Description
The Speedhut 4-1/2″ 6K RPM Shift-light Diesel Tachometer (R45-TC8-REV) is a precise and functional instrument designed to provide accurate RPM readings for diesel engines. This gauge features an integrated shift light system to help drivers optimize performance and gear changes. With its clear display and included wiring harnesses, it offers a straightforward solution for monitoring your engine’s speed.
KEY FEATURES AND BENEFITS:
- Provides accurate RPM readings up to 6,000 for diesel engines.
- Features a built-in, programmable shift light to indicate optimal shift points.
- Offers a clear and easy-to-read 4 1/2 inch display.
- Includes necessary wiring harnesses for power, lighting, and RPM signal connection.
- Designed for compatibility with various diesel signal types (alternator with ‘R’ or ‘W’ terminal, crank sensor, magnetic pulse sensor).
- The internal shift light aids in achieving better fuel efficiency and performance.
- LED illumination ensures excellent visibility during both day and night driving conditions.
SPECIFICATIONS:
- Gauge Type: Tachometer
- Tachometer Signal Type: Diesel (alternator with an ‘R’ or ‘W’ terminal, crank sensor signal, magnetic pulse sensor)
- Range: 0 – 6,000 RPM
- Size: 4 1/2 inch (114mm)
- Hole Size: 4.23 inches (108mm)
- Internal Shift Light: Yes
- Ships With:
- 3 ft Power & Lighting Harness – for LED Lit Gauges and Clocks
- 8 ft Htz Tachometer Harness (LED Lit)
HOW TO USE:
- Preparation: Disconnect the negative terminal of your vehicle’s battery for safety.
- Mounting: Locate a suitable 4.23-inch diameter opening in your dashboard or instrument panel. Insert the tachometer and secure it using the provided mounting hardware (typically a spin-lock ring).
- Wiring – Power and Lighting: Connect the 3 ft Power & Lighting Harness. Typically, this will involve connecting a wire to a 12V power source (ignition switched is recommended), a ground wire, and potentially a wire to your vehicle’s lighting circuit for dimming or separate day/night illumination. Refer to the specific wiring diagram included with the product.
- Wiring – Tachometer Signal: Connect the 8 ft Htz Tachometer Harness to the appropriate signal source on your diesel engine. This could be the ‘R’ or ‘W’ terminal on the alternator, the crank sensor signal wire, or the output from a magnetic pulse sensor, depending on your engine type. Consult your vehicle’s service manual to identify the correct signal wire.
- Calibration (PPR Setting): This step is crucial for accurate RPM readings. Typically, you will need to access a menu on the tachometer (often by pressing and holding a button during power-up) to set the Pulses Per Revolution (PPR) value that corresponds to your engine. Refer to the Speedhut product manual for the specific procedure and the correct PPR for your engine.
- Shift Light Programming: Once the tachometer is functioning, you can program the shift light to activate at your desired RPM. This usually involves navigating a menu on the gauge to set the RPM trigger point for the shift light. Some models may also allow setting a range for warning lights before the main shift light. Consult the product manual for detailed instructions.
- Testing: Reconnect the negative battery terminal and start your vehicle. Verify that the tachometer is displaying the correct RPM readings and that the shift light functions as programmed.
BENEFITS OF USING THE SPEEDHUT 4-1/2″ 6K RPM SHIFT-LIGHT DIESEL TACHOMETER (R45-TC8-REV):
- Accurate Engine Monitoring: Provides precise real-time information about your diesel engine’s RPM, crucial for optimal operation and maintenance.
- Improved Performance: The integrated shift light allows for consistent and precise gear changes, potentially leading to better acceleration and fuel efficiency.
- Enhanced Driver Awareness: Quickly and easily monitor engine speed, preventing over-revving and potential engine damage.
- Clear Visibility: The 4 1/2 inch display with LED illumination ensures readability in various lighting conditions.
- Straightforward Installation: Comes with the necessary wiring harnesses, simplifying the installation process.
- Versatile Compatibility: Designed to work with different types of diesel engine RPM signal outputs.
FEATURES:
- Clear analog display with a 6,000 RPM maximum reading.
- Integrated shift light with programmable activation point.
- Designed specifically for diesel engine RPM signals.
- 4.23-inch mounting diameter for common gauge installations.
- Includes a 3 ft power and lighting connection cable.
- Comes with an 8 ft harness for the tachometer signal input.
- LED backlighting for enhanced visibility.
- Suitable for standard unit systems.






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