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Discussion Starter #1 (Edited)
My #7 injector stopped firing and OBDII posted the P0279 code - INJ Cylinder #7 injector circuit low.

I would like to go ahead and replace the wiring harness but thought I would check here before ordering. What are the possibilities it is something in the FICM or actual injector rather than the harness? I purchased a Swamps FICM back in 2012 and it has not given me any issues (so far).

I'd hate to purchase and install the harness only to discover that is not the problem. I physically inspected all of the pasenger side of the harness and some of the driver's side. Some is buried under the turbo and my Bullet Proof EGR cooler hoses so I did not inspect that visually.

Thanks!

P.S. Is is hard on the engine to do some light driving with one cylinder out of comission?
 

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If I were to guess I would say no. DTC P0279 is a "circuit low" code which means an injector circuit is electrically open. 6.0L injector harness faults are almost always shorts to ground because of the way they fail - early build engines had many harness problems that resulted in a recall and revisions to the harness. A short would produce a "circuit high" code, a P0280 for injector #7 for example. FICM failures most commonly cause multiple injector fault codes simultaneously and since you only have the one code for injector #7 I would strongly suggest diagnosing the injector itself. There are two coils: an open coil and a close coil. The resistances need to be measured to determine of one has failed. In this scenario if I HAD to guess without performing any diagnostics I would suspect the injector before the FICM or the harness.
 

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Discussion Starter #3
Much obliged!

I was thinking an "open" due to excess chafing but that would likely be a "short" before the wear was bad enough to become open.

I will check the injector itself. I should have swapped #5 injector connector with #7 and run the buzz test as that would have eliminated any cable questions.

Have a good weekend!
 
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