This Cummins 2377 Fan Control document is a fault-code troubleshooting manual for the fan control circuit on Cummins CM2250 engines. It explains Fault Code 2377, where the ECM detects voltage above normal or a short to a high source on the fan control circuit, and it lists the expected effect: the fan can stay on continuously or not run at all.
Official Cummins 2377 Fan Control document details
| Brand | Cummins |
| Model coverage | ISB6.7 CM2250, with associated coverage also shown for ISX11.9 CM2250, ISC8.3 and ISL9 CM2250, ISX15 CM2250, QSL9 CM2250, QSB6.7 CM2250, and other listed Cummins engines |
| System/Group | ISB6.7 CM2250 (2010-12) / DTCs; Fan Control Circuit |
| Publication no. | 4022254 for ISB6.7 CM2250 in the associated procedures table |
| Year/Revision | Last modified 11-Jun-2010; troubleshooting step section last modified 29-Dec-2010 |
| Pages | 15 |
| File size | 0.3 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 fan control solenoid and circuit.
- Guided Step 3 – Check the OEM harness.
- Guided Step 4B – Disable the fault code.
Applicable truck models
The extract identifies this procedure for ISX11.9 CM2250, ISB6.7 CM2250, ISC8.3 and ISL9 CM2250, and ISX15 CM2250 fan control circuits, with the file information placing it in the ISB6.7 CM2250 DTC group. The associated procedures table also lists related Cummins engine models including QSB6.7 CM2250, QSL9 CM2250, GX CM2250, ISB4.5, ISD4.5, ISD6.7 CM2150, ISM11 CM876, ISZ13 CM2150, ISF2.8 CM2220, and ISF3.8 CM2220. For official engine information, visit Cummins official website.
Who needs this Cummins 2377 Fan Control manual
This manual is useful for diesel technicians, fleet workshops, and truck repair shops diagnosing an amber CHECK ENGINE lamp linked to SPN 647 FMI 3/3. It is especially relevant when testing a fan control solenoid, OEM harness, ECM connector pins, PWM signal behavior, and INSITE™ fault status.
The procedure describes checks for inactive fault codes, dirty or damaged connector pins, open circuits in the fan control solenoid, diagnostic supply voltage, return circuit continuity, signal circuit opens, and pin-to-pin shorts in the OEM harness. It also references Cummins procedures for ECM work, ECM calibration code checks, resistance measurement, harness repair, and general connector inspection. The full PDF is available in the DiagTechPro manuals library, free account required to download.
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