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2.7 Grid Heater System

Type: Cold-start air intake heater

Model: Grid Heater Relay

Part Number: Cummins 5467024

Manufacturer: Cummins

Mounting: Engine bay near intake manifold

Power Source: START battery+ direct (via fusible link, 40-80A) — ⚠️ current unverified1

Control: Direct ECM control (pins 46/21)

Specifications

Spec Value
Type Cold-start air intake heater
Relay part number Cummins 5467024
Coil control ECM pins 46/21 (~0.5–1A)
Element current 40–80A (design estimate)1
Duty cycle 3–5 s during cold start (ECM-controlled)
Protection Integrated fusible link
Ground START battery- or NEGATIVE bus

Wiring Summary

Two-Stage Design: ECM pins 46/21 (1A) → relay coil → relay switches high current (40-80A) directly from battery to element.

flowchart LR
    ECM["Cummins ECM<br/>Pins 46/21"]
    RELAY["Grid Heater Relay<br/>Cummins 5467024"]
    BATT["START battery+<br/>(Direct Connection)"]
    GND["START battery-"]
    ELEMENT["Grid Heater Element<br/>40-80A"]

    ECM -->|"~1A coil control"| RELAY
    BATT -->|"Fusible Link<br/>40-80A"| RELAY
    RELAY -->|"40-80A switched"| ELEMENT
    ELEMENT --> GND

    style ECM fill:#d1d5db,color:#000
    style RELAY fill:#d1d5db,color:#000
    style BATT fill:#ffd93d,color:#000
    style GND fill:#ffd93d,color:#000
    style ELEMENT fill:#d1d5db,color:#000

Power Distribution

Direct ECM control (no PMU passthrough) and direct battery connection (no CONSTANT bus) — the ECM has better real-time engine temperature data than an external controller, and skipping PMU frees a PMU output slot. The brief high-current pulse (40-80A, 3-5s) doesn't justify bus-bar routing; the integrated fusible link is adequate protection. See Standards Exceptions for the full no-CB justification.

Outstanding Items

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  1. ⚠️ UNVERIFIED. Cummins does not publish a current draw for grid-heater part 5467024 on the R2.8 (spec flyer 5410825 / install guide 5504137 give no amperage); commonly-cited 95-110A figures are for Dodge/Ram 5.9/6.7 heaters, not this part (checked 2026-05-30). The 40-80A / 80A element values are engineering estimates — confirm by element-resistance measurement during install (already tracked as a Verification item). ↩↩