Cummins ISM Code 339 is the official Cummins fault code troubleshooting PDF that documents the idle shutdown vehicle accessory/ignition bus relay circuit on ISM CM570 (1999-02) engines. This 4-page reference from the Cummins service literature explains the circuit, the likely causes behind the yellow warning lamp, and the step-by-step checks a technician follows to confirm the repair.
Official document details
| Brand | Cummins |
|---|---|
| Model coverage | ISM CM570, ISX CM570 and Signature CM570 (1999-02) |
| System / Group | Idle Shutdown Vehicle Accessory/Ignition Bus Relay Circuit (DTCs) |
| Fault code | Code 339 · PID S087 · SPN 1267 · FMI 4/4 |
| Warning lamp | Yellow |
| Year / Revision | Copyright 2017 |
| Pages | 4 |
| File size | 0.3 MB |
| Format | |
| Language | English |
Document table of contents
- Circuit description
- Component location
- Shop talk – possible causes
- Troubleshooting steps
- Fault code verification and clearing
Cummins ISM Code 339 troubleshooting summary
The idle shutdown vehicle accessory/ignition bus relay is a device used to control vehicle accessories or ignition bus leads. Vehicle accessories or ignition bus leads will be shut down when the ECM shuts down the engine for excessive idle time. The location of the relay is dependent on the OEM. The manual walks through 8 labelled troubleshooting steps that inspect connectors and pins, measure circuit resistance, and verify the fault code is inactive after the repair.
Possible causes listed in the Shop Talk section include:
- Check the starter solenoid positive (+) terminal for a loose
- Low voltage can be caused by a short circuit to ground, a
- Inspect the engine block to chassis ground wire. It should
Referenced Cummins service tools and part numbers: 3824510.
Applicable truck models
This procedure applies to Cummins ISM CM570, ISX CM570 and Signature CM570 engines built in the 1999-02 range, as used in Class 8 highway trucks. Always confirm the exact engine dataplate before servicing. Full engine specifications and dealer support are available on the Cummins official website.
Who needs this Cummins ISM Code 339 manual
Heavy-duty diesel technicians, fleet service managers and independent workshop owners diagnosing a Code 339 on the idle shutdown vehicle accessory/ignition bus relay circuit rely on this document to follow the manufacturer procedure instead of guessing at parts. Because Code 339 shares its troubleshooting logic with the ISX CM570 and Signature CM570 platforms, a single PDF supports several Cummins engine families in the same workshop.
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