EPS Diagnosis General Description
The P/S system in this vehicle is controlled by the P/S control module. The P/S control module has an on-board
diagnostic system which detects a malfunction in this system. When diagnosing troubles, be sure to have full
understanding of the outline of "On-Board Diagnostic System Description" and each item in "Precautions in
Diagnosing Troubles", and then execute diagnosis according to "EPS System Check".
On-Board Diagnostic System Description
The P/S control module performs the on-board diagnosis (self-diagnosis) on the system and operates the "EPS"
warning light (1) as follows.
• The "EPS" warning light lights when the ignition switch is turned to ON position (but the engine at stop) regardless
of the condition of the P/S control system. This is only to check if the "EPS" warning light is operated properly.
• If the areas monitored by the P/S control module is free from any trouble after the engine start (while engine is
running), the "EPS" warning light turns OFF.
• When the P/S control module detects a trouble which has occurred in the monitored areas the "EPS" warning light
comes ON while the engine is running to warn the driver of such occurrence of the trouble and at the same time it
stores the exact trouble area in memory inside of the P/S control module.
A "Driving Cycle" consists of engine startup and engine shutoff.
3 Driving Cycles Detection Logic
The malfunction detected in the first and second driving cycle is stored in P/S control module memory (in the form of
pending DTC) but the "EPS" warning light does not light at these time. It lights up at the third detection of same
malfunction also in the next driving cycle.
Power Assisted Steering System: