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Home >> GMC >> 1991 >> Value Van 7.4 N >> Repair and Diagnosis >> External Pages >> Different car >> Section 4 (Engine Controls - System/Component Tests) >> Ignition System >> Timing Control Systems (C-4 & C-5) >> C-5, Electronic Spark Control (ESC) Circuit (4.3L Turbo & Vehicles With 4L80-E Transmission)

C-5, Electronic Spark Control (ESC) Circuit (4.3L Turbo & Vehicles With 4L80-E Transmission)

WARNING: This page does not describe the selected car, but rather 35 other vehicles, including the 1992 Pontiac Trans Sport, 1992 Oldsmobile Silhouette, 1992 Oldsmobile Bravada, 1992 GMC Yukon, and 1992 GMC Vandura Special. However, it is still accessible from the selected car via links, so may be relevant.
  1. An open or short circuit on the ESC wire to the ECM will set a related trouble code. A false detonation signal will not cause ECM to set a code.
  2. If a scan tester is available, connect it to the ALDL connector. Tap on engine next to knock sensor and note "knock" parameter. Knock should be indicated on scan tester.
  3. If a scan tester is not available, connect tachometer to engine. Start engine and hold RPM above idle. Using a metal object, tap on engine close to knock sensor. A noticeable decrease in engine RPM should occur. If no RPM decrease occurred, check knock sensor to ECM circuit.
  4. On vehicles equipped with automatic transmission, it may be necessary to place transmission in Drive for timing change to occur. See KNOCK SENSOR  under ENGINE SENSORS & SWITCHES.
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