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Home >> GMC >> 1987 >> Forward Control 6.2 J, Automatic, 400/M40 >> Repair and Diagnosis >> External Pages >> Different car >> Section 21 (Engine Controls - Basic Testing - Gasoline) >> C-4, Basic Ignition System Checks >> HEI-Est Distributor >> Spark
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HEI-Est Distributor: Spark

WARNING: This page does not describe the selected car, but rather 10 other vehicles, including the 1994 GMC Vandura Special, 1994 GMC Vandura, 1994 GMC Rally Camper Special, 1994 GMC Rally, and 1994 GMC Forward Control. However, it is still accessible from the selected car via links, so may be relevant.
  1. If factory tachometer is connected to ignition coil tachometer terminal, disconnect it before performing tests. When removing spark plug wire from spark plug, twist and pull on boot. DO NOT  pull on wire.
  2. Using Spark Tester (ST-125), check for spark at coil wire (if applicable) and at each spark plug wire. Check spark plug wire resistance on suspect wires. Resistance should not be greater than 30,000 ohms.
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