Note: - This does not apply to the Atom and Monsoon ECUs

An ISC Stepper Motor must be wired to Aux 5, Aux 6, Aux 7 and Aux 8.

When using an ISC Stepper, the ECUs power supply should be wired for ECU Hold Power as shown in Figure 6.2. This will allow the ECUs Hold Power function to be taken advantage of. Using ECU Hold Power allows the ECU to reset the stepper motor after key off. This avoids extended cranking periods caused by resetting the stepper at key on.

The diagram below shows a schematic of a four-terminal stepper motor. Note that there are two coils. Use an ohmmeter to pair the terminals with a common coil. Aux 5 and 6 must be connected to the terminals for one coil, while Aux 7 and 8 must be connected to the terminals for the other coil. If it is found that the stepper motor runs in the opposite direction to that expected, reverse the wiring to Aux 5 and Aux 6.

 

Note: Stepper motors with a winding resistance of less than 20 ohms are not recommended, because of the higher current draw, these stepper motors are at risk of over heating and open or short circuiting windings. The vast majority of stepper motors have winding resistances higher than 20 ohms.