The Cummins ISX code 3736 manual is a 10-page PDF that documents fault code 3736, the aftertreatment diesel exhaust fluid controller fault reported as root cause not known. It explains that the DEF controller is the central control for the SCR dosing system and that this code is set when the ECM sends an unexpected J1939 message that the controller cannot interpret. The procedure is credited to TruckFaultCodes.com and covers the circuit description, component location and full troubleshooting steps.
Official document details
| Brand | Cummins |
| Model coverage | Cummins ISX11.9 CM2250 and ISX12 CM2250 (2010-12) engines |
| System / group | ISX11.9 CM2250 (2010-12) / DTCs |
| Fault code | 3736 (PID S027, SPN 3360, FMI 11) |
| Warning lamp | Amber |
| Pages | 10 |
| File size | 0.2 MB |
| Format | |
| Language | English |
Document table of contents
- Fault code 3736 description
- Circuit description and ECM operation
- Component location
- Shop talk and possible causes
- Step-by-step troubleshooting flow
Applicable truck models
This diagnostic applies to Cummins ISX11.9 CM2250 and ISX12 CM2250 (2010-12) engines. The DEF controller is typically mounted to the vehicle frame or a rigid bracket by the OEM, so refer to the OEM service manual. The effect is that diesel exhaust fluid injection into the aftertreatment system is disabled. For engine data and authorised service, visit the Cummins official website.
Who needs this Cummins ISX code 3736 manual
Heavy-duty diesel technicians, fleet workshops and owner-operators reach for this manual when fault code 3736 is logged and the amber warning lamp is on. It helps a technician diagnose data-link communication problems between the ECM and the DEF controller before parts are replaced.
Download the ISX code 3736 PDF
The complete procedure, wiring detail and step tables are available in the DiagTechPro manuals library; a free account is required to download the PDF. Keep it alongside the related ISX11.9 CM2250 fault-code sheets listed below.
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