This Cummins Fault 478 document is a troubleshooting procedure for Battery 2 Voltage above normal on the aftertreatment diesel exhaust fluid controller voltage supply circuit. It explains fault conditions, lamp behavior, DEF dosing effects, INSITE checks, harness inspection, voltage testing, alternator checks, ECM calibration review, and fault clearing.
Official Cummins Fault 478 document details
| Brand | Cummins |
|---|---|
| Model coverage | ISB6.7 CM2250 (2010-12); extract also lists ISX11.9 CM2250, ISC8.3 and ISL9 CM2250, ISX15 CM2250, ISF2.8 CM2220 AN, ISF3.8 CM2220 AN, GX CM2250, QSL9 CM2250, and QSB6.7 CM2250 in associated procedures. |
| System/Group | DTCs; Aftertreatment Diesel Exhaust Fluid Controller Voltage Supply Circuit |
| Publication no. | Not stated for the main file; associated bulletin numbers include 4022254 for ISB6.7 CM2250. |
| Year/Revision | Last Modified: 11-Jun-2010 and 05-Dec-2010 |
| Pages | 10 |
| 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
- 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 aftertreatment diesel exhaust fluid controller.
- Guided Step 3 – Check the alternator.
- Guided Step 4 – Check ECM calibration and clear fault codes.
Applicable truck models
This procedure applies to Cummins engine platforms listed in the document, including ISB6.7 CM2250 and other CM2250 or CM2220 AN engines shown in the associated procedures table. The fault concerns Battery 2 Voltage, PID P444, SPN 444, FMI 16, where voltage supply to the diesel exhaust fluid controller is higher than electrical system voltage and DEF injection is disabled. Component location is OEM-installed, so the document directs technicians to the OEM service manual for the controller location. See the manufacturer at Cummins official website.
Who needs this Cummins Fault 478 manual
Workshop technicians, diesel mechanics, fleet repair teams, and diagnostic tool users need this manual when an amber CHECK ENGINE lamp or MIL is linked to active Fault Code 478. It is useful for checking active codes 442 or 596, inspecting the 53-pin controller connector, measuring controller supply and return voltage, verifying the Electrical System Voltage parameter in INSITE™, checking alternator output, and confirming ECM calibration status.
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