LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> GMC >> 1997 >> Forward Control 6.5 F >> Repair and Diagnosis >> External Pages >> Different car >> Section 39 (Engine Controls - System/Component Tests - 5.7L.) >> Ignition System >> Timing Control Systems (C-4 & C-5) >> Controller Module)
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Controller Module)

WARNING: This page does not describe the selected car, but rather 16 other vehicles, including the 1996 GMC Yukon, 1996 GMC Vandura Special, 1996 GMC Vandura, 1996 GMC Suburban, and 1996 GMC Savana Special. However, it is still accessible from the selected car via links, so may be relevant.
  1. An open or short circuit on ESC wire to ECM/PCM/VCM will cause a loss of 12-volt ESC controller signal. This will cause ECM/PCM/VCM to fully retard ignition timing.
  2. If a scan tester is available, connect tester to Data Link Connector (DLC). Using a metal object, 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, backprobe ECM/PCM/VCM knock sensor signal terminal with a DVOM. With engine idling, 8-12 volts should be present at this terminal. Using a metal object, tap on engine close to knock sensor. Voltage signal at ECM/PCM/VCM terminal should drop to zero volts, and return when knock signal ceases.
  4. If signal does not respond as described, check knock sensor-to-controller-signal. 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.
scientia non olet · About LEMON Manuals