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Makes 🢒 Chevrolet 🢒 2005 🢒 Chevrolet C-Series Medium Duty Truck C6/C7/C8 🢒 Bulletins 🢒 Duramax Diesel Injector Driver Codes - keywords ECM FICM P0300 P1223 P1226 P1229 P1232 P1235 P1238 P1241 P1244 chafe circuit chuggle connector miss misfire surge wire

Duramax Diesel Injector Driver Codes - keywords ECM FICM P0300 P1223 P1226 P1229 P1232 P1235 P1238 P1241 P1244 chafe circuit chuggle connector miss misfire surge wire

Subject:Duramax Diesel Injector Driver Codes

Models:2004-2005 Chevrolet Kodiak, Silverado
2004-2005 GMC Sierra, Topkick
with 6.6 Engine (VIN 2 - RPO LLY)


This PI was superceded to include GMT560 trucks. Please discard PIP3394D.

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Condition/Concern:

Misfire, rough running, surge, chuggle, and possible MIL/SES light on.

Recommendation/Instructions:

Do not replace fuel injectors for trouble codes P1223, P1226, P1229, P1232, P1235, P1238, P1241 or P1244. When these codes are set, there is either a wiring concern between the Engine Control Module (ECM) and the Fuel Injection Control module (FICM), or a concern with the control module itself, (ECM/FICM). If there is a concern on the injector driver circuits (open, short to ground or high resistance), it is possible to have a high injector balance rate.

  1. Diagnose all injector driver codes using the current SI diagnostics.
  2. If all SI diagnostics are inconclusive, inspect for wire chafes at the Fuel Injector Control Module (FICM) wiring harness brace. The wiring harness brace is located 4 to 6 inches away from the FICM connectors. The wiring harness is nylon tied to the wiring harness brace. It may be necessary to remove the nylon tie to inspect the harness. Repair any wire chafes following SI wire repair procedures. Insulate the harness with wiring conduit or a suitable material so the wires will not chafe again.
  3. Also inspect the C107 connector for wire chafes. The C107 connector is found above the left (driver side) rocker cover. The wiring harness may relax and lay on top of the C107 support brace. This support brace is located right below the C107 connector. Repair any wire chafes following SI wire repair procedures. Insulate the harness with wiring conduit or a suitable material so the wires will not chafe again.
  4. Use GMVIS to check the build date of the vehicle. If the vehicle is a 2005 light duty C/K truck, built between 3/03/05 and 3/15/05, refer to Inventory Upgrade Bulletin number 05054. Inventory Upgrade Bulletin 05054 describes a possible coolant leak from the Coolant Surge Tank. The coolant may wick into the engine wiring harness and induce injector driver codes.

Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.