PACCAR DTC 1604 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 Fuel Filter Restriction Pressure Gauge Inoperative, which pairs this code with DTC1603. The stated symptom is that the gauge is inoperative while all other gauges keep working. This excerpt runs 4 pages and starts at manual page 12-34.
What PACCAR DTC 1604 means
The gauge is fed by an electronic transducer that monitors vacuum pressure and converts it to a proportional voltage. PACCAR DTC 1604 is recorded as a short in the fuel filter restriction sensor circuit, when the voltage at the sensor input rises above 4.9 volts. That can be the sensor itself, its ground, or the wiring back to the ICU/CECU.
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 read the on-screen gauge graphic
- Step 3 – “Simulate” test plus CVSG data link daisy-chain continuity checks
- Step 4 – “Diagnose” to confirm which of the two codes is active
- Step 5 – ground, input voltage and output voltage checks at the sensor connector
Wiring and pin references
The sensor connector carries three wires: Pin A is ground, Pin B is the +5 volt input from the ICU/CECU and Pin C is the signal output, which must sit between the two threshold voltages. Ground continuity is proved back to Pin 2 of the 52 pin ICU/CECU connector C, and on the gauge side the daisy chain is checked from Pin 1 to Pin 14 and from Pin 3 to Pin 15 of the same connector. Harness Interface Diagrams, Connector Identification and the ICU/CECU Pinout pages are referenced throughout.
Who needs this PACCAR DTC 1604 manual
Workshop technicians who have the Electronic Service Analyst connected, a digital multimeter in hand, and need the exact pin targets before they start back-probing. Confirm coverage against the official PACCAR corporate site before ordering parts.
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