Bobcat A8102 (81-02) Fault Code: ACD/RACD Output "B" Error On
Also shown on the panel as 81-02 · Also called ACD Output ‘B’ Error On
ACD/RACD Output "B" Error On · ai-assisted, editor-reviewed · Last updated 2026-07-13
TL;DR
Bobcat fault code A8102, shown on the panel as 81-02, sets when the ACD/RACD controller sees voltage on output "B" wire 5200 to the attachment solenoid while the controller itself has not energized that circuit. The controller shuts off the output B electric supply, the attachment on output B stops working, and the ACD/RACD icon on the right instrument panel blinks.
Medium severity. The attachment on output B loses power until the fault is fixed, which stops work with that attachment, but it does not by itself threaten the machine, engine, or operator safety. Treat it as a stop-and-diagnose issue rather than an emergency shutdown.
What does Bobcat error code A8102 mean?
, Wire 5200 is the output B feed from the ACD (Attachment Control Device) or RACD (Remote Attachment Control Device) controller to the attachment solenoid coil. The controller expects that wire to carry voltage only when it commands the attachment on, by energizing the coil itself.
When the controller sees voltage on wire 5200 without having sent that voltage, it assumes something else is feeding power into the circuit that should not be there. To protect the system it shuts off the output B driver, so the attachment on that output stops responding, and it lights the blinking ACD/RACD icon on the right instrument panel to alert the operator.
Common causes of A8102
- Circuit output "B" wire 5200 to the attachment solenoid is shorted to a power source
- Fault in the ACD/RACD controller itself
- Moisture, corrosion, or pushed-back pins in the mainframe or attachment control harness connectors
- Loose connections in the wire harness
- An intermittent combination of loose connections, corrosion, pushed-back pins, the controller, and the wire harness, which may not show up if the fault is not active during testing
How to troubleshoot Bobcat A8102: first checks
- Confirm the code is active with the key switch in run/enter, since that is the condition under which the controller checks for this fault
- Inspect the output B wiring at wire 5200 for chafing or contact with a power source that could be feeding stray voltage into the circuit
- Check mainframe and attachment control harness connectors for moisture, corrosion, or pins that have pushed back out of their housings
- Wiggle-test connectors and wiring while watching for the fault to reappear if it is currently intermittent, since it may not be present at the time of testing
- Inspect the attachment solenoid connector and coil wiring for damage that could allow backfeed into wire 5200
How the code clears
Cycle power (turn the key switch off, then back to run/enter) after the repair is complete. No additional reset procedure is listed for this code.
Affected models and serial ranges
A8102 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 |
Frequently asked questions
What does Bobcat code A8102 mean?
It means the ACD/RACD controller detected voltage on attachment output B (wire 5200) when it had not sent voltage to energize that solenoid. The controller shuts off output B and the attachment on that output stops working until the fault clears.
What is the panel display for A8102?
It shows as 81-02 on the numeric panel, along with a blinking ACD/RACD icon on the right instrument panel.
Will my attachment work with A8102 active?
No. Whatever attachment is wired to output B will not function while this code is active, since the controller shuts that output off as a protective measure.
What usually causes A8102?
The most common causes are a short to power on wire 5200, moisture or corrosion in the mainframe or attachment harness connectors, pushed-back pins, loose connections, or a fault in the ACD/RACD controller itself.
How do I clear A8102 after repair?
Cycle the key switch off and back to run/enter. No other clearing steps are listed for this code.
Why can't the technician find A8102 during testing?
If the fault is intermittent, it may not be active at the time of testing. Probable causes for intermittent faults include loose connections, corrosion, pushed-back pins, the controller, or the wire harness, alone or in combination.
Which Bobcat models can show code A8102?
It applies to the S510, S530, S550, S570, S590, S630, S650, S750, S770, T550, T590, T630, T650, T750, and T770 models, plus the T870.