	❌	❌
Relay Test	✅	✅	✅	❌
Oscilloscope Function	❌	❌	✅	❌
Built-in Flashlight	✅	✅	✅	✅

GODIAG GT101 Specifications

Parameter	Details
Power Source	DC Car Battery (6V – 40V)
Power Consumption	0.5W
Operating Temperature	-5°C to 50°C
Storage Temperature	-5°C to 60°C
Box Dimensions	250mm × 187mm × 85mm
Main Unit Dimensions	180mm × 50mm × 27mm
Weight	1.2kg
Cable Length	620cm
Shell Material	ABS Eco-Friendly Material

 

GODIAG GT101 Package Contents

• 1 × GODIAG GT101 PIRT Power Circuit Probe Main Unit
• 1 × Battery Connection Clip
• 1 × Probe
• 1 × Probe Cap
• 1 × Fuel Injector Test Lead
• 1 × 10mm Fuel Injector Cleaning Connector
• 1 × 12mm Fuel Injector Cleaning Connector
• 1 × Simple Relay Test Adapter
• 5 × Simple Relay Connection Leads
• 1 × English User Manual