Duramax Diesels Forum Truck of the Week
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Old 03-10-2020, 01:47 PM
hotrod-z28 hotrod-z28 is offline
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Default Engine injectors losing electrical power.

Here's the thing, it does it randomly cold or hot, idling or running down the road. The injectors 2,4,6,7 are losing power and also getting a p2146 code. While trying to check it out I unplugged the lower main harness plug while it was running, course it died, then plugged it back in and proceeded to clear codes. Starts back up and runs fine for a short time or doesn't do it again until the next trip. I keep my scanner in the truck just in case. While checking it again I found a wire on the upper plug that was broken, so I fixed it, from what I can tell it is the wire going to the boost sensor. Upon trying to start it after fixing the wire, it would not turn over, checking fuses it had blown the ECM fuse, replaced it and it blew again, I cut that wire I had just fixed and replaced the fuse and it started.
Question: is the two related or two separate issues, I've been researching this from the internet to repair manuals and have come here hoping someone might of had the same or similar issues. The truck has 255,000 miles on it but engine still runs like when I bought at 40,000.
Any suggestions and help would be greatly appreciated. '03 LB7

Last edited by hotrod-z28; 03-10-2020 at 02:50 PM.
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Old 03-10-2020, 02:37 PM
gmac32 gmac32 is offline
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Year?
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Old 03-10-2020, 02:38 PM
gmac32 gmac32 is offline
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Check the ficm harness for rubbing on the aluminum bracket of the ficm
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Old 03-10-2020, 02:52 PM
hotrod-z28 hotrod-z28 is offline
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Default 03 lb7

'03 lb7
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Old 03-10-2020, 04:35 PM
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2004LB7 2004LB7 is offline
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Did the injectors get replaced not long ago, like 10k mikes or so? Maybe one of the injector harness fasteners has come loose. Not too uncommon if not torqued right
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Old 03-10-2020, 05:56 PM
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Moved to LB7 section. FICM wiring rub-thru by the mounting bracket would be my guess, but then it could be loose connections if the injectors had just been replaced, too.
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Old 03-10-2020, 09:12 PM
hotrod-z28 hotrod-z28 is offline
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I changed the injectors at 216,000, I have 255,000 now. I went ahead and took apart all of the plugs and cleaned them, including the FICM plugs. I also check the grounds, so we'll see if that does it

Last edited by hotrod-z28; 03-10-2020 at 09:17 PM.
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Old 03-11-2020, 05:58 AM
KyleC4 KyleC4 is offline
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So I take it you fixed the MAP sensor wire that was rubber through and grounding out? You said you kept blowing the ECM fuse so you cut the wire you just fixed.....so is it fixed now or just cut? A grounded circuit is not good. May want to follow that and figure where it’s shorted to ground that’s causing that fuse to blow consistently unless you have then ignore what I said.
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