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Home >> GMC >> 1991 >> Value Van 7.4 N >> Repair and Diagnosis >> External Pages >> Different car >> Section 31 (Engine Controls - Tests W/Codes - 3.3L CNG) >> Self-Diagnostic Tests >> Test NTC-2A - Checking Secondary Ignition & Timing

Test NTC-2A - Checking Secondary Ignition & Timing

WARNING: This page is about a different car, the 1995 Plymouth Voyager, 1995 Plymouth Grand Voyager, 1995 Dodge Grand Caravan, and 1995 Dodge Caravan. However, it is still accessible from the selected car via links, so may be relevant.
  1. Turn ignition off. Connect a suitable engine analyzer to engine. Start engine and operate at idle. If engine will not idle, maintain a constant RPM more than idle. Set scope to read display or parade pattern. Following equipment manufacturer's procedure for pattern analysis, analyze secondary ignition pattern. If secondary ignition pattern is not okay, repair indicated component in secondary ignition system. Perform TEST VER-2.
  2. If secondary ignition pattern is okay , remove lower spark plug wires one at a time from ignition coil while observing secondary k/volts line. If open circuit secondary voltage is less than 25 k/volts, replace electronic ignition coil. Perform TEST VER-2. If open circuit secondary voltage is more than 25 k/volts, reinstall spark plug wire(s). Go to next step.
  3. Ensure engine operating temperature is more than 180°F. Using scan tool, read total timing advance. Increase engine speed to 2000 RPM. If timing advance does not change when RPM is increased, replace Powertrain Control Module (PCM). Perform TEST VER-2. If timing advance changes when RPM is increased, secondary ignition and timing are okay. Test is complete.
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