This PACCAR dash dimmer input diagnostic manual covers troubleshooting procedures for inoperative dash dimmer circuits on 2011 and newer PACCAR trucks. Published by PACCAR and titled Electrical System Service Manual, it provides step-by-step diagnosis using the Electronic Service Analyst (ESA) diagnostic tool to identify open, shorted, or faulty dimmer control inputs and outputs.
The document addresses four related diagnostic trouble codes: DTC 148703 (open dash dimmer input), DTC 148704 (shorted dash dimmer input), DTC 149106 (shorted output circuit 1), and DTC 149206 (shorted output circuit 2).
Document details
| Brand | PACCAR |
| Model coverage | 2011 and newer PACCAR trucks |
| System/Group | DTCs / Cab Electrical System |
| Publication number | PM819003/KM815056 |
| Year/Revision | 09/16/2011 |
| Pages | 2 |
| File size | 0.1 MB |
| Format | |
| Language | English |
Table of contents
- Symptom: Dash dimmer inoperative
- Overview of dash dimmer input signal from driver-controlled rheostat
- Step-by-step troubleshooting procedure using ESA hardware/software
- Diagnosis of DTC 148703 – Open in dash dimmer input circuit
- Diagnosis of DTC 148704 – Short in dash dimmer input circuit
- Dimmer switch resistance testing (390–1390 ohms range)
- CECU connector pin identification and continuity checks
- Diagnosis of DTC 149106 – Short in dash dimmer output circuit 1
- Diagnosis of DTC 149206 – Short in dash dimmer output circuit 2
- Electrical connection inspection and component replacement guidance
Applies to
This manual applies to all PACCAR trucks manufactured in 2011 and newer model years equipped with multiplexed instrumentation and CECU (Cabin Electronic Control Unit) systems. The dash dimmer input circuit connects the driver-controlled dimmer rheostat to the CECU through Pin 5 of the 52-pin connector C, while dimmer outputs route through Pin 7 and Pin 8 of the 9-pin connector A to control cab backlighting brightness. For official PACCAR service documentation and truck specifications, visit PACCAR official.
Who needs this PACCAR dash dimmer input manual
Diesel mechanics, electrical technicians, and workshop owners diagnosing PACCAR cab electrical faults need this dash dimmer input troubleshooting guide. Technicians proficient with ESA diagnostic software will find this manual essential for isolating open circuits, ground shorts, and faulty dimmer control switches on 2011+ PACCAR trucks.
The complete PACCAR dash dimmer input diagnostic manual (Code 148703.pdf) is available in the DiagTechPro manuals library. A free account is required to download.
