CAT Engine 27704 Fault Code: Throttle Lock Resume/Decel Switch : Voltage Below Normal
Throttle Lock Resume/Decel Switch : Voltage Below Normal · ai-assisted, editor-reviewed · Last updated 2026-07-13
TL;DR
CAT fault code 27704 sets when both contacts of the throttle lock resume/decel switch are seen closed at the same time. The ECM logs the code and disables the throttle hold and throttle lock features until the fault is resolved.
Medium severity. This code does not stall the engine or create an immediate safety hazard by itself, but it disables throttle lock and throttle hold, which changes how the operator controls engine speed. Operators used to relying on throttle lock for steady rpm during PTO work or repetitive cycles should be aware the feature is unavailable until the fault clears.
What does CAT Engine error code 27704 mean?
Code 27704 points to the throttle lock resume/decel switch, part of the throttle lock system that lets an operator set and hold a desired engine speed instead of using the throttle pedal continuously. This switch, mounted on the joystick, is used to decrease the locked engine speed (RESUME/DECEL function).
The ECM expects this switch to behave like a normal two-position momentary switch: either open or closed, not both at once. When the ECM sees both contacts closed at the same time, it treats that as an invalid or shorted signal and sets code 27704.
Once logged, the ECM disables both the throttle hold feature and the throttle lock feature entirely. This means the operator loses automatic and manual throttle lock modes and must control engine speed manually through the throttle pedal until the issue is fixed.
What triggers a CAT Engine 27704 code?
The code sets when the ECM detects both contacts of the throttle lock resume/decel switch in the closed state at the same time.
Common causes of 27704
- Harness or wiring abrasion, corrosion, or pinch points affecting the switch circuit
- Fault in the circuit for the throttle lock switch
- Fault in the throttle lock switch itself
- Problem in the circuit between the ECM and the throttle lock switch
- Faulty ECM needing replacement
- Open or short circuit in the wiring between the ECM and the switch
- Problem in the circuit for the throttle lock resume/decel switch specifically
- Throttle lock resume/decel switch needing replacement
- Problem in the circuit between the ECM and the throttle lock resume/decel switch
- Faulty ECM
How to troubleshoot CAT Engine 27704: first checks
- Inspect the wiring harness running to the throttle lock resume/decel switch on the joystick for abrasion, corrosion, or pinch points, especially where it flexes near the joystick base
- Check all connectors in the circuit between the ECM and the throttle lock resume/decel switch for corrosion, loose pins, or moisture intrusion
- Test the throttle lock resume/decel switch itself for a stuck or shorted contact that could cause both sides to read closed simultaneously
- Verify the throttle lock switch (the three-position rocker used to select Automatic, Manual, or OFF mode) is functioning correctly, since its circuit is also listed among possible causes
- Trace the full circuit path between the ECM and both switches for any open or short conditions before condemning the ECM
How the code clears
No separate clearing step is listed. Once the wiring, switch, or connector fault causing both contacts to read closed is repaired, the ECM should stop logging the code on the next key cycle or operating condition where it re-evaluates the switch state. If the fault persists after wiring and switch checks come back clean, ECM replacement is listed as a possible cause.
Frequently asked questions
What does CAT code 27704 mean?
It means the ECM detected both contacts of the throttle lock resume/decel switch closed at the same time, which is not a valid switch state. The ECM logs the code and turns off the throttle hold and throttle lock features.
Can I still drive or operate the machine with code 27704 active?
Yes. The throttle pedal remains the primary means of controlling engine speed. You simply lose the ability to use throttle lock or throttle hold to maintain a set engine speed automatically until the fault is repaired.
Will code 27704 cause the engine to stall or derate?
Nothing in the diagnostic information for this code describes a stall or derate response. The listed system response is limited to disabling the throttle hold and throttle lock features.
What is the difference between the throttle lock switch and the throttle lock resume/decel switch?
The throttle lock switch is a three-position rocker used to select Automatic, Manual, or OFF mode. The throttle lock resume/decel switch is a separate two-position momentary switch on the joystick used to decrease the locked engine speed. Code 27704 is specific to the resume/decel switch.
How do I fix code 27704?
Start by inspecting the harness and connectors between the ECM and the throttle lock resume/decel switch for damage, corrosion, or pinch points. Test the switch itself for a stuck or shorted contact. If wiring and switch both check out, the circuit between the ECM and the throttle lock switch should also be checked, since it is listed as a related cause. ECM replacement is only indicated if everything else tests good.
Is there a reset procedure for code 27704?
No reset procedure is listed for this code. Repairing the underlying wiring or switch fault should allow the ECM to clear the fault on its own once it no longer detects both contacts closed.