ECM Code EO40: Open PSPS Circuit: Action:

ECM turns on SERVICE ENGINE SOON light. The power steering pressure switch is normally closed and opens with power steering pressure. The power steering pressure switch receives 12 volts from 10-amp solenoid fuse on circuit No. 639, and sends 12-volt signal to ECM on circuit No. 816.

When high power steering pressures occur, switch contacts are opened by power steering oil pressure and circuit No. 816 voltage is read by ECM as zero volts.

ECM uses power steering switch input to extend ISC when high power steering loads occur to help maintain a stable idle speed.