Introduction

The Main9 Simpleharness is a cable that hooks up to the 9 pin Mains plug of Phaserunner and Baserunner motor controllers to bring out industry standard HiGo plugs for a display, throttle, and ebrake cutoffs near the handlebar. Unlike the Superharness, this more basic cable does not have active circuitry to process and modulate various signals. It is an ideal lower cost harness option for systems using a bidirectional throttle or for geared motor systems that don't have regen.

Compare to Cycle Analyst systems

Features

• Supports Bidirectional Throttle for Proportional Regen Control 
• DC Power Port for Front Light, Up to 1.0 amps at battery voltage, but power always present when system is on
• Ebrake Cutoff Plug Automatically clamps throttle signal to 0.5V, providing a fixed regen brake force
• Compact Design Overmolded circuitry is not much larger than a typical cable junction

Differences with Superharness

We introduced the Superharness in 2023 when there were limited options for bidirectional throttles and additional circuitry was needed to bring regenerative braking control into an ASI motor controller without a Cycle Analyst.  Now that bidirectional throttles are readily available, the missing piece that made the superharness essential for modulating regen braking was no longer needed for a fully functional system. So we introduced the Simpleharness as a lower cost option. The following table summarizes the key functional differences between the simpleharness and the superharness.

Feature	Simpleharness	Superharness
Bidirectional Throttle Support	YES	YES
Normal Throttle Support	YES	YES
Regen Braking Modulated via Normal Throttle	NO	YES
Support for 2nd Throttle or Analog Ebrake for Regen Control	NO	YES
Ebrake Cutoff Input	YES (fixed regen ~0.5V)	YES (regen variable via throttle 0.0-0.6V)
Front Light Port	YES (but always powered on)	YES (and Controllable via Display)
Rear Light Port	NO (But can attach Y splitter to front light)	YES (with various blinking and brake light modes)

In short, if you are using a bidirectional throttle and are fine with a front light power port that is always on (when a battery is connected and turned on), then the Simpleharness will serve you just fine.  But if you want to modulate regen with a separate throttle or analog brake lever, OR you want to have front and rear lights that are controlled by the display, then you will still need a Superharness. 

Connections

Here is the plug standard for the device

	Main9 This hookup matches the 9 pin plug present on the V4 and later Phaserunner and Baserunner motor controllers. However, the firmware to properly support 3rd party displays is only present on the V6 motor controllers.
	Display The display plug is a 5 pin female Higo, using one of the 3 common pinout standards. Connection to a display with the same pin style but a different pinout will almost always damage the display, harness, and motor controller as the full battery voltage pins are swapped around.
	Throttle The throttle plug is a 3 pin female Higo in the most popular industry format. This supports regular throttles with a 1-4V signal range, as well as bidirectional throttles with a 1V center point that go down to 0V for regen control.
	Ebrake The ebrake connector is a 4 pin female Higo and includes both a digital input and an analog input pin to support both ebrake styles. The digital brake input when shorted to ground has the effect of clamping the actual throttle signal to 0.5V.   The analog ebrake pin is not normally used as it is connected to the same input of the  torque sensor line on the motor controller.
	Front DC Power The front DC power port is a 5.5x2.1mm jack designed primarily for front lights. It has power whenever the system is on, and can't be turned on and off via the display. As a result we recommend pairing this with a front light that has its own separate on/off switch.

 

Compatibility

Full functionality of the Simpleharness and display requires a V6 Phaserunner or Baserunner motor controller with at least the 6.025 firmware installed.  Controllers sold before 2023 typically had 6.023 firmware, which has a bug preventing the assist levels from properly toggling up and down.  The V4 and V5 baserunner controllers also have a 9 pin mains plug, but these run an older 5.9XX ASI firmware that can't be updated to 6.XX because they use a more limited microchip.

Troubleshooting

 

Occasional ERR30 Message: At very high motor currents especially during regen braking, the ASI motor controllers can be vulnerable to signal noise on the Port2 communication bus used by the display and you may briefly see "Error 30" on the screen. During this time, the throttle and PAS assist continue to function without any hiccup so there is no loss in power as a rider, but you will not see speed and watts on the display itself. The problem will clear itself automatically when the current is reduced, but it is exacerbated with certain front and rear light models. Unfortunately the issue is intrinsic in ASI's motor controller and not something that can be solved via the harness.  If this will be an issue to you, we recommend getting a Cycle Analyst based kit instead. 

Display doesn't work, always says ERR30 or 30H: This means that the display is not successfully communicating with the motor controller. The most common reason is that the controller was not configured for display communications, as outlined in this video and in section 6 of the controller manual. If the controller is setup for PORT2 display and was previously working, then it is possible that the communication port either on the display or the controller has been damaged which can happen from high voltage exposure.

 

Speed reading works but is way off: The speed shown on the display is totally independent of the vehicle speed reported by your motor controller. The motor controller communicates to the display the time for one full wheel revolution and the display in turn uses this information to calculate the speed. Be sure to set the wheel size in the display itself and be sure that the settings in the motor controller for the #poles and speed pulses per revolution are correct. 

Speed is OK when motoring, but shows 0 when coasting: This means that you have a freewheeling geared hub motor, but either have the wheel speed sensor source in the controller configured for "Hall A" or the number of wheel speed pulses is set to zero. Both of those will force the controller to report motor speed as opposed to wheel speed. Be sure to set the wheel speed sensor source to "Brake2" and have your wheel speed pulses per rotation set to the number of magnets in your hub speed sensor. If you have a geared motor without an internal speedometer, then getting a speed signal while coasting will require custom wiring. You can splice into your L1019 or Z910 controller wiring and hook up an external speedometer sensor and spoke magnet to the white signal wire and have speed pulses get to the controller that way, but it won't be pretty. 

I have a 29" wheel and Speed always shows zero on the 750C display, but watts still works: There was a totally inexplicable bug in the firmware on our first shipment of the ATP 750C displays that caused the speed to always be zero when a 29" rim was selected. If you simply select the closest 28" rim it will show speed fine and be close enough for all intents and purposes. This bug has since been fixed as of 2025 and is no longer an issue.

My Amps and Watts are showing lower than settings: The ASI controllers with the 6.025 and earlier firmware incorrectly scale the amperage communicated over the KM5s protocol such that it displays 82.5% of the actual amperage and watts. So if you see 500 watts on the display, your actual power consumption from the battery is 606 watts.  This discrepancy may be fixed in a future firmware release from ASI as they are now aware of this bug. If you want precise amps, watts, and amp-hour accumulation, we recommend getting a Cycle Analyst based setup. 

 

Where to Purchase

The simpleharness is included with any of our kits and by itself on our store page.