This document is the 2013 PACCAR MX Diagnostic Service Manual covering MX engine fault code P0691, which addresses electronic controlled fan voltage faults and short circuits. Published by PACCAR for their MX diesel engine lineup, this manual provides technicians and workshop owners with the technical framework needed to diagnose and resolve ECU pin D420 voltage anomalies on EPA 2013-compliant truck engines.
Document details and specifications — MX engine fault
| Brand | PACCAR |
| Model coverage | PACCAR MX Engines |
| System/Group | DTCs / MX Engines (EPA 2013) |
| Publication number | Not specified |
| Year/Revision | 2013 |
| Pages | 1 |
| File size | 0.3 MB |
| Format | |
| Language | English |
Table of contents
- Code number P0691
- Fault code description
- Fault code information and readiness group
- Description of component(s)
- Location of component(s)
- Diagnostic condition
- Set condition of fault code
- Reset condition of fault code
- Electrical diagram(s)
- Technical data
- Possible causes
- Additional information
- Diagnostic Step-by-Step procedures
- Verification and drive cycle information
Applies to these models
This MX engine fault code P0691 manual applies to PACCAR MX diesel engines manufactured to EPA 2013 emissions standards. The fault code specifically relates to the electronic controlled fan circuit on ECU pin D420, affecting cooling system diagnostics across the MX engine family used in commercial trucks. For complete engine and vehicle specifications, visit PACCAR official.
Who needs this engine fault code P0691 manual
Diesel mechanics, heavy-duty truck technicians, and workshop owners diagnosing electronic controlled fan voltage faults will find this engine fault code P0691 reference essential. The manual supports shops performing comprehensive electrical diagnostics on EPA 2013-compliant PACCAR powertrains.
The complete engine fault code P0691 diagnostic manual is available in the DiagTechPro manuals library. Create a free account to download this essential reference document for your workshop.
Related manuals library
Using this document effectively
Use MX engine fault code P0691 — Electronic Controlled Fan Voltage 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.
