This PACCAR MX EPA diesel P1054A diagnostic manual covers the downhill speed control switch fault code for MX-series truck engines. Published by PACCAR and extracted from the Rapido technical portal, this 2-page reference explains the set conditions, diagnostic procedures, and repair verification steps for P1054A on EPA 2004 and EPA 2013 compliant powerplants.
The PACCAR MX EPA diesel P1054A occurs when the PCI ECU (D420) detects simultaneous activation of both the downhill speed control activation and deactivation switches—a mechanical or electrical conflict that prevents proper system function.
Document details and specifications — PACCAR MX EPA
| Brand | PACCAR |
| Model coverage | MX-11 E6, MX-13 E6, MX EPA13, MX EPA04 |
| System/Group | DTCs / MX Europe Engines (EPA 2004) |
| Publication number | M033228 |
| Year/Revision | 08.20.2016 |
| Pages | 2 |
| File size | 0.1 MB |
| Format | |
| Language | English |
Table of contents
- Set conditions for P1054A activation
- Diagnostic condition overview
- OBD readiness monitor status
- Reset condition parameters
- Repair verification procedure
- Possible cause analysis
- Additional information on downhill speed control function
Applies to these models
This MX EPA diesel P1054A reference applies to MX-11 E6 and MX-13 E6 chassis engines, as well as MX EPA13 and MX EPA04 powerplants certified under EPA emissions standards. For official technical support and additional bulletins, visit PACCAR official site.
Who needs this MX EPA diesel P1054A manual
Heavy-duty diesel technicians and shop owners servicing PACCAR MX-series trucks need this P1054A diagnostic guide to identify and repair downhill speed control switch failures. The manual is essential for mechanics diagnosing continuous activation faults in EPA-compliant engines.
The complete MX EPA diesel P1054A PDF is available in the DiagTechPro manuals library. Free account registration is required to download this and thousands of other OEM diagnostic references.
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Using this document effectively
Use PACCAR MX EPA diesel P1054A — Downhill Speed Control Switch as a reference alongside the exact machine identification, engine family, control module, and publication revision shown on the equipment. Confirm that the model and production range match before following any table, connector view, test sequence, or specification. Record the original fault code and operating conditions before clearing codes or disconnecting components.
