Note On Intermittents

Manipulate ECT sensor wiring, ECT sensor connector and PCM connector while observing PCM Data PD04. If engine coolant temperature jumps from a normal reading to -36.4°F (-38°C) or less, repair intermittent open in circuit No. 410 or 808. Remove and reconnect both ECT sensor and PCM connectors and retest before replacing any components. If wiring and connectors are okay, substitute a known good ECT sensor and retest.

Fig 1: Code P015 Schematic, Open Engine Coolant Temperature (ECT) Sensor

Courtesy of GENERAL MOTORS CORP.

Fig 2: Code P015 Diagnostic Flow Chart, Open ECT Sensor

Courtesy of GENERAL MOTORS CORP.