PACCAR DTC 138704 is documented in Chapter 12 of the PACCAR Electrical System Service Manual, publication PM819010/KM815054, revised 04/01/2010. It is the short-circuit half of the section titled Brake Saver Oil Temperature Gauge Inoperative, which pairs this code with DTC138703. The stated symptom is that this gauge is inoperative while the others keep working. This excerpt runs 4 pages and starts at manual page 12-77.
What PACCAR DTC 138704 means
The reading comes from a thermistor sensor that measures engine retarder oil temperature. PACCAR DTC 138704 is displayed as a short in the brake saver oil temp circuit, which the manual says can be a short to ground in the wiring from the ICU/CECU to the sensor, or a defective sensor. The procedure separates those two cases instead of guessing.
Document details and coverage
| Brand | PACCAR |
|---|---|
| Model coverage | PACCAR cab instrumentation with ICU/CECU, 2005-2010 |
| System / group | Chapter 12 Electrical System – DTCs, Cab (2005-2010) |
| Publication no. | PM819010/KM815054 |
| Revision | 04/01/2010 |
| Pages | 4 |
| File size | 0.2 MB |
| Format / language | PDF, English |
Procedure sections in this excerpt
- Symptom statement and sensor theory of operation
- Step 1 – start ESA and select “Connect” with the ignition key ON
- Step 2 – “Monitor” the component and judge the on-screen reading
- Step 3 – “Simulate” test and CVSG data link daisy-chain checks
- Step 4 – “Diagnose” to see which of the two codes is active
- Steps 5 to 7 – continuity checks, a thermistor resistance table and jumper-wire confirmation
Wiring and pin references
At the sensor connector, Pin A is ground and must show continuity to a cab ground terminal, while Pin B is the signal wire and must show continuity to Pin 24 of the 52 pin ICU/CECU connector C. On the gauge side the manual checks Pin 1 to Pin 14 and Pin 3 to Pin 15 of the same connector to clear the CVSG daisy chain. The jumper test is the decisive check: bridging the two sensor pins should flip the fault to the opposite code, which proves the wiring is intact and the sensor is the failed part. A temperature versus resistance table is printed for bench-checking the thermistor.
Who needs this PACCAR DTC 138704 manual
Truck technicians and workshop owners who want the pin targets and the resistance table in front of them before they condemn a sensor or a harness. Confirm coverage against the official PACCAR corporate site before ordering parts.
The full PDF is free to read in the DiagTechPro manuals library, where an account is needed to download it.
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