The Cummins ISX code 3734 manual is a 12-page PDF that documents fault code 3734, the crankcase breather filter heater circuit fault set for voltage below normal or shorted to low source. It explains that the crankcase breather heater keeps the breather filter housing from freezing, that the ECM supplies 12 VDC when heating is commanded, and that this code is set when the heater signal circuit is shorted to ground. 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 | 3734 (PID P102, SPN 862, FMI 4) |
| Warning lamp | Amber |
| Pages | 12 |
| File size | 0.2 MB |
| Format | |
| Language | English |
Document table of contents
- Fault code 3734 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 crankcase breather heater is mounted to the crankcase breather filter housing. The reported cause is low signal voltage at the heater circuit; while active the crankcase breather heater is disabled. For engine data and authorised service, visit the Cummins official website.
Who needs this Cummins ISX code 3734 manual
Heavy-duty diesel technicians, fleet workshops and owner-operators reach for this manual when fault code 3734 is logged and the amber warning lamp is on. It gives a technician the checks needed to confirm a short to ground in the breather-heater circuit before replacing the heater or harness.
Download the ISX code 3734 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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