The Cummins ISM code 392 manual is a 5-page diagnostic PDF for the engine brake supply circuit on the ISM CM570 (1999–2002) engine. It documents the engine brake supply circuit that the electronic control module (ECM) drives to enable the engine brakes under set operating conditions.
Cummins ISM code 392 document details
| Brand | Cummins |
| Model coverage | ISM CM570 (1999–2002) |
| System / group | Engine brake supply circuit — DTCs |
| DTC number | 392 |
| PID / SPN | S029 / 1073 |
| FMI | 11/11 |
| Warning lamp | YELLOW |
| Pages | 5 |
| File format | |
| Language | English |
Document table of contents
- Circuit description and component location
- Shop talk on circuit-2 short to ground
- Actuator harness and ECM pin inspection
- 8-pin connector and pin-44 resistance test
Applicable truck models
This procedure applies to the ISM CM570 (1999–2002) engine and the shared CM570 fuel-system platform found in on-highway trucks. The same fault-code logic is carried across related CM570 engine families of that era. For engine identification and factory service references, see the manufacturer at the Cummins official website.
Who needs this Cummins ISM code 392 manual
The document places the engine brakes under the valve cover and notes the ECM enables them only under certain operating conditions. The listed cause for this fault is a short circuit to ground on ECM engine brake circuit 2. The steps inspect the actuator harness and ECM connector pins for corrosion, bent pins, moisture and missing seals, flush contacts with electrical contact cleaner Part Number 3824510, then disconnect the 8-pin engine brake connector and measure the resistance from pin 44 of the actuator harness.
This guide suits diesel technicians and workshop owners who face a fault on engine brake circuit 2 and need the 8-pin connector and pin-44 resistance measurement. It reads as fault code 392 troubleshooting steps for the engine brake supply circuit, keeping the diagnosis ordered and evidence-based.
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