Note On Intermittents

Display PCM parameter P.0.1. Manipulate TP sensor wiring and connectors. Watch for TP sensor valve to jump or skip. Enter output cycling and manipulate ISC wiring and connectors. Watch for ISC to stop cycling. Enter diagnostics, and observe throttle switch status light (OFF). Check for binding throttle linkage and weak throttle return spring. If status light flashes, check circuit No. 427 for intermittent open. Verify minimum idle air RPM, ISC and TP sensor are set to specification.

Fig 1: PCM Code E30 Schematic - Idle Speed Control Ckt. Problem

Courtesy of GENERAL MOTORS CORP.

Fig 2: PCM Code E30 Flow Chart - Idle Speed Control Ckt. Problem

Courtesy of GENERAL MOTORS CORP.