NO_COM - Display V1/V1.1

The "NO_COM" error on a Stromer S-Pedelec V1 or V1.1 means that there is no communication between the display and the motor/controller. "NO_COM" stands for "No Communication".

This is a serious problem, as the motor (and therefore the electrical support) cannot function if the display does not receive and send data from the controller in the motor.

Here are the most common causes and what you can do:

1. problems with the wiring or plug connections:

• Damaged 5-pole sensor cable: This is the main cable that connects the display to the motor and transmits the communication signals. A cable break, crushing or damage to this cable is a very common cause of "NO_COM". Check the entire cable for visible damage.
• Loose or corroded plug connections: The connectors of the 5-pin cable (both on the display and on the motor) may become loose or corroded. Carefully disconnect the connections, clean them (using contact spray if necessary) and firmly reconnect them.
• "Wicked cable" (extension cable): Some V1/V1.1 models have an extension cable between the motor and the display. A defect in this cable can also lead to communication problems.

2. defect in the motor / controller:

• Controller error in the motor: In the Stromer V1/V1.1 models, the controller (the power electronics) is installed directly in the motor. These controllers were prone to heat problems and other defects in older models. If the controller in the motor no longer functions properly, it cannot send or receive communication signals, which leads to "NO_COM". This is a common and often costly cause.
• Moisture in the engine: Penetrating moisture can damage the electronics in the motor and cause communication errors.
• Faulty software/firmware in the controller: Although less common, damaged or faulty firmware on the motor controller can lead to communication problems.

3. defect in the display:

• The display itself may be defective and not process or send the communication signals correctly. However, this is less common than a problem with the wiring or the motor.
• A defective NPN transistor in the display has been cited as the cause of "NO_COM" in some cases.

4. battery problems (indirect):

• Although "NO_COM" is primarily a communication problem and differs from "NO_BAT" (no battery voltage), extreme battery problems (e.g. deep discharge or a defective BMS that completely interrupts the power supply) can result in the motor/controller not being supplied with power and therefore no communication being possible. It is possible that the "NO_COM" error sometimes occurs together with "NO_BATT" or in quick succession.

What to do with "NO_COM"?

1. Check plug connections: This is the simplest and first step. Disconnect all accessible plugs, especially those of the display cable and the cable coming out of the motor, and plug them back together again. Clean the contacts.
2. Check cable routing: Carefully walk along the display cable from the handlebars to the motor and look for visible damage (kinks, crushing, chafing).
3. Connect the display directly to the motor (if possible): On some Stromer V1/V1.1 models, there is an additional plug connection in the area of the chain stay that could make it possible to connect the display directly to the cable coming from the motor and thus eliminate the "wicked cable" (extension in the frame) as a source of error. If the error then disappears, the problem lies with the extension cable.
4. Check battery voltage: Ensure that the battery is sufficiently charged and supplies the correct voltage.
5. Contact your Stromer dealer: As the "NO_COM" error in the V1/V1.1 models often indicates a defect in the motor/controller, it is usually essential to visit an authorized Stromer specialist dealer. They have the special diagnostic tools to localize the fault precisely and carry out a repair (often motor replacement). Attempts to open the motor yourself are complex and not recommended, as they invalidate the warranty and can cause further damage if handled incorrectly.

It is important to note that the V1/V1.1 models in particular were more prone to such faults due to the electronics integrated in the motor. Newer Stromer models have moved the power electronics to a separate control unit (MCU) outside the motor to minimize heat problems.