Test STI - Self-Test Input

NOTE: Enter this test only when Super Star II tester displays STO LO or VOM displays zero volt.

CIRCUIT PIN IDENTIFICATION

Circuit	Breakout Box Pin No.	PCM Pin	Wire Color
STI	48	1L	Red/White

1) Check System Integrity Visually check all wiring and connectors for evidence of damage, shorting or looseness. If fault is found, repair as necessary. If no fault is found, go to next step.

2) Check For Open STI Wire Turn ignition off. Install breakout box, leaving PCM disconnected. Measure resistance between STI test pin at breakout box and PCM STI terminal at Data Link Connector (DLC). See Fig 1. If resistance is less than 5 ohms, go to next step. If resistance is at least 5 ohms, repair open PCM STI wire between PCM and DLC.

Fig 1: Identifying Data Link Connector Terminals

Courtesy of FORD MOTOR CO.

3) Check For Short In PCM STI Wire Ensure ignition is off, breakout box is installed and PCM disconnected. Measure resistance between ground and STI test pin at breakout box. If resistance is more than 10,000 ohms, go to TEST STO. If resistance is 10,000 ohms or less, repair short to ground in PCM STI wire.