LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> GMC >> 1993 >> Forward Control 4.3 Z, Automatic >> Repair and Diagnosis >> External Pages >> Different car >> Section 153 (Cruise Control System) >> Self-Diagnostic Tests >> Test SC-2A - Checking Speed Control On/Off Switch
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Test SC-2A - Checking Speed Control On/Off Switch

WARNING: This page is about a different car, the 1995 Plymouth Voyager, 1995 Plymouth Grand Voyager, 1995 Dodge Grand Caravan, 1995 Dodge Caravan, and 1995 Chrysler Town & Country. However, it is still accessible from the selected car via links, so may be relevant.
  1. Turn ignition off. Disconnect speed control switch connector. Check connector for damaged, pushed out or miswired terminals. Repair as necessary. Perform TEST SC-VER  . If connector is okay, check voltage of speed control switch connector, switch signal circuit (Brown/Red wire) using DRB in voltmeter mode.
  2. If voltage is less than 10 volts, repair short to ground in Brown/Red wire. Perform TEST SC-VER  . If voltage is greater than 10 volts, turn ignition on. Using DRB in voltmeter mode, check voltage of speed control switch connector, fused ignition switch output circuit (Yellow/Red wire). If voltage is less than 10 volts, repair open Yellow/Red wire. Perform TEST SC-VER  .
  3. If voltage is greater than 10 volts, connect a jumper wire between speed control switch connector, fused ignition switch output circuit (Yellow/Red wire) and speed control switch signal circuit (Brown/Red wire).
  4. Using DRB, read speed control switch voltage. If DRB displays 5.00V SET, replace speed control switch. Perform TEST SC-VER  . If DRB does not display 5.00V SET, turn ignition off.
  5. Disconnect Powertrain Control Module (PCM) connector. Check connector for damaged, pushed out or miswired terminals. Repair as necessary. Perform TEST SC-VER  . If connector is okay, turn ignition on.
  6. Using an external ohmmeter, check resistance of speed control switch signal circuit between speed control switch connector (Brown/Red wire) and PCM connector terminal No. 23 (Red/Light Green wire). If resistance is greater than 5 ohms, repair open Brown/Red wire or Red/Light Green wire. Perform TEST SC-VER  . If resistance is less than 5 ohms, replace PCM. Perform TEST SC-VER  .