This Eaton Fault Code 21 procedure is the official Fuller Advantage Heavy Duty fault-isolation document (publication TRTS0980) for diagnosing the Park Brake Switch configuration. The 2-page PDF explains how to determine whether the switch is hard-wired to the TECU or broadcast over the J1939 Data Link, then confirm the configuration and wiring with ServiceRanger.
Eaton Fault Code 21 document details
| Brand | Eaton |
|---|---|
| Model coverage | Fuller Advantage Heavy Duty and Fuller Advantage |
| System / Group | DTCs / Fault Isolation Procedures |
| Publication no. | TRTS0980 |
| Year / Revision | 2016.06.20 (© 2016 Eaton) |
| Pages | 2 |
| File size | 0.1 MB |
| Format | |
| Language | English |
Fault isolation steps included
- Step A — Verify whether a physical Park Brake Switch is installed on the chassis
- Step B — Confirm the hard-wired switch configuration matches the installation
- Step C — Confirm operation of the TECU hard-wired switch (4.0–5.0 V)
- Step D — Determine whether the configuration matches the J1939 brake switch
- Step V — Verify repair with ServiceRanger
Applicable transmissions and switch
The procedure covers Fuller Advantage Heavy Duty transmissions using either a 2-Way hard-wired Park Brake Switch to the TECU or a switch broadcast over the J1939 Data Link. It references the ServiceRanger User Guide (TCMT0072) for configuration. Technicians first inspect the vehicle to determine which switch type is fitted, then record and, if needed, correct the Hard-Wired Park Brake Switch value between Installed and Not Installed. Manufacturer data is published on Eaton’s official Roadranger website.
Who needs this Eaton Fault Code 21 manual
Technicians and workshop owners diagnosing an active fault or a mismatched park-brake configuration use this manual to set the correct ServiceRanger value before replacing any wiring. It also gives the expected 4.0 to 5.0 volt reading across the 2-Way connector so a good switch is not replaced needlessly.
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