Misfire, rough running, surge, chuggle, and possible MIL/SES light on. LLY
#1
06-28-2014, 11:54 AM
Misfire, rough running, surge, chuggle, and possible MIL/SES light on. LLY
this is for the lly engines, whenever there is a Misfire, rough running, surge, chuggle, and possible MIL/SES light on.
Typically there is a wiring harness issue and injectors often don't have to be changed even when there is a high injector balance rate showing. If you were to follow the actual diagnostic steps for these codes P1223, P1226, P1229, P1232, P1235,
P1238, P1241 or P1244 and get through all the steps you could very possibly end up replacing a FICM that is still good.
so before you go adress those codes physically be sure to read this bulletin.
Typically there is a wiring harness issue and injectors often don't have to be changed even when there is a high injector balance rate showing. If you were to follow the actual diagnostic steps for these codes P1223, P1226, P1229, P1232, P1235,
P1238, P1241 or P1244 and get through all the steps you could very possibly end up replacing a FICM that is still good.
so before you go adress those codes physically be sure to read this bulletin.
Models: 2004-2005 Chevrolet Kodiak, Silverado
2004-2005 GMC Sierra, Topkick
with 6.6 Engine (VIN 2 - RPO LLY)
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.
2004-2005 GMC Sierra, Topkick
with 6.6 Engine (VIN 2 - RPO LLY)
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 repair information diagnostics.
2. If all repair information 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 repair information wire
repair procedures. Insulate the harness with wiring conduit or a suitable material so
the wires will not chafe again.
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 repair information 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 repair information wire repair
procedures. Insulate the harness with wiring conduit or a suitable material so the
wires will not chafe again.
Source: GM Preliminary Information Bulletin #PIP3394E – (02/01/2008)
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 repair information wire repair
procedures. Insulate the harness with wiring conduit or a suitable material so the
wires will not chafe again.
