Opel Electric Power Steering Column
The Vauxhall/Opel electric power steering column has been retrofitted to various cars in the EV conversion world for quite a while.
Wiring
There's 2 connectors, one for the power, Red 6mm2 is the 12v power, though a 50a fuse and the other negative, again 6mm2.
The other connector has the signals, all 0.5mm2 wires.
Blue/Red Trace - ABS Speed input Red/White Trace - Engine Multi Timer Input Black - Ignition(5a fuse) Green - Engine RPM Brown/White Trace - diagnostic output.
Usage[1][2]
The Vauxhall Corsa EPS column varies it’s steering assistance depending on steering wheel torque input and to a certain extent speed. The EPAS ECU contains 3 assistance maps – Max, Med and Min, which are switched between depending on the speed signal.
Maximum 0-18mph Medium 18-45mph Minimum 45+mph
Speed Signal
The speed signal is a 0-12v square wave. If this signal is lost, it reverts to a default assistance map.
- TODO* Add details of signal to map
Engine Multi Timer Input
This is a 12v signal, supposed to be given 10 seconds after the engine has started, but some forums say it can be ignition switched or left floating.
Engine RPM
This is required to get assistance, a 0-12v square, 55Hz to 30kHz, 20% to 50% duty cycle.
ABS input
Without an ABS input, the column will offer maximum assistance. The higher the frequency input, the less assistance the rack will offer. Again 12v square shaped waveform.