Bobcat W3251 (32-51) Fault Code: ACS Lift Actuator Short to Battery (Error On) (ACS Only)
Also shown on the panel as 32-51 · Also called ACS (AHC) Lift Actuator Short to Battery, ACS Lift Actuator Short to Battery (Error On) (SJC Only)
ACS Lift Actuator Short to Battery (Error On) (ACS Only) · ai-assisted, editor-reviewed · Last updated 2026-07-21
TL;DR
W3251 (panel code 32-51) sets when the ACS controller sees the lift actuator signal wire voltage rise above 4.9 volts, above the controller's own 5.0 volt sensor supply. Lift and tilt functions are disabled until the fault is fixed and power is cycled.
High severity. The machine disables both lift and tilt functions the moment this code sets, which takes away loader control until the fault clears. It is not an engine-damage emergency, but it stops productive work and should be diagnosed before returning to the job.
What does Bobcat error code W3251 mean?
W3251 is set by the Advanced Control System (ACS) controller when it reads the lift actuator's position signal wire at a voltage greater than 4.9 volts. The controller normally feeds this sensor circuit with a 5.0 volt supply, so a signal reading pinned near or at that supply level tells the controller the signal has been pulled up too high rather than following the actuator's actual position.
This is a classic signal-high fault: something is feeding extra voltage onto the signal circuit, or the ground path the sensor depends on to produce a valid low-to-mid range signal has been lost. Either way, the controller cannot trust the position feedback from the lift actuator, so it shuts down lift and tilt to prevent uncontrolled movement.
Depending on the exact model and harness build, the affected signal wire is numbered 4670 or 3980, and the related 5 volt supply and ground wires vary by harness (1610/5980, 1530/5870, and grounds 2630, 2670, or 2980). The failure logic is the same across all these variants.
What triggers a Bobcat W3251 code?
The ACS controller sets W3251 when the lift actuator's signal wire voltage exceeds 4.9 volts while the key switch or run/enter switch is on. The controller supplies 5.0 volts to the lift actuator sensor circuit as its reference.
Common causes of W3251
- The lift actuator needs calibrating, which can cause the controller to see out-of-range signal voltage even without a wiring fault.
- The 5 volt supply wire to the lift actuator sensor (1610, 5980, or 1530 depending on harness) is shorted to supply (battery) voltage, pushing extra voltage onto the sensor circuit.
- The signal wire itself (4670 or 3980) is shorted to supply voltage, most often from chafed insulation contacting a powered wire in the harness.
- The ground wire for the lift actuator sensor (2630, 2670, or 2980) is open, which removes the sensor's reference ground and lets the signal float high.
- A failed lift actuator (internal sensor fault) is sending an invalid high signal on its own.
- A failed ACS controller.
- Moisture, corrosion, or pushed-back pins in the ACS controller connectors, the lift actuator connector, or the ACS harness connectors.
- If the code is intermittent and not active at the time of testing, the cause may not be found immediately. Likely culprits in that case are loose connections, corrosion, pushed-back pins, the controller, the harness, or a combination of these.
How to troubleshoot Bobcat W3251: first checks
- With the key on and the code active, check the lift actuator signal wire voltage at the controller and at the actuator connector; a reading pinned above 4.9 volts confirms the high-signal fault is currently present.
- Inspect the ACS controller connectors, the lift actuator connector, and the harness in between for moisture, corrosion, or pins that have been pushed back out of their sockets.
- Check the 5 volt supply wire to the lift actuator sensor for a short to battery voltage; disconnect the sensor and see if supply voltage stays out of range, which points to a harness short rather than a bad sensor.
- Verify the ground wire for the lift actuator sensor has continuity back to the controller ground; an open ground will let the signal float high even with a good sensor.
- Inspect the harness routing for chafe points where the signal wire could be rubbing against a wire carrying full supply voltage.
- Run or check the lift actuator calibration procedure, since an uncalibrated actuator can trigger this code even with sound wiring.
- If the fault will not reproduce, wiggle-test the harness and connectors while watching for the code to set, since an intermittent short or pushed-back pin may only show up under vibration or movement.
How the code clears
Once the wiring, connector, actuator, or controller issue is repaired, cycle the key power off and back on. No separate clearing procedure beyond a power cycle is listed for this code.
Affected models and serial ranges
W3251 appears in our records across 16 Bobcat models. Match your machine by model and serial number.
| Model | Serial ranges |
|---|---|
| S510 | SN A3NJ11001-99999, SN A3NK11001-99999, SN ATZC11001-99999 |
| S530 | SN A7TV11001-99999, SN ATZD11001-99999 |
| S550 | SN A3NK11001-A3NL99999, SN A3NM11001-99999 |
| S570 | SN A7U711001-799999, SN A7U811001-899999 |
| S590 | SN ANMN11001-99999, SN ANMP11001-99999 |
| S630 | SN A3NT12370-99999, SN A3NU11001-11111, SN A3NU11112-99999 |
| S650 | SN A3NV11001-13098, SN A3NV13099-99999, SN A3NW11001-11248, SN A3NW11249-99999 |
| S750 | SN A3P211001-299999 |
| S770 | SN A39511001-99999, SN A3P411001-99999 |
| T550 | SN A7UJ11001-AJZV12276 |
| T590 | SN ALJU11001-999999, SN B37811001-999999, SN B3Z711001-999999 |
| T630 | SN A7PU11001-11663, SN A7PU11664-99999 |
| T650 | SN A3P012214-099999, SN A3P111242-199999 |
| T750 | SN ANKA11001-A99999 |
| T770 | SN A3P811001-899999, SN A3P911001-999999 |
| T870 | SN A3PG11001-99999, SN A3PH11001-99999 |
Frequently asked questions
What does Bobcat fault code W3251 mean?
It means the ACS controller detected the lift actuator's signal wire voltage above 4.9 volts, higher than the normal 5.0 volt reference range the controller expects to see valid position data on. The controller disables lift and tilt as a safety response.
Can I keep operating the machine with W3251 active?
No, not normally, because lift and tilt functions are disabled automatically once the code sets. You will need to diagnose and repair the fault before those functions return.
Does W3251 always mean the lift actuator itself is bad?
Not necessarily. A shorted 5 volt supply wire, a signal wire shorted to battery voltage, or an open ground wire can all produce the same high-signal reading even when the actuator itself is fine. Check the wiring and connectors before replacing the actuator.
Will calibrating the lift actuator fix this code?
It might. An uncalibrated lift actuator is listed as a possible cause, so running the calibration procedure is a reasonable early step, especially if wiring and connectors check out fine.
How do I clear W3251 after making a repair?
Cycle the key power off and back on. No additional reset steps are listed beyond that power cycle.
What is the difference between W3251 and W3252?
W3251 covers the lift actuator's signal circuit reading a short to battery (signal too high), while W3252 covers the same short-to-battery fault mode on the tilt actuator circuit instead of the lift circuit. If your symptom involves tilt function loss with a high-signal reading, check W3252 instead.
Why does an open ground wire cause a high voltage reading instead of a low one?
When the sensor's ground reference is lost, the signal wire is no longer pulled down by the sensor's internal circuit and can float up toward the 5 volt supply level, which the controller reads as an out-of-range high signal even though there is no actual short to battery voltage.