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Going The Distance - 2005 Chevy Silverado 2500HD

High-Mileage Duramax Diagnosis And Fix

Mike McGlothlin
Apr 1, 2013
Photographers: Mike McGlothlin
In light of Duramax engine number 1,500,000 recently rolling off the assembly line at Dmax Ltd., we thought we’d bring you a feel-good story about how these engines can literally run forever. Our candidate is an ’05 Chevy Silverado 2500HD that’s been worked since day one on a large farm. It’d been beaten and abused for nearly 390,000 miles and showed no signs of letting up until the farmhand behind the wheel realized the engine had developed a miss.
Photo 2/13   |   going The Distance 2005 Chevy Silverado 2500hd front Three Quarter
"“In all our years being around the Duramax, it’s become abundantly clear that they are built for the long haul.”"
When the high-mileage LLY showed up at Flynn’s Shop in Alexander, Illinois, to be repaired, the truck’s owner expected the worst: a bad injector, damaged piston, or a cylinder low on compression. Having owned LB7-powered trucks in the past, the owner was leaning toward it being a bad injector. But, with just a little more than an hour’s worth of troubleshooting, the technicians at Flynn’s diagnosed the real problem: an open circuit in the engine’s wiring harness. The truck was fixed in two hours.
Photo 3/13   |   After many years of service, this LLY Duramax had definitely earned its keep. Prior to this visit, the only major repair the ’05 Silverado ever needed was a water pump replacement—which all the Big Three diesel mills typically need somewhere between 100,000 and 200,000 miles.
P1241 Trouble Code = No Injector Replacement
Brought in for an intermittent, rough running engine and white smoke out the tailpipe, the truck was interfaced with a scan tool to check for DTCs. The P1241 code (highlighted) was the reason behind the engine’s misfire. This DTC means there is an electronic fault in the output circuit of injector number 7. Fortunately for the customer, a P1241 also means injector replacement isn’t needed. GM issued a TSB (technical service bulletin) for this code as well as several others, which states that the problem is either between the ECM and FICM (what drives the injectors), or the injector driver circuit is open, shorted to ground, or experiencing high resistance. Because the ECM monitors the fuel injection control module (FICM) on the Duramax, it will set a code if the desired state and the actual state of the injector control circuit don’t match (such as incorrect voltage being sent to an injector). Put simply, the number 7 injector wasn’t firing properly.
Photo 13/13   |   going The Distance 2005 Chevy Silverado 2500hd injector Circut Codes
All injector output circuit DTCs:
P1223 – Injector 1
P1226 – Injector 2
P1229 – Injector 3
P1232 – Injector 4
P1235 – Injector 5
P1238 – Injector 6
P1241 – Injector 7
P1244 – Injector 8

Sources

Flynn's Shop
Alexander, IL
217-478-3811

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