Duramax Diesels Forum Truck of the Week
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Old 06-15-2018, 03:02 PM
Choptop Choptop is offline
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Default 2003 lb7 no start

Hello, first timer here! Need some help 2003 lb7 all stock but does have fass150 lift pump installed by previous owner. Today I went to start the truck a and it fired for a second then shut off. Checked for codes none present. Data list shows 3500-3800 rail pressure while cranking over. I know I'm going to get the don't do that but I disconnected the glow plugs and hit it with ether and she fired but still won't run. With no codes not sure where to go next
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Old 06-15-2018, 03:09 PM
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Moved over to the LB7 section.
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Old 06-15-2018, 04:05 PM
Choptop Choptop is offline
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Ok after fooling with more I finally got a U1800 loss of communication with ficm tested all fuse they ok. Anyone have test procedure for U1800 code?
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Old 06-15-2018, 05:32 PM
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duramax on fire duramax on fire is offline
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Did you check the ficm connectors. Unplug them and plug them back in. Maybe wiggle them.

And the connectors that connect the ficm to the injector harness.
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Old 06-15-2018, 05:54 PM
Choptop Choptop is offline
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Checked every connection at ficm and emc. Now for the weird part while going back through every fuse in the block I touched the SIR fuse with my power probe and no power with key on. I wiggled it and heard the door chime go off and probe lit up. Got it truck hit the switch and it fired up! Reset code and after 20 times cranking up no codes! Wth would the SIR have to do with it? I'll keep trying tomorrow but for now it starts every time
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Old 06-15-2018, 07:19 PM
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Robby Avery Robby Avery is offline
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No sure how the sir fuse made it start and run but be careful doing so if you back feed the sir to much voltage via powerprobe you could blow the airbags just a disclaimer. I always test sir components and circuits with sir disabled so as to not blow bags just for warning you. You could disconnect batteries and remove the fuse block cover and shield use a 8mm or 10mm and removed connectors from fuse block and inspect the terminals to see if you have corroded terminals or terminals shorting together. Where was the fass tapped in for key on power? Also it's never a good idea to use ether once you use it most diesels I've seen become crack baby's and require it every time for starting. lb7's are higher compression engines than other rpo dmaxs which makes it much harder on them. Have you addressed the ficm connectors as mentioned in an earlier post?
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2006 Chevy 2500HD LBZ Duramax Summit White CCSB Tan (neutral) leather LT3 pkg w/sunroof OEM bra 4x4, ISSPRO EV, ATS Twin CP3's, Built Allison, Eaton E-locker front stock G80 rear, Kennedy Twin pump filter combo kit, Snow Perf Stage 2 w/m injection, 4in to 5in banks tip, HM Big K&N, Mickey Thompson Baja Claw TTC 315/75/16 on stock rims, Rancho RS9000XL, Fabtech HD TR, Cognito P&I Brace kit, DD/Puller/Work Truck



2002 Chevy 2500HD LB7 Duramax Summit White CCSB Grey (neutral) leather LT3 pkg OEM bra 4x4, Kennedy Twin Pump Filter Combo Kit, ISSPRO EV, PPE Boost Valve, DTS Built Allison, MikeL Cooler, ATS Billet Flexplate, DTS 3in DS IC pipe, Bill's 5in CAI (White), Big K&N, 4in to 7in black stack, Mickey Thompson Baja Claw TTC 315/75/16 on stock rims, Cognito P&I Brace kit, Sleeves, Energy Sway bar Kit, DD/Puller/Work truck



Special Thanks: (David) DTS, (Guy) Socal Diesel, (Nick & crew) DuramaxTuner, (Dan) PPE, (John) Kennedy Diesel, (Tony) All Season
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Old 06-16-2018, 04:46 PM
Choptop Choptop is offline
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Hey Robby, I only use the power probe for audible check never use it on any computer systems. The fass was put in the ign. 1 fuse when I bought it but I removed it and tied it into the ign inside the vehicle. I don't like those fuse taps. It is still starting so I'll keep up to date if anything changes.
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Old 06-16-2018, 06:31 PM
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Robby Avery Robby Avery is offline
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Ok that works just let us know if any other problems arise we are here to help
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2006 Chevy 2500HD LBZ Duramax Summit White CCSB Tan (neutral) leather LT3 pkg w/sunroof OEM bra 4x4, ISSPRO EV, ATS Twin CP3's, Built Allison, Eaton E-locker front stock G80 rear, Kennedy Twin pump filter combo kit, Snow Perf Stage 2 w/m injection, 4in to 5in banks tip, HM Big K&N, Mickey Thompson Baja Claw TTC 315/75/16 on stock rims, Rancho RS9000XL, Fabtech HD TR, Cognito P&I Brace kit, DD/Puller/Work Truck



2002 Chevy 2500HD LB7 Duramax Summit White CCSB Grey (neutral) leather LT3 pkg OEM bra 4x4, Kennedy Twin Pump Filter Combo Kit, ISSPRO EV, PPE Boost Valve, DTS Built Allison, MikeL Cooler, ATS Billet Flexplate, DTS 3in DS IC pipe, Bill's 5in CAI (White), Big K&N, 4in to 7in black stack, Mickey Thompson Baja Claw TTC 315/75/16 on stock rims, Cognito P&I Brace kit, Sleeves, Energy Sway bar Kit, DD/Puller/Work truck



Special Thanks: (David) DTS, (Guy) Socal Diesel, (Nick & crew) DuramaxTuner, (Dan) PPE, (John) Kennedy Diesel, (Tony) All Season
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