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5.6 Keyless Ignition System

Modern push-button ignition for the Cummins R2.8 + 8HP70 build. Replaces the factory keyswitch entirely. Single dash button starts and stops the engine. Boomerang Bullet 230 RFID provides theft deterrence. State machine runs on the PMU24.

Architecture

Type: RFID-enabled push-button start/stop with diesel-specific interlocks

Anti-theft: Boomerang Bullet 230 (RFID fob required to enable)

State Machine: PMU24 firmware (logic in 04-pmu-programming.md)

Crank Interlocks: Brake pedal + Turbolamik P/N + engine-running lockout

Emergency Bypass: Hidden hardwired toggle (get-home mode)

Components

Boomerang Bullet 230 (RFID Immobilizer)

Specification Value
Type RFID transponder + fob
Detection Range 3-6 ft
Output Single transistor output (12V when fob in range)
Power 12V CONSTANT (so fob can be detected key-off)
Mounting Under dash, near driver position
Product Page Boomerang Bullet 230

Dash Push-Button

Specification Value
Type Momentary, normally open, illuminated
Diameter 19mm or 22mm panel mount
Illumination LED, driven by PMU (state feedback)
Mounting Dash, within easy reach from driver seat
Part TBD (Otto P9-113121 or equivalent)

ECM Ignition Relay

Specification Value
Type Automotive SPST, 30/40A
Coil 12V DC, ~150 mA draw
Contacts Switches Cummins ECM 12V supply
Mounting Engine bay, near ECM
Part TBD (Hella H41730011 or Bosch 0332019150)

P/N Interlock Relay

Specification Value
Type Automotive SPST, 30A
Coil 12V DC, driven by Turbolamik P/N aux output
Contacts NO; in series with crank circuit
Mounting Engine bay, near Cole Hersee 24213
Part TBD

Engine-Running Lockout Relay

Prevents Cole Hersee from energizing while the engine is running, even if the start button is pressed with brake + P/N held. Protects the starter from Bendix engagement against a spinning flywheel.

Specification Value
Type Automotive SPST, 30A
Coil 12V DC, driven by alternator output (~14V when running)
Coil Trigger Simple diode + zener filter on alternator B+ tap (>13V threshold)
Contacts NC; opens when engine running
Mounting Engine bay, near Cole Hersee 24213
Part TBD

State Machine

Current State Trigger Action New State
OFF Fob detected + button press Assert OUT24 (ECM powered) RUN
OFF Fob detected + button + brake + P/N Assert OUT24 → hardware crank chain closes CRANK
CRANK J1939 RPM > 500 (engine running) Engine-running relay opens, crank disengages RUN
RUN Button press (with or without brake) De-assert OUT24, ECM loses power, engine off OFF
Any Hold button > 3 sec Force OFF (emergency) OFF
Any Fob lost while moving (RPM > 0) Stay in current state, log alarm unchanged
OFF Button press, fob NOT detected No action, optional alarm chirp OFF

Fob-lost behavior: If the fob leaves range while driving, the PMU does not kill the engine — only blocks re-start at the next OFF cycle. Modern-car convention; prevents stranding on dead fob battery.

Wiring

PMU24 I/O (new)

PMU Channel Function Source Destination Notes
In 4 Boomerang fob present Bullet 230 transistor output PMU In 4 12V active when fob in range
In 5 Push button Dash button (NO contact) PMU In 5 Pulled up; goes high on press
In 6 Turbolamik P/N Turbolamik P/N aux output PMU In 6 12V active when in P or N
Out 24 Ignition Authorize PMU OUT24 ECM ignition relay + start circuit supply ~5A, switched by PMU logic

J1939 RPM is read via the existing CAN bus connection (PMU Inputs - CAN). No new wire needed for the engine-running input to the state machine.

Power & Control Wiring

Connection Wire Gauge Source Destination Notes
Boomerang power 18 AWG Critical Cabin PDU (CONSTANT) Bullet 230 +12V input ~50 mA standby; CONSTANT required
Boomerang ground 18 AWG Cabin ground bus Bullet 230 ground
Boomerang → PMU In 4 18 AWG Bullet 230 transistor output Firewall Pin (TBD) → PMU In 4 Cabin → Engine Bay
Push button signal 18 AWG Dash button NO contact Firewall Pin 15 → PMU In 5 Cabin → Engine Bay
Push button LED supply 22 AWG PMU OUT24 (or dedicated tap) Button LED+ Illuminates when ignition authorized
Button LED ground 22 AWG Button LED- Cabin ground bus
OUT24 → ECM relay coil 18 AWG PMU OUT24 ECM ignition relay coil+ Engine bay
OUT24 → crank supply 18 AWG PMU OUT24 Push button supply (cabin) Engine Bay → Cabin (firewall)
Start chain (cabin) 18 AWG Push button output (gated) Brake switch start tap Cabin
Start chain (firewall) 18 AWG Brake switch start tap Firewall Pin (TBD) → P/N relay Cabin → Engine Bay
P/N relay coil 18 AWG Turbolamik P/N aux output P/N interlock relay coil Engine bay
ER lockout coil 18 AWG Alternator B+ (via filter) Engine-running relay coil Engine bay; opens contacts when RPM up
Cole Hersee drive 16 AWG ER lockout relay NC output Cole Hersee 24213 coil+ Engine bay
Hidden bypass toggle 18 AWG Battery+ (via fuse) ECM ignition relay coil+ (parallel) Get-home mode, hidden under dash

Firewall Pin Assignments

Three pins are used by the keyless system. Pin 15 was reassigned from the prior P/N interlock placeholder (the P/N signal now stays in the engine bay since PMU and Turbolamik are co-located).

Pin Direction Signal Source Destination
15 Cabin → EB Push button signal Dash button NO PMU In 5
TBD Cabin → EB Boomerang fob present Bullet 230 output PMU In 4
TBD EB → Cabin OUT24 ignition supply PMU OUT24 Dash button supply
TBD Cabin → EB Gated start (post-brake) Brake switch output P/N relay contact

See Firewall Ingress for the full pin map.

Emergency Bypass

A hidden hardwired toggle (under dash, location TBD) bypasses the PMU and directly powers the ECM ignition relay coil from CONSTANT 12V via a 5A inline fuse. This provides a get-home mode if:

  • PMU24 firmware locks up or fails
  • Boomerang Bullet 230 fails or fob battery dies and PMU programming has no fallback
  • A CAN bus fault prevents the state machine from running

Bypass does NOT enable cranking — only ignition. Cranking still requires the full hardware interlock chain (brake + P/N + engine-running lockout). In bypass mode you can still start by holding the dash button if all hardware interlocks are intact.

Diesel Runaway Note

The Cummins R2.8 is a modern electronic common-rail diesel. Normal engine shutdown is achieved by cutting power to the ECM, which stops commanding the injectors. However, ECM-only kill does not stop a true runaway — if the engine is being fed oil, fuel, or hydrocarbon vapor from an external source, cutting ECM power does nothing.

This build provides independent mechanical protection: a Mishimoto catch can in the crankcase ventilation path (prevention) plus an AMOT 4261M air shutoff valve with dash-mounted manual cable (termination). See Diesel Runaway Protection for the full specification.

Outstanding Items

  • Select Boomerang Bullet 230 mounting location (under dash, near driver)
  • Select dash push-button part (Otto, Apem, Carling, etc.) - 19mm/22mm, illuminated, momentary NO
  • Select ECM ignition relay part (Hella/Bosch SPST 30-40A automotive)
  • Select P/N interlock relay part (SPST 30A automotive)
  • Select engine-running lockout relay part (SPST 30A, NC contacts)
  • Design alternator B+ voltage filter for engine-running relay coil drive (diode + zener + resistor)
  • Assign 3 new firewall HDP24 pin numbers (currently TBD): fob signal, OUT24 supply to cabin, gated start return
  • Determine hidden bypass toggle location and part
  • Confirm Turbolamik aux output channel can be configured for P/N (12V when in P or N)
  • Decide PMU output strategy: OUT24-only with engine-running lockout (current plan) vs. freeing OUT15 winch trigger for dedicated crank output
  • Write PMU24 state-machine logic in ECUMaster Light Client (see PMU Programming)