LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Toyota >> 1988 >> 4Runner Base, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Computer Control System >> Diagnosis & Testing >> Diagnosis
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Diagnosis & Testing: Diagnosis

  1. Ensure all engine systems NOT related to TCCS are fully operational. DO NOT  proceed with testing until all other problems have been repaired. Ensure fuses, fusible links and wire connectors are in good condition before diagnosing ECU.
  2. Enter diagnostic mode and record trouble codes. Exit diagnostic mode. If no trouble codes were displayed, proceed to appropriate DIAGNOSTIC CIRCUIT CHECK  charts. Follow instructions given there.
  3. If no trouble codes were displayed after performing diagnostic circuit check, perform voltage and resistance checks. See appropriate ECU PIN VOLTAGE TEST  chart in this article.
  4. If trouble codes are displayed, perform tests to confirm cause of malfunction which set the corresponding trouble code.
  5. After any repairs are made, clear trouble codes and perform diagnostic circuit check. Normal system operation code should be displayed if repair solved cause of malfunction.
scientia non olet · About LEMON Manuals