LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Cadillac >> 1987 >> Seville >> Repair and Diagnosis >> Engine Performance >> System >> DFI ECM Tests W/Codes >> Diagnosis & Testing >> Hard/Intermittent Code EO30 - Idle Speed Control CKT >> Notes On Intermittents
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Notes On Intermittents

Display ECM parameter code "ED01". Manipulate TPS wiring and connectors. Watch for TPS 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. Check for binding throttle linkage or weak throttle return spring.

Verify minimum air RPM, ISC and TPS are set to specifications. A code "EO30" may be stored along with a code "EO19", SHORTED FUEL PUMP CIRCUIT. If code "EO30" no longer appears after code "EO19" has been corrected, do not investigate any further. The voltage on fuel pump feedback circuit made ECM improperly test code "EO30".

Fig 1: Hard or Intermittent Trouble Code E030 - ISC Ckt
G4371
Fig 2: Hard or Intermittent Trouble Code E030 - ISC Ckt (1 of 4)
GB0020734
Fig 3: Hard or Intermittent Trouble Code E030 - ISC Ckt (2 of 4)
GB0020735
Fig 4: Hard or Intermittent Trouble Code E030 - ISC Ckt (3 of 4)
GB0020736
Fig 5: Hard or Intermittent Trouble Code E030 - ISC Ckt (4 of 4)
GB0020737
Fig 6: Schematic for Hard Trouble Code E030
G201983