CAT 00 Fault Code: Brake Pedal Switch #2 Fault
Brake Pedal Switch #2 Fault · ai-assisted, editor-reviewed · Last updated 2026-07-13
TL;DR
CAT code 00, SPN 603 FMI 11, means the ECM has detected that Service Brake Pedal Position Switch 2 disagrees with Switch 1 for at least 15 seconds while the engine is running. This applies to C11, C13, and C15 engines and points to a redundant brake pedal switch or wiring problem.
Medium severity. This is a redundancy-check fault, not a loss of braking itself, but it disables functions tied to the brake switches (cruise control exit, PTO mode exit, idle shutdown override) and should be diagnosed before relying on those features.
What does CAT error code 00 mean?
This fault means the ECM found that the two service brake pedal position switches disagree with each other. Switch 1 and Switch 2 are supposed to report the same brake pedal status at all times. Switch 2 exists purely for redundancy, and unlike Switch 1 it connects to positive battery voltage instead of ground, so the two switches can be cross-checked electrically as well as logically.
These brake pedal switches do more than just signal braking. They are used to exit cruise control, exit Cab Switch PTO mode, exit idle, and override the idle shutdown timer during its final 90 seconds. When the switches disagree, the ECM cannot trust the brake pedal status, so it logs this fault to flag the mismatch.
The code sets when the engine is running, the ECM has been powered for at least 3 seconds, and the two switch statuses do not match for 15 seconds or more.
What triggers a CAT 00 code?
The ECM sets this code when the status of Service Brake Pedal Position Switch 2 does not match the status of Service Brake Pedal Position Switch 1 for at least 15 seconds, while the engine is running and the ECM has been powered for at least 3 seconds.
Common causes of 00
- The ECM is programmed improperly for the brake pedal switch configuration
- A poor or corroded connection at the ECM connector, or damage in the ECM harness
- A failed or misadjusted Service Brake Pedal Switch (Switch 2)
- Damage, an open circuit, or a short in the Service Brake Pedal Switch harness
How to troubleshoot CAT 00: first checks
- Confirm the engine was running and had been powered for at least 3 seconds when the fault logged, to rule out a transient power-up mismatch
- Inspect the ECM connector and harness for corrosion, loose pins, or chafed wiring near the brake pedal switch circuits
- Check the Service Brake Pedal Switch #2 for proper mechanical operation and correct adjustment under the pedal
- Verify the Switch 2 circuit is wired to positive battery voltage as designed, since it is intentionally wired opposite to Switch 1 for redundancy
- Compare the live status of both brake pedal switches with a scan tool while pressing and releasing the pedal to see if they agree
- Check ECM programming or configuration to confirm the redundant brake switch setup matches the machine's actual wiring
How the code clears
No separate clearing step is listed for this code. Repair the wiring, connector, or switch fault, confirm both brake pedal switches agree in status, and the ECM should stop logging the fault on its own once the mismatch is resolved.
Affected models and serial ranges
00 appears in our records across 3 CAT models. Match your machine by model and serial number.
| Model | Serial ranges |
|---|---|
| C11 | Serial range not listed in source records |
| C13 | Serial range not listed in source records |
| C15 | Serial range not listed in source records |
Frequently asked questions
What does CAT fault code 00 SPN 603 FMI 11 mean?
It means the ECM detected that Service Brake Pedal Position Switch 2 does not agree with Switch 1 for at least 15 seconds while the engine is running. It is a redundancy mismatch fault on C11, C13, and C15 engines.
Is it safe to keep driving with this fault active?
The engine will still run and the brakes still physically work, but functions that rely on the brake switches, such as exiting cruise control, exiting PTO mode, or overriding the idle shutdown timer in its last 90 seconds, may not behave correctly. Get it diagnosed rather than ignoring it.
Why does the truck have two brake pedal switches?
Switch 2 provides a fully redundant system. It performs the identical function as Switch 1 but connects to positive battery voltage instead, so the ECM can cross-check that both switches report the same brake pedal status.
What usually causes this fault?
Improper ECM programming for the brake switch setup, a bad ECM connector or harness, a failed Service Brake Pedal Switch, or damage in the switch harness are the listed probable causes.
How do I clear code 00 after repairs?
No separate clearing step is listed. Once the wiring, connector, or switch issue is fixed and both brake pedal switches agree in status, the fault should stop being active.
Does this fault affect cruise control or PTO operation?
Yes. The brake pedal switches are used to exit cruise control and Cab Switch PTO mode, and to exit idle. A mismatch between the switches can interfere with these functions working as expected.