Add handoff.md for in-cab pickup

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_016yT89n4zR4qbrySoSiEyZs
2026-06-29 19:18:09 -04:00
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+# Handoff — ford-obd / 6.0 Power Stroke no-start
+
+Pick-up notes for diagnosing the truck in the cab. Repo: `git.jpaul.io/justin/ford-obd` (private).
+
+## TL;DR — what to do at the truck
+1. CH340 ELM327 adapter → OBD port (under dash, driver side).
+2. Key to **RUN** (not ACC). Engine off is fine for reading codes.
+3. On the Windows laptop, in the repo folder: **double-click `RUN_OBD.bat`**
+   (or `python obd_reader.py`). If no port found: `python obd_reader.py COM5`.
+4. Read the codes + the no-start triage it prints. Write the codes down.
+5. To erase codes after reading: `python obd_reader.py COM5 --clear` (it asks you to type `CLEAR`).
+
+## Hardware confirmed
+- Adapter chip: **QinHeng CH340** (`USB 1a86:7523`), ELM327 **v1.5** clone.
+- Working **baud: 38400** (default in the tool). If you get garbage, try `9600`.
+- It's an `AT@2 = ?` clone (no stored serial) — normal, works fine for generic OBD-II.
+
+## What the tool does / doesn't
+- DOES: read stored/pending/permanent codes, decode them (6.0 codes flagged as
+  no-start suspects), clear codes (`--clear`), show battery voltage + key live PIDs.
+- DOESN'T: Ford-enhanced diesel PIDs — **ICP, FICM main/sync voltage, IPR%**.
+  Those need FORScan. For those numbers tonight, measure at the FICM with a meter.
+
+## 6.0 no-start priority checklist (from the triage)
+The 6.0 needs, to fire: **good batteries → FICM ~48V → ICP ~500 psi → fuel → cam/crank signal.**
+1. **Batteries** — both. Weak battery → FICM won't boost → no injector fire. Load test;
+   ~12.5V+ at rest, watch it while cranking.
+2. **FICM voltage** while cranking (~48V). #1 6.0 cold no-start cause. <45V is suspect.
+3. **ICP** (injection control pressure) ~500 psi to fire. Leaks: STC fitting, oil rail
+   O-rings, high-pressure oil hoses, IPR/HPOP.
+4. **Fuel** — HFCM lift pump priming, fuel filters, water-in-fuel.
+5. **CMP/CKP sensors** — failed cam sensor = crank, no-start (codes P0340/P0341, P0335/P0336).
+6. **Glow plugs/relay** if cold (won't stop start, but hard start).
+
+## Code-driven branches the tool will hint at
+- `P0335/P0336/P0340/P0341/P0344` → cam/crank sensor path.
+- `P0611/P1316` or `P02xx`/`P026x` injector codes → FICM / injector path.
+- `P0087/P0148/P0191` → fuel pressure (low-side + high-side oil).
+- `U0100/U0073/P0606` → module comms / PCM.
+
+## Status of this session's work
+- Tool built + tested against the real adapter (init, all 3 DTC modes, live PIDs, clear flow).
+- DTC parser unit-tested incl. a fixed bug: legacy ISO/PWM multi-frame responses repeat the
+  `43` header (was producing phantom codes) — fixed + regression-tested.
+- Pushed to `git.jpaul.io/justin/ford-obd`, branch `main`. Files: `obd_reader.py`,
+  `RUN_OBD.bat`, `README.md`, `README.txt`, `handoff.md`.
+
+## To resume with Claude from the cab
+Mention: "6.0 Power Stroke no-start, using the ford-obd tool (git.jpaul.io/justin/ford-obd)".
+Then **paste the tool's full output** (codes + live values). Useful to also say: cranks vs.
+no-crank, hot vs. cold, what changed before it died, and FICM/ICP readings if you metered them.
+
+## Open follow-ups (when off the truck)
+- FORScan from the CyanLabs mirror once forscan.org is back, for ICP/FICM/IPR PIDs on the same adapter.
+- Optional: add a few known Ford Mode-22 enhanced PIDs to the tool (verify PID numbers first).