This Cummins 3734 fault code document is a troubleshooting PDF for a crankcase breather filter heater circuit with voltage below normal or a short to low source. It explains the fault logic, lamp response, clearing conditions, and guided electrical checks used with INSITE™ electronic service tool.
Official Cummins 3734 fault code document details
| Brand | Cummins |
|---|---|
| Model coverage | ISX11.9 CM2250 / ISX15 CM2250; file metadata also lists ISB6.7 CM2250 (2010-12) |
| System/Group | DTCs; crankcase breather filter heater circuit |
| Publication no. | Bulletin numbers referenced: 4022250, 2883445 |
| Year/Revision | Last Modified: 11-Jun-2010; troubleshooting section Last Modified: 20-Jul-2010 |
| Pages | 12 |
| File size | 0.2 MB |
| Format | |
| Language | English |
Document table of contents
- Overview
- Circuit Description
- Component Location
- Conditions for Running the Diagnostics
- Conditions for Setting the Fault Codes
- FAULT CODE 3734 – Crankcase Breather Filter Heater Circuit – Voltage Below Normal or Shorted to Low Source
- Action Taken When the Fault Code is Active
- Conditions for Clearing the Fault Code
- Shop Talk
- Associated Procedures
- Troubleshooting Steps
- Guided Step 1 – Check the fault codes
- Guided Step 2 – Check the crankcase breather heater and circuit
- Guided Step 3 – Check the ECM and engine harness
- Guided Step 4 – Check ECM calibration and clear fault codes
Applicable truck models
This procedure applies to Cummins engines identified in the document as ISX11.9 CM2250 and ISX15 CM2250, with related associated procedures for Electronic Control Module (ECM), ECM Calibration Code, and Engine Wiring Harness. The file metadata also classifies the document under Cummins ISB6.7 CM2250 (2010-12) DTCs, but the extracted procedure text names the ISX11.9 CM2250 and ISX15 CM2250 coverage. For manufacturer information, visit Cummins official website.
Who needs this Cummins 3734 fault code manual
Workshop technicians, fleet mechanics, and diagnostic specialists need this Cummins 3734 fault code manual when an amber CHECK ENGINE lamp is linked to SPN 862 FMI 4. The procedure supports connector inspection, resistance measurement, harness short checks, ECM calibration review, and repair validation.
The diagnostic states that the ECM supplies 12-VDC to the breather heater when heating is commanded, and that the crankcase breather heater is mounted to the crankcase breather filter housing. The fault is set when the ECM detects the heater signal circuit shorted to ground; the effect listed is none on performance, while the heater is disabled when the code is active. Possible causes listed in Shop Talk are a short circuit to ground in the crankcase breather heater circuit or a malfunctioning ECM.
The guided steps start by reading active fault codes with INSITE™ electronic service tool. The document then directs inspection of the crankcase breather heater connector and engine harness connector pins for loose connectors, corrosion, bent or broken pins, pushed back or expanded pins, moisture, damaged seals, debris, shell damage, wire insulation damage, and damaged locking tabs. Resistance checks include measuring from the crankcase breather heater SIGNAL pin to ground, checking heater resistance between SIGNAL and RETURN, testing the engine harness ECM connector for pin-to-ground shorts, and checking for pin-to-pin shorts against other ECM connector pins.
If damaged connections are found, the procedure calls for cleaning, connector or pin repair, or engine harness repair using Procedure 019-043. If heater short tests fail, it directs replacement of the crankcase breather heater according to the OEM service manual. If the harness and connector checks do not resolve the fault, the document moves to inactive fault confirmation, possible ECM replacement authorization, ECM calibration revision review under Procedure 019-032, and final fault clearing after operating the engine within the listed clearing conditions.
Full PDF available in the DiagTechPro manuals library, free account required to download.
Related manuals library
Sản phẩm liên quan cho hãng này
Cùng brand theo taxonomy hiện có trong catalog WooCommerce.
Cummins INSITE 9.3 – The Essential Diagnostic Tool for Cummins Engines
Cummins Calterm Version 5.16 – Advanced ECM Control and Precision Tuning for Cummins Engines
Cummins InCal CE – The Calibration and Configuration Tool for Cummins Engines
