2018 G21-Injector Short to Ground

[nathandantzler]

2018 G21 with PCM H5.

Bought the boat and took it out for the first time. Ran great for about 20 minutes, then suddenly started throwing these codes:

• DTC 2261

• DTC 2270

• DTC 2276

• DTC 2279


All are “Direct Injector High Side Short to Ground” on cylinders 1, 4, 6, and 7.

The engine runs very rough, but will occasionally spike back to normal RPMs and then go rough again. I had to limp it back to the dock at about 1200 RPM.

Has anyone seen this issue on the H5 before? Any advice before I start pulling the intake manifold to trace wiring?

Thanks!

[jpwhit]

Short to ground code really just means the high side of the injector isn't at the voltage expected. It doesn't actually have to be a short to ground. Given the pattern of which injectors are giving that code, I suspect it may be something like a fuse or relay on the power feed side of those injectors. Unfortunately, without a wiring diagram or being able to physically look at the engine, that's all the help I'm able to provide.

If I were diagnosing this further, I start with a meter or scope looking at the powered side of the injector wiring, and then tracing that wiring path to the voltage source. You can also check the injector that are working to see which wire is the powered side and which wire is the sink side wire going to the ECM. The way the ECM detects this code, is it watches the voltage of the sink side input on the ECM to see if the voltage rises when the sink FET is turned off.

[nathandantzler]

Thank you so much for taking the time to respond — this is exactly the kind of guidance I needed and really helps point me in the right direction.
Based on what you said about tracing the power feed side, my plan is to start with the fuses and relays first since that’s the most accessible starting point. If that doesn’t turn anything up, I’ll move on to pulling the intake manifold to get eyes on the injector sub-harnesses underneath. I know that’s a bigger job but it sounds like there’s no way around it if the fuses and relays check out clean.
One thing I did find while I was poking around — I pulled the ECM connectors and found what looks like green corrosion on one of the pins inside one of the connectors. I’m attaching a photo. I don’t know if that’s related or just a separate moisture issue, but it seemed worth mentioning given the symptoms. Curious if you think that could play a role in what I’m seeing.
I’ll report back once I’ve had a chance to dig in further. Really appreciate your help — this community is invaluable