Volvo Electric Power Steering Pump Control

CANBUS
Written By Brian Bourne

Overview

Control a Volvo Electric Power Steering Pump via CAN using specific messages for keep alive, speed control, and monitoring pump status.

This can be implemented via any microcontroller in the vehicle. We recently used an ECUMaster PMU-16 to adjust the assist based on the vehicle speed.

Keep Alive Message

  • Overview: This must be sent to the pump to keep it alive.  2Hz is fine.  Counter must cycle thru 4 values per below.  Remaining bytes remain fixed.

  • CAN ID: 0x1AE0092C (Extended)

  • Frequency: ~2 Hz

  • Sample Bytes: {<counter>, 0x00, 0x22, 0xE0, 0x41, 0x90, 0x00, 0x00}

  • <counter> Cycles through 0x00, 0x40, 0x80, 0xC0 for each subsequent message.

Speed Control Message

  • Overview: This message contains the PWM for how much assist is provided, basically this impacts pump speed.  Sending at a 50hz interval works also, though 70hz is factory.  The first 6 bytes are fixed and the final value is a 16bit value that ranges from 0 (fastest) to 6000 (least assist).

  • CAN ID: 0x2104136 (Extended)

  • Frequency: ~70 Hz

  • Sample Bytes: {0xBB, 0x00, 0x3F, 0xFF, 0x06, 0xE0, <speed>, <speed>}

  • <speed> Big-endian encoded PWM-derived value (0 for max assist, up to 6000 for min assist).

Pump Status Message

  • Overview: This message comes from the pump and can be ignored or used to ensure the pump is alive.  The heartbeat values never change.

  • CAN ID: 0x1B200002 (Extended)

  • Frequency: ~12 Hz

  • Sample Bytes: {0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x0F, 0x71}

  • Bytes: Fixed values representing the status of the pump.

Implementing Control

Optionally, wait to see heartbeat from pump before sending keepalive and speed.  You generally want to increase assist as the speed drops to parking lot speed and reduce assist as you approach highway speeds.

Brian Bourne
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