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GM Upfitter bulletins — the factory rulebook

GM publishes Upfitter Integration technical bulletins for anyone modifying a BrightDrop — no-drill zones, high-voltage procedures, the factory-blessed way to tap 12 V power. These are the manufacturer's own rules for exactly the kind of work this build does, and several of them override guesses the plan used to carry. All nine BrightDrop-applicable bulletins are archived below (Drive copies + GM originals), and the section after the table translates them into build-plan rules. Archived 2026-09-06 from gmupfitter.com.

The bulletin library

Drive folder with all nine PDFs: EVLife / GM Upfitter Bulletins →

#	Subject	Last revised	Why it matters here	Copies
191c	Cautionary — NO Drill / Air Bag Zones, Zevo cargo van	Sep 2024	The single most important document for the shell phase. Maps side-impact, roof-rail and driver airbag deploy zones plus the no-drill zones for the 400/600, and warns: never cut an orange HV cable.	Drive → GM →
190b	Battery negative cable disconnection & connection — Zevo 600	Sep 2024	The mandatory prelude to every electrical step: the 12 V negative disconnect procedure, the high-voltage service lockout (HVSL), the battery-maintenance-mode trap, and the battery monitor module you must not disturb.	Drive → GM →
188d	Adding ignition & battery powered 12 V circuits — Zevo vans	Sep 2024	GM's official way to add fused ignition-switched and constant-battery 12 V provisions with proper grounding (9 N·m ground torque, Yazaki terminal P/N 7116-4781-02). Requires the 190b disconnect first.	Drive → GM →
196b	Adding upfitter switches (RPO 9L7) — Zevo vans	Sep 2024	MY24+ vans carry two fused upfitter power feeds; 9L7 provisions give 2 × 30 A relay-controlled circuits, a 10 A run-mode circuit, and blunt-cut wires by the park brake — with the wire colors and circuit numbers documented.	Drive → GM →
189	EV high-voltage safety (all GM EVs)	Apr 2023	The PPE and procedure baseline: Class 0 gloves, CAT III meters only, the one-hand rule, orange = high voltage. The reason the electrical sign-off gate exists.	Drive → GM →
198c	High-voltage disabling / enabling — EV models	Sep 2024	Index of the official HV disable/enable procedures for the 2024 electric vans (and other GM EVs), with the instruction to read 189 first.	Drive → GM →
197b	BrightDrop exterior panel dimensions	Sep 2024	Factory dimensions for the side panels, roof, front, rear and roll-up door — published for wraps/decals, useful here for the solar layout and any exterior planning. 400 vs 600 differ only in cargo-side and roof panel length.	Drive → GM →
202	Backup alarm installation recommendations	Jun 2024	Written for Silverado HD but describes our van's exact symptom: a backup alarm wired to the reverse-lamp circuit sounds on fob presses and entry/exit because perimeter lighting energizes the reverse lamps. Two GM-sanctioned fixes.	Drive → GM →
192c	Delivery inspection training video and forms	Sep 2024	Upfitter delivery-inspection process — the takeaway for a private owner is to photo-document the van's condition on delivery day, because in-transit damage claims die without it.	Drive → GM →

Local copies also live in the research repo under evlife/reference/gm-upfitter-bulletins/. Several bulletins are mostly diagrams — the Drive PDFs are the authority; the notes below are what the diagrams and text mean for this build.

What the bulletins change in the build plan

1. Shell & mounting — 191c is now a hard gate input

No hole gets drilled without a 191c overlay. The Zevo has mapped airbag deploy zones (side-impact, roof-rail, driver) and no-drill zones, different for 400/600 and FWD/AWD. Every rivnut, track, window and gland location in the measure + freeze phase gets checked against the MY23+ 600 diagrams before it goes on the template.
The diagrams are explicitly reference-only. GM says so in the bulletin: for precise design/mounting locations, submit a Math Data (CAD) request via the gmupfitter contact form. That request should go in during the measurement phase — it's free and removes all guessing about what's behind a panel.
Never cut an orange cable. Stated in capitals in 191c. The AWD 600 adds a rear drive unit and its HV cabling — floor penetrations near the rear axle need the extra caution.
Impact sensors and antennas are mapped too. Mounting hardware over or near them is a no — locations come with the same Math Data request.
197b panel dimensions feed the roof plan. The factory roof/side panel dims are the sanity check for the solar rack layout and shade sizing before anything is cut.

2. Electrical — the factory procedures replace improvisation

Every electrical work session starts with 190b. Ignition off, key out. Check 12 V voltage first — 13.5 V or above means Battery Maintenance Mode is active and the HV charger is energizing the 12 V cables; wait for it to stop before touching the negative cable. Then engage the high-voltage service lockout (ON→OFF, pin it with a tie-strap or padlock), and only then work.
Don't touch the battery monitor module. Disconnect the negative cable at the module stud only — unplugging the module or pulling it off the battery post forces a 4-hour relearn. Ground fasteners re-torque to 9 N·m / 80 lb-in.
12 V accessory power comes from the factory provisions, not from tapped circuits. 188d documents the blessed battery + ignition circuit add; 196b documents the 9L7 upfitter provisions — 2 × 30 A fused relay-controlled outputs fed from the 12 V battery (isolated from the HV system by design), a 10 A run-mode circuit, and relay control inputs, all on blunt-cut wires near the park brake (circuits 10716/10717/10721/10731/10732). The house system's van-side needs — DC-DC enable keyed to RUN, the Bosch ES4 / induction interlock signal, door-state triggers — ride these circuits.
HV work is professional-only, formally. 189's PPE list (certified Class 0 1000 V gloves with leather protectors, CAT III meter, one-hand rule, no AC-powered test gear on the isolated HV system) is the factory statement of what the plan's licensed-electrical-sign-off gate already assumed. Nothing in this build should ever open the orange system — 198c's disable/enable procedures exist for the professionals who might.

3. The backup-alarm chime — solved by bulletin 202

The symptom on our van — alarm sounding with the roll-up open or in reverse, silenced by a fob lock/unlock — matches 202's description exactly: a backup alarm wired to the reverse-lamp circuit fires whenever perimeter lighting or fob acknowledgment energizes those lamps, not just in reverse.
GM's fix #1: dealer reprograms the BCM with the SFW backup-alarm calibration, which permanently disables perimeter lighting; the alarm then only sounds in actual reverse. (Admin fee + labor.)
GM's fix #2 (the DIY one): an ignition-controlled relay between the reverse-lamp circuit and the alarm, so the alarm can only sound with ignition on + reverse engaged. For the conversion the simpler variant applies: the fleet backup alarm can be unplugged entirely — a private camper has no OSHA fleet requirement for it.

New standing rule — baked into the manualBefore any panel, floor or roof penetration is finalized: check 191c zones, and if the location is within guessing distance of an airbag zone, sensor, antenna or harness run, hold the hole until GM Math Data confirms clearance. Before any electrical session: run the 190b disconnect procedure, including the 13.5 V maintenance-mode check. All van-side 12 V taps go through 188d/196b provisions only.

Study notes distilled 2026-09-06 from the nine PDFs above; the research-repo copy of this analysis lives at evlife/research/gm-upfitter-bulletins-study.md.