Bobcat A8505 (85-05) Fault Code: ACD/RACD Output “F” Short to Battery
Also shown on the panel as 85-05 · Also called ACD Output ‘F’ Short to Battery, ACD/RACD Output “F” Short to Battery
ACD/RACD Output “F” Short to Battery · ai-assisted, editor-reviewed · Last updated 2026-07-13
TL;DR
A8505 (panel form 85-05) sets when the ACD/RACD controller sees voltage on Output "F" (controller pin J1 B-19) when the controller has not commanded it. The controller disables Output "F" as a protective response. It is set with the key switch or run/enter switch on.
Medium severity. Output "F" is disabled once the code sets, which can shut down whatever attachment function that output controls. It is not an engine or structural safety event, but it should be diagnosed before relying on that attachment output again.
What does Bobcat error code A8505 mean?
A8505 belongs to Bobcat's Attachment Control Device / Remote Attachment Control Device (ACD/RACD) system, which manages powered attachment outputs on compatible loaders and excavators. Output "F" is one of the controller's solenoid driver circuits, and the controller expects that circuit to only carry voltage when it has commanded it on.
When the controller instead detects voltage on Output "F", at controller pin J1 B-19, without having commanded it, it assumes a wiring or component fault is feeding unwanted voltage into that circuit. To protect the solenoid, wiring, and controller, it disables Output "F" until the fault is cleared.
This means whatever attachment function depends on Output "F" will stop working as soon as the code sets, so operators may notice a specific attachment function go dead even though the rest of the machine runs normally.
Common causes of A8505
- Output "F" wiring at controller pin J1 B-19 shorted to battery voltage
- Return wire at controller pin J1 A-18 shorted to battery voltage
- A failed Output "F" solenoid
- A fault inside the ACD/RACD controller itself
- Moisture, corrosion, or pushed-back pins in the ACD/RACD controller connectors, mainframe harness, attachment control harness, or the Output "F" solenoid connector
- Intermittent conditions from loose connections, corrosion, pushed-back pins, the controller, the wire harness, or a combination of these, which may not be found if the fault is not active during testing
How to troubleshoot Bobcat A8505: first checks
- Confirm the code is active with the key switch or run/enter switch on, since this is the condition under which A8505 sets
- Inspect the ACD/RACD controller connectors, mainframe harness connectors, attachment control harness connectors, and the Output "F" solenoid connector for moisture, corrosion, or pushed-back pins
- Check the wiring at controller pin J1 B-19 (Output "F") for a short to battery voltage
- Check the return wire at controller pin J1 A-18 for a short to battery voltage
- Test the Output "F" solenoid itself for an internal fault that could feed battery voltage back into the circuit
- If the code will not stay active for testing, treat it as intermittent and inspect all connections, harness routing, and pins for looseness or damage before suspecting the controller
How the code clears
Cycle power to clear the code once the repair is complete. No separate clearing step is listed beyond cycling power.
Affected models and serial ranges
A8505 appears in our records across 20 Bobcat models. Match your machine by model and serial number.
| Model | Serial ranges |
|---|---|
| E35 | SN A93K110001-99999, SN AC2P11001-99999 |
| E42 | SN AG3411001-99999 |
| E45 | SN AG3G11001-99999, SN AHHC11001-99999 |
| E55 | SN ARWM11001-99999, SN ASW311001-99999 |
| 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 A3NT10001-12369, 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 |
Frequently asked questions
What does Bobcat code A8505 mean?
It means the ACD/RACD controller detected voltage on Output "F" (controller pin J1 B-19) when it had not commanded that output on, so it disabled Output "F" to protect the circuit.
What is the panel display form of A8505?
On the machine display it may appear in numeric panel form as 85-05.
Will my attachment stop working with this code?
Yes, the controller disables Output "F" once A8505 sets, so any attachment function wired to that output will stop functioning until the fault is fixed and the code is cleared.
What usually causes A8505?
Common causes include a short to battery voltage on the Output "F" wire or its return wire, a failed Output "F" solenoid, a fault in the ACD/RACD controller, or moisture, corrosion, or pushed-back pins in the related connectors and harnesses.
How do I clear A8505 after repair?
Cycle power to the machine. That is the only clearing step listed for this code.
Why can't the technician find the cause of my A8505 code?
If the code is intermittent and not active at the time of testing, the exact cause may not be found right away. Likely culprits in that case are loose connections, corrosion, pushed-back pins, the controller, or the wire harness, sometimes in combination.
Which Bobcat machines can show code A8505?
It applies to models including the E35, E42, E45, E55, S510, S530, S550, S570, S590, S630, S650, S750, S770, T550, T590, T630, T650, T750, and T770, among others equipped with the ACD/RACD system.