Hey everyone,
I recently picked up a 2018 G21 with the PCM H5 and ran into a serious issue on my first time out — four simultaneous DTC codes (2261, 2270, 2276, 2279) for Direct Injector High Side Short to Ground on cylinders 1, 4, 6, and 7. Engine ran rough and I had to limp back to the dock at 1200 RPM.
During the diagnostic process, one of the most frustrating things was the complete lack of publicly available wiring information for the H5/H6. No pinout diagrams, no ECM connector maps — all dealer-only through Diacom. I called PCM and was able to track down the official PCM wiring schematics and am attaching them to this post as a PDF for anyone who needs them. These cover the full H5 and H6 (5.3L / 6.2L DI) engines including injectors, ignition coils, sensors, throttle body, relays, fuel pump, O2 sensors, grounds, and power circuits.
I also took those diagrams and built an interactive web tool that makes them easier to navigate. Click any component and it highlights the ECM pins associated with it. Click any pin on the ECM connector grid and it tells you exactly what it controls and what circuit it belongs to. No more guessing or scrolling through pages of schematics.
https://pmc-h5-h6-wiring-tool.netlify.app/
A few notes:
— The attached PDF contains the original PCM wiring diagrams (DI_NA_PCM001 through PCM016) — use these as your source of truth
— The web tool is built from those same diagrams and is meant to make them faster to navigate in the field
— Built for the H5 and H6 specifically, but may also apply to other PCM DI engines sharing the same E92 ECM architecture — Centurion and Supreme owners with the same platform may find this useful too
— Works on desktop and mobile
Hope this saves someone else hours of head-scratching. If you spot any errors or have additional diagram pages to contribute, let me know and I'll update the tool.
Nathan
I recently picked up a 2018 G21 with the PCM H5 and ran into a serious issue on my first time out — four simultaneous DTC codes (2261, 2270, 2276, 2279) for Direct Injector High Side Short to Ground on cylinders 1, 4, 6, and 7. Engine ran rough and I had to limp back to the dock at 1200 RPM.
During the diagnostic process, one of the most frustrating things was the complete lack of publicly available wiring information for the H5/H6. No pinout diagrams, no ECM connector maps — all dealer-only through Diacom. I called PCM and was able to track down the official PCM wiring schematics and am attaching them to this post as a PDF for anyone who needs them. These cover the full H5 and H6 (5.3L / 6.2L DI) engines including injectors, ignition coils, sensors, throttle body, relays, fuel pump, O2 sensors, grounds, and power circuits.
I also took those diagrams and built an interactive web tool that makes them easier to navigate. Click any component and it highlights the ECM pins associated with it. Click any pin on the ECM connector grid and it tells you exactly what it controls and what circuit it belongs to. No more guessing or scrolling through pages of schematics.
https://pmc-h5-h6-wiring-tool.netlify.app/
A few notes:
— The attached PDF contains the original PCM wiring diagrams (DI_NA_PCM001 through PCM016) — use these as your source of truth
— The web tool is built from those same diagrams and is meant to make them faster to navigate in the field
— Built for the H5 and H6 specifically, but may also apply to other PCM DI engines sharing the same E92 ECM architecture — Centurion and Supreme owners with the same platform may find this useful too
— Works on desktop and mobile
Hope this saves someone else hours of head-scratching. If you spot any errors or have additional diagram pages to contribute, let me know and I'll update the tool.
Nathan
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