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Home >> GMC >> 1991 >> Value Van 7.4 N >> Repair and Diagnosis >> External Pages >> Different car >> Section 43 (Engine Controls - Tests W/Codes - 8.0L) >> Self-Diagnostic Tests >> Test TC-27A - Ignition Coil #5 Primary Circuit (DTC 43)

Test TC-27A - Ignition Coil #5 Primary Circuit (DTC 43)

WARNING: This page is about a different car, the 1995 Dodge Pickup and 1995 Dodge Cab & Chassis. However, it is still accessible from the selected car via links, so may be relevant.
NOTE: For circuit and connector terminal identification, see CONNECTOR IDENTIFICATION  . For wiring diagrams, see WIRING DIAGRAMS  section at the end of this article.
CAUTION: When checking for spark, Powertrain Control Module (PCM) damage may occur if spark plug cable is held more than 1/4" away from ground.
  1. Using scan tool, erase trouble codes. Turn ignition off. Disconnect spark plug cable at No. 2 spark plug. Insert an insulated screwdriver in spark plug cable terminal. Hold screwdriver within 1/4" of ground.
    NOTE: When checking for spark, consider one or two sparks as a no-spark condition.
  2. Turn ignition on with engine off. Using scan tool, actuate ignition coil No. 5, while watching for spark. If good spark does not occur, go to step 6). If good spark occurs, condition required to set code is not present at this time. Go to next step.
  3. IGNITION COIL #5 PRIMARY CIRCUIT trouble code sets when Powertrain Control Module (PCM) does not see peak current reached. Possible causes are: open ignition coil No. 5 primary circuit, open or shorted driver circuit (Dark Green/Gray wire), open Auto Shutdown (ASD) relay output circuit (Dark Green/Orange wire) or failed PCM.
  4. Inspect all related wiring and connectors and repair as necessary. Perform TEST VER-2. If no problems are found in wiring and connectors, go to next step.
  5. Start engine. Wiggle wiring harness from front coil pack to PCM. If spark becomes erratic or stops, repair harness where wiggling causes problem to occur. Perform TEST VER-2. If spark does not become erratic or stop, see INACTIVE DTC CONDITION  . Perform TEST VER-2.
  6. Turn ignition off. Disconnect front ignition coil connector. Check connector for damaged, pushed-out, or miswired terminals. Repair as necessary. Perform TEST VER-2. If connector is okay, go to next step.
  7. Turn ignition on. Using scan tool, actuate ignition coil No. 5. Using scan tool in voltmeter mode, check voltage on front ignition coil connector, Auto Shutdown (ASD) relay output circuit (Dark Green/Orange wire). If voltage is less than 10 volts, repair open Dark Green/Orange wire. Perform TEST VER-2.
  8. If voltage is more than 10 volts, turn ignition off. Disconnect Powertrain Control Module (PCM) connector. Using scan tool in ohmmeter mode, check resistance of front ignition coil connector, No. 5 primary circuit (Dark Green/Gray wire). If resistance is less than 5 ohms, repair short to ground in Dark Green/Gray wire. Perform TEST VER-2.
  9. If resistance is more than 5 ohms, connect a jumper wire between front ignition coil connector, No. 5 primary circuit (Dark Green/Gray wire) and engine ground. Using scan tool in ohmmeter mode, check resistance of PCM connector terminal No. 18, No. 5 ignition coil primary circuit (Dark Green/Gray wire). If resistance is more than 5 ohms, repair open Dark Green/Gray wire. Perform TEST VER-2.
  10. If resistance is less than 5 ohms, using an external ohmmeter, check resistance of ignition coil No. 5 primary circuit. Put one ohmmeter lead on front ignition coil, cylinders No. 2 and 3 terminal, and other ohmmeter lead on front ignition coil, ASD relay output terminal. See Figure . If resistance is more than 2 ohms, replace front ignition coil. Perform TEST VER-2. If resistance is less than 2 ohms, replace PCM. Perform TEST VER-2.
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