CAT Engine 27703 Fault Code: Throttle Lock Resume/Decel Switch Voltage Above Normal
Also called Throttle Lock Resume/Decel Switch : Voltage Above Normal
Throttle Lock Resume/Decel Switch Voltage Above Normal · ai-assisted, editor-reviewed · Last updated 2026-07-13
TL;DR
CAT fault code 27703 sets when the ECM detects that both contacts of the throttle lock resume/decel switch are open at the same time. The ECM logs the code, disables the throttle hold and throttle lock features, and a warning shows on the control panel display.
Medium severity. This code does not stop the engine or create an immediate safety hazard, but it disables automatic engine speed control (throttle hold and throttle lock). Operators relying on those features for repetitive tasks will lose that convenience until the fault is fixed. Diagnose it within the shift rather than ignoring it, especially if the machine is used for stationary or PTO-type work that depends on throttle lock.
What does CAT Engine error code 27703 mean?
Fault code 27703 means the ECM has seen both contacts of the throttle lock resume/decel switch sitting in the open state at the same time. That is not a normal operating condition for the switch, so the ECM flags it as a voltage-above-normal fault and logs a diagnostic code.
When this happens, the ECM disables the automatic control of engine speed through both the throttle hold feature and the throttle lock feature. The operator will only be able to control engine speed with the throttle pedal until the fault clears. A warning appears on the control panel display as well.
The throttle lock feature normally lets an operator set and hold an engine speed using the throttle lock switch (a three-position rocker for Automatic, Manual, or OFF) along with the throttle lock set/accel switch and the throttle lock resume/decel switch on the joystick. With code 27703 active, none of that automatic speed-holding works, since the resume/decel switch input the ECM needs is reporting an open-circuit condition.
Common causes of 27703
- Harness or wiring abrasion, corrosion, or a pinch point in the throttle lock circuit
- Fault in the circuit for the throttle lock switch itself
- Fault in the throttle lock switch
- Problem in the circuit between the ECM and the throttle lock switch
- 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 needs to be replaced
- Problem in the circuit between the ECM and the throttle lock resume/decel switch
- Faulty ECM (needs replacement)
- Faulty or corroded connector and/or wiring (harness problem)
- Intermittent connection problem
How to troubleshoot CAT Engine 27703: first checks
- Inspect the wiring harness and connectors for the throttle lock resume/decel switch for abrasion, corrosion, or pinch points, especially where the harness routes near the joystick or moving parts
- Check all connectors in the circuit between the ECM and the throttle lock switch and the throttle lock resume/decel switch for loose pins, corrosion, or moisture intrusion
- Test the throttle lock resume/decel switch itself for proper operation in both the RESUME and DECEL directions to confirm both contacts function and are not stuck open
- Check for open or short circuits in the wiring between the ECM and the switch using the electronic service tool to view live status while operating the switch
- Wiggle-test the harness while monitoring the switch status on the service tool to catch an intermittent open circuit
- If wiring, connectors, and the switch all check out, consider the ECM itself may be faulty and needs further diagnosis or replacement
How the code clears
No separate clearing step is listed beyond repairing the fault. Once the open circuit condition in both contacts of the throttle lock resume/decel switch is corrected, whether that means repairing wiring, replacing the switch, or repairing/replacing the ECM, the ECM should stop logging the code and throttle hold and throttle lock functions should return to normal operation. Use the electronic service tool to confirm the code is no longer active after repairs.
Frequently asked questions
What does CAT code 27703 mean?
It means the ECM detected that both contacts of the throttle lock resume/decel switch were open at the same time, which is outside normal operating conditions. The ECM logs the fault and disables the throttle hold and throttle lock features.
Will code 27703 stop my machine from running?
No. The engine keeps running and the throttle pedal still controls engine speed normally. What you lose is the automatic throttle hold and throttle lock features, so you have to control engine speed manually with the pedal until the fault is repaired.
Can I still use throttle lock with this code active?
No. When the ECM detects this fault it disables automatic control of engine speed through both the throttle hold feature and the throttle lock feature. The throttle lock switch positions (Automatic, Manual, OFF) will not restore the feature until the underlying wiring or switch problem is fixed.
What usually causes this fault?
Most cases trace back to wiring problems: abrasion, corrosion, or pinched harness near the throttle lock resume/decel switch, or a bad connector. A faulty switch or an intermittent connection is also common. A bad ECM is possible but less common and should be checked only after wiring and the switch are confirmed good.
Is the throttle lock resume/decel switch the same as the throttle lock set/accel switch?
No. The set/accel switch increases desired engine speed (SET/ACCEL), while the resume/decel switch on the joystick decreases desired engine speed (RESUME/DECEL). Code 27703 is specific to the resume/decel switch having both contacts open.
How do I confirm the repair worked?
After repairing the wiring, connector, switch, or ECM as needed, use the electronic service tool to verify the code is no longer active and test that throttle hold and throttle lock features operate normally again in both Automatic and Manual modes.