This document is a auxiliary output DTCs troubleshooting guide covering diagnostic trouble code 0040-05 (Auxiliary Output #02 current low, flash code 66). It provides the conditions that generate this fault code, the ECM system response, and the required test procedure for the Eaton Top 2 transmission circuit. The publication applies to 3406E, C-10, and C-12 on-highway truck engines.
Official auxiliary output DTCs troubleshooting document details
| Brand | Caterpillar (CAT) |
| Model coverage | C-12 Truck Engine 9NS00001-UP; also references 3406E and C-10 on-highway engines |
| System / Group | 3406E C10 C12 (8YS, 9NS, 5DS, or 1LW) — Diagnostic Trouble Codes |
| Publication no. | RENR1328-08 |
| Year / Revision | Published 01/10/2008, updated 16/10/2008 |
| Pages | 1 |
| File size | 0.1 MB |
| Format | |
| Language | English |
Document table of contents
- DTC 0040-05 Auxiliary Output #02 Current Low (66) — SMCS 1901-038
- Conditions Which Generate This Code
- System Response — solenoid behavior and Eaton Top 2 mode disable
- Test Step 1: Eaton Top 2 Transmission Circuit — Test
Applicable truck models
This publication targets Caterpillar C-12 truck engines with serial prefix 9NS, as well as 3406E and C-10 on-highway engines in configurations 8YS, 9NS, 5DS, and 1LW. These powertrains are found in Class 8 trucks from multiple OEMs. The document specifically addresses vehicles equipped with the Eaton Top 2 automated transmission system, where the ECM controls auxiliary solenoid outputs for gear selection. For additional Caterpillar engine support resources, visit Caterpillar’s official support page.
Who needs this auxiliary output DTCs troubleshooting manual
Diesel technicians and workshop owners diagnosing a low-current or open-circuit fault on auxiliary output #02 in CAT 3406E, C-10, or C-12 engines need this reference. It is essential when the ECM disables Eaton Top 2 mode and forces manual transmission operation, helping mechanics isolate wiring or solenoid failures quickly.
The full PDF is available in the DiagTechPro manuals library; a free account is required to download.
Related manuals library
Sản phẩm liên quan cho hãng này
Cùng brand theo taxonomy hiện có trong catalog WooCommerce.
CAT Perkins Pack – Premium Power & Performance by Caterpillar
CAT SIS
