JEGS 41307 3-3/4 inch Pedestal Mount Tachometer User Manual

1. Introduction

This manual provides detailed instructions for the installation, operation, and maintenance of your JEGS 41307 3-3/4 inch Pedestal Mount Tachometer. Designed for automotive applications, this tachometer accurately displays engine RPM, featuring a clear white face and illuminated pointer for optimal visibility. Please read this manual thoroughly before installation and use to ensure proper function and safety.

2. Product Features

• RPM Range: 0-8,000 RPM for precise engine speed monitoring.
• Display: 3-3/4 inch diameter with a white face and chrome bezel for clear readability.
• Housing: Durable chrome housing.
• Sweep: 270-degree needle sweep for enhanced accuracy.
• Mounting Versatility: Can be mounted on a flat surface or a steering column (steering column clamp sold separately).
• Signal Compatibility: Compatible with 2, 3, and 4 PPR (Pulses Per Revolution) signal inputs from standard ignition coils (suitable for older 4, 6, and 8 cylinder vehicles).
• ECU Compatibility: Works with 5 Volt and 12 Volt signal inputs from ECUs (Electronic Control Units), ignition controls, and tachometer adapters.
• Illumination: White LED through-dial lighting and an illuminated pointer ensure easy viewing in low-light conditions.

3. Package Contents

Verify that all the following components are included in your package:

• (1) JEGS 41307 Pedestal Mount Tachometer
• (1) Pedestal mount base
• (1) Mounting base to tachometer body machine screw: 4mm-0.7 x 1.1875 in. long, Phillips pan head
• (1) Mounting base to tachometer body Nut: 4mm-0.7
• (3) Mounting base metal screws: #8 x 1/2 in. long, tapered Phillips head
• (1) Plastic wire tubing: .250 in. I.D. x 4.250 in. long
• (1) Installation Instructions (this document)

4. Installation Guide

Proper installation is critical for the accurate and safe operation of your tachometer. If you are unsure about any steps, consult a qualified automotive technician.

4.1 Mounting the Tachometer

1. Select Mounting Location: Choose a flat, stable surface on your dashboard or a suitable steering column location (requires a separate steering column clamp). Ensure the location does not obstruct your view of the road or other critical instruments.
2. Attach Pedestal Base: Secure the pedestal mount base to your chosen surface using the three #8 x 1/2 inch metal screws provided.
3. Attach Tachometer to Base: Connect the tachometer body to the pedestal mount base using the 4mm-0.7 machine screw and nut. Adjust the angle for optimal viewing before tightening securely.

Figure 1: Front view of the JEGS 41307 Tachometer mounted on its pedestal base.

4.2 Wiring Connections

Before making any electrical connections, disconnect the vehicle's battery to prevent electrical shorts or damage. Refer to your vehicle's service manual for specific wiring diagrams if necessary.

Figure 2: Rear view of the tachometer showing the wiring harness and adjustment screw.

The tachometer typically has four wires for connection:

• Red Wire: Connect to a switched 12V ignition source. This wire provides power to the tachometer when the ignition is on.
• Black Wire: Connect to a good chassis ground point. Ensure a clean, secure connection.
• Green Wire: This is the signal wire. Connect it to the negative (-) side of the ignition coil or the tachometer output signal from your ECU/ignition control module.
  • For standard ignition coils, connect to the terminal that goes to the distributor or ignition module.
  • For ECU/ignition control signals, ensure the signal is 5V or 12V compatible.
• White Wire: Connect to a 12V switched power source for the LED illumination. This can be connected to the vehicle's headlight switch or a dedicated dash light circuit.

Use the provided plastic wire tubing to protect the wiring harness from abrasion and heat. Secure all connections with appropriate connectors and insulation.

4.3 Setting PPR (Pulses Per Revolution)

The JEGS 41307 tachometer is compatible with 2, 3, and 4 PPR signal inputs. The PPR setting is typically adjusted via a small switch or dial on the back of the tachometer (refer to Figure 2 for location). Consult your vehicle's specifications or engine type to determine the correct PPR setting for your application:

• 4-Cylinder Engines: Often use 2 PPR.
• 6-Cylinder Engines: Often use 3 PPR.
• 8-Cylinder Engines: Often use 4 PPR.

Incorrect PPR settings will result in inaccurate RPM readings. Adjust this setting before final installation and testing.

5. Operation

Once properly installed and wired, the JEGS 41307 Tachometer will automatically display your engine's RPM when the ignition is on. The white LED backlighting and illuminated pointer will activate when the white wire receives 12V power, providing clear visibility during nighttime driving.

Observe the needle movement to monitor engine speed. Avoid operating your engine beyond its recommended RPM limits as specified by the vehicle manufacturer.

6. Maintenance

The JEGS 41307 Tachometer requires minimal maintenance. Keep the face and chrome bezel clean using a soft, damp cloth. Avoid abrasive cleaners or solvents, as these can damage the finish or the clear lens. Periodically check wiring connections for tightness and ensure they are free from corrosion.

7. Troubleshooting

If your tachometer is not functioning correctly, consider the following troubleshooting steps:

• No Power/No Illumination:
  • Check the red (power) and black (ground) wire connections for continuity and secure contact.
  • Ensure the white (illumination) wire is receiving 12V when lights are on.
  • Verify that the vehicle's battery is charged and connections are secure.
• Inaccurate RPM Reading:
  • Verify the green (signal) wire is correctly connected to the ignition coil negative terminal or ECU tach output.
  • Check the PPR (Pulses Per Revolution) setting on the back of the tachometer. Ensure it matches your engine's cylinder count (e.g., 4-cylinder = 2 PPR, 6-cylinder = 3 PPR, 8-cylinder = 4 PPR).
  • Inspect the signal wire for damage or shorts.
• Erratic Needle Movement:
  • Ensure all wiring connections are tight and free from corrosion.
  • Check for electrical interference from other vehicle components.
  • Verify the signal source is stable.

If problems persist after performing these checks, contact JEGS customer support for further assistance.

8. Specifications

9. Warranty and Support

For information regarding warranty coverage, technical support, or replacement parts, please contact JEGS customer service directly. Keep your purchase receipt and product model number (41307) handy when contacting support.

You can typically find contact information on the official JEGS website or through your original point of purchase.