How do I hook up a diesel tachometer?
We recommend hooking up your diesel tachometer to either the alternator R or W terminal, crank sensor signal, or magnetic pulse sensor.
- To calibrate it, while hold the button down start the engine. The pointer to move to 1k rpm when in calibration
- Next, move the pointer to where your idle is by holding the button down. If you release and hold down again, it will move the other direction.
- Release the button, and after a few seconds the pointer will go to 0 and then current rpm.
- Your calibration is done! It is permanently stored in memory.
- This can be done multiple times if needed.
How do I calibrate my Tachometer?
To get into PPR (Pulses Per Revolution) calibration, you will press and hold the button down while power the gauge on (or menu button if you have 2 on the front)
You will determine your PPR based on the chart below. While in calibration, pressing and releasing the button will cycle through the options.
After 5 seconds, the gauge will exit calibration and save the PPR the pointer is currently on, return to 0 then show the RPM reading.
If you have a dual speedometer + tachometer, then you will set the calibration on the screen display instead, holding button down while powering on, press and release button to cycle through menu options, hold the button for 3-4 seconds to select "Set pulses per rev" menu option, then press and release to increase PPR. The PPR will save after 5 seconds of inactivity.
Tachometer calibration
| Engine Configuration | Distributor-Based
(Single-Coil) | Wasted-Spark
(Distributorless / Coil Packs) | Coil-On-Plug
(COP) | OEM ECU
Connection | Aftermarket ECU
Connection |
|---|
| 12 Cyl (4-Stroke) | 6 PPR | 1 PPR | 0.5 PPR | 2 PPR | 6 PPR |
| 10 Cyl (4-Stroke) | 5 PPR | 1 PPR | 0.5 PPR | 2 PPR | 5 PPR |
| 8 Cyl (4-Stroke) | 4 PPR | 1 PPR | 0.5 PPR | 2 PPR | 4 PPR |
| 6 Cyl (4-Stroke) | 3 PPR | 1 PPR | 0.5 PPR | 2 PPR | 3 PPR |
| 4 Cyl (4-Stroke) | 2 PPR | 1 PPR | 0.5 PPR | 2 PPR | 2 PPR |
| 2 Cyl (4-Stroke) | 1 PPR | 1 PPR | 0.5 PPR | 2 PPR | 1 PPR |
| 1 Cyl (4-Stroke) | 0.5 PPR | 1 PPR | 0.5 PPR | 2 PPR | 0.5 PPR |
| 3 Cyl (2-Stroke) | 3 PPR | 3 or 6 PPR | 1 PPR | 3 or 6 PPR | 3 or 6 PPR |
| 2 Cyl (2-Stroke) | 2 PPR | 2 PPR | 1 PPR | 2 PPR | 2 PPR |
| 1 Cyl (2-Stroke) | 1 PPR | 2 PPR | 1 PPR | 1 PPR | 1 PPR |
Calibrating single gauge tachometer:
What do I need to connect my Tachometer to?
You need to connect the tachometer to the vehicle's ignition system, or ECU tach output if applicable. Exactly where you connect to will depend on your vehicle's fuel delivery system. The PPR (Pulses Per Revolution) calibration will also vary based on where your signal is and how many cylinders your engine is.
If you have a single coil distributor, you will connect the signal to the negative coil terminal.
If you have a coil pack or coil on plug, you will connect to any trigger wire. (The wire that will be a different color from coil to coil)
If you have an OEM ECU, you will likely need a 4.7 KiloOhm pull up resistor tied to 12v to help strengthen the signal.
How do I connect a Tachometer to a GM LS1-LS7 engine’s ECU?
Please view the diagram below for more information on how to connect a Speedhut Tachometer to an LS ECU.
Setup the Tachometer to run 2 pulses per rev when connecting it to the engines' ECU.
Why is my tachometer bouncing all over the place?
If your tachometer is constantly jumping around, it is likely electrical interference. You can try shielding the signal wire with aluminum foil or foil tape and tie each end to ground, it is pretty common as the components the signal wire ties to tend to be electrically noisy.
