Low Battery Voltage Supply is Eaton Fault Code 33, set when the voltage reaching the TECU falls below 7 volts for more than one second on a Fuller Advantage Heavy Duty transmission. This two-page section of publication TRTS0980 defines the J1939 SPN 168 FMI 4 condition, contrasts it with the weaker Fault Code 34 trip below 9 volts, and lists the symptoms and wiring causes. It is the definition page that precedes the Fault Code 33 troubleshooting steps.
Official document details
| Brand | Eaton |
|---|---|
| Model coverage | Fuller Advantage & Fuller Advantage Heavy Duty automated transmission |
| System / Group | DTCs – Fault Isolation Procedures |
| Publication no. | TRTS0980 |
| Year / Revision | 2016 (Rev. 2016.06.20) |
| Pages | 2 |
| File size | 0.4 MB |
| Format | |
| Language | English |
Low Battery Voltage Supply table of contents
- Overview and fault description
- Detection method
- Conditions to set the fault code active
- Fallback and dashboard symptoms
- Conditions to set the fault code inactive
- Possible causes
- Component identification
Applicable truck models covered
This definition covers Eaton Fuller Advantage Heavy Duty automated transmissions on any chassis OEM. Because the fault reflects the vehicle power circuit, it involves the batteries, the charging system, the in-line fuse and the 38-Way Vehicle Harness Connector, all of which follow OEM wiring. Reference transmission data is published on the manufacturer’s official Eaton transmissions website.
Who needs this Battery Voltage Supply manual
Technicians diagnosing a truck that will not crank or will not shift, or one where the driver must shut down in gear, use this page to understand the under-voltage trip and the charging-system and harness causes before load testing. The document also reminds technicians that a single second under seven volts is enough to trip it, so an intermittent connection or a marginal battery bank is a common real-world cause.
The complete PDF, published under Eaton document TRTS0980, is available in the DiagTechPro manuals library; a free account is required to download it.
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