This PACCAR brake saver oil temperature gauge diagnostic guide addresses DTC 138703 and DTC 138704 faults affecting Cab systems in 2011 and newer PACCAR trucks. Published by PACCAR as part of their Electrical System Service Manual, the document provides systematic troubleshooting procedures for inoperative brake saver oil temperature gauges when all other gauges function normally. The guide assumes technicians are familiar with the Electronic Service Analyst (ESA) hardware and software diagnostic tool.
The brake saver oil temperature gauge uses a thermistor sensor to measure engine retarder oil temperature. When this gauge becomes inoperative, DTC 138703 indicates an open circuit in the brake saver oil temperature sensor circuit, while DTC 138704 signals a short circuit condition. Technicians use this manual to systematically isolate faults to the gauge itself, the CVSG data link wiring, the sensor, or the ICU control module.
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 | 4 |
| File size | 0.1 MB |
| Format | |
| Language | English |
Table of contents
- Brake Saver Oil Temperature Gauge Inoperative — Overview
- Symptom and sensor description
- Step-by-step diagnostic procedure using ESA Monitor and Simulate functions
- DTC 138703 (Open circuit) and DTC 138704 (Short circuit) diagnosis
- Sensor connector continuity checks (Pin A ground, Pin B signal)
- CECU pinout reference and wiring verification
- Thermistor resistance table (-40°F to 392°F with corresponding ohm values)
- Alternate test methods using resistor decade box simulation
- Gauge replacement and ICU replacement procedures
- Final verification and service return steps
Applies to
This brake saver oil temperature gauge manual applies to all 2011 and newer PACCAR trucks equipped with multiplexed instrumentation and engine retarder oil temperature monitoring. The diagnostic procedures cover PACCAR cab electrical systems using the 52-pin ICU (Instrument Control Unit) and CVSG data link configuration. For additional PACCAR service information, visit PACCAR official website.
Who needs this brake saver oil temperature gauge manual
Diesel mechanics and workshop owners diagnosing inoperative PACCAR brake saver oil temperature gauge faults need this manual. Technicians performing electrical system repairs on PACCAR trucks must use this brake saver oil temperature gauge troubleshooting guide to differentiate between sensor failures, wiring faults, and ICU control module defects when DTC 138703 or DTC 138704 appears.
The complete PACCAR brake saver oil temperature gauge diagnostic manual is available in the DiagTechPro manuals library. Register a free account to download the PDF and access all documentation for your workshop’s PACCAR truck repairs.
