Code EI78 - Power Steering Pressure Circuit: Notes

The power steering switch is normally closed and opens with high power steering pressure. During normal driving, the power steering switch receives 12 volts from the 10A solenoid fuse on circuit No. 639B, and sends the 12-volt signal to ECM on circuit No. 495. When high power steering pressures occur, the switch opens and circuit No. 495 voltage is read by ECM as zero (0) volts.

The ECM uses power steering input to extend the ISC motor when high power steering pressures occurs at low speeds, such as parking maneuvers.

1. The INPUT TEST "EI78" must be performed with the engine running.
2. Status "Stay Hi" means that switch is not opening with high pressure or that circuit No. 495 is shorted to voltage.
3. Status "Stays Lo" means that ECM never receives a 12-volt signal on circuit No. 495.
4. Remove and replace the ECM "J2 (C/D)" connector, and ensure it is latched.