Notes On Intermittents

Look for binding throttle linkage due to TV, cruise, throttle cables, TPS installed improperly, or throttle shaft binding. Check for proper throttle return spring and throttle return spring installation.

Probe ECM D15 to ground with a voltmeter. Manipulate wiring and connectors at closed throttle and watch for 5.0 volts, indicating an open from D15 to ground. Manipulate wiring and connectors at open throttle and watch for zero (0) volts, indicating short to ground on circuit No. 427.

Fig 1: Code E172 - Throttle Switch Circuit

Fig 2: Code E172 - Throttle Switch Circuit (1 of 2)

Fig 3: Code E172 - Throttle Switch Circuit (2 of 2)

Fig 4: Schematic for Hard Trouble Code EI72