Bobcat A8602 (86-02) Fault Code: ACD/RACD Output "G" Error On
Also shown on the panel as 86-02 · Also called ACD Output ‘G’ Error On
ACD/RACD Output "G" Error On · ai-assisted, editor-reviewed · Last updated 2026-07-21
TL;DR
A8602 (panel display 86-02) sets when the ACD/RACD controller sees voltage on output "G" wire 5400 while it has not commanded that output on. The controller shuts off the "G" output, the attachment on that circuit stops working, and the ACD/RACD icon on the right instrument panel blinks.
Medium severity. The affected attachment function on output "G" is disabled until the fault is fixed, but this is an attachment control circuit issue, not a core machine safety or drivetrain system, so the machine can typically still be used for other functions while you diagnose it.
What does Bobcat error code A8602 mean?
A8602 is an electrical logic fault on Bobcat's ACD/RACD (attachment control device / remote attachment control device) system. The controller monitors output "G", the wire that sends power to energize an attachment solenoid coil. It expects to see voltage on that wire only when it has actively switched it on.
When the controller detects voltage on wire 5400 without having commanded the output, it assumes something outside its control is feeding power into that circuit or that the output driver itself is misbehaving. To protect the attachment and the controller, it disables the "G" output entirely, so the attachment tied to that circuit will not function until the fault clears.
The blinking ACD/RACD icon on the right instrument panel is your first visual clue. This code applies across the S510 through S770 skid steer models and T550 through T870 track loader models that use the ACD/RACD attachment control system.
Common causes of A8602
- Circuit output "G" wire 5400 to the attachment solenoid is shorted to a power source, feeding unexpected voltage into the circuit even when the controller has not energized it.
- A fault in the ACD/RACD controller itself, either in the output driver logic or the voltage-sensing circuit for output "G".
- Moisture, corrosion, or pushed-back pins in the mainframe connector or the attachment control harness connector, which can create unintended contact between wire 5400 and a powered circuit.
- If the code is intermittent and not active at the time of testing, the cause may not be found right away. Probable intermittent causes include loose connections, corrosion, pushed-back pins, the controller, the wire harness, or a combination of these problems.
How to troubleshoot Bobcat A8602: first checks
- Confirm the key switch is in the run/enter position, since that is the condition required for the controller to evaluate this code, then check whether the ACD/RACD icon is actively blinking.
- Inspect the mainframe and attachment control harness connectors at wire 5400 for moisture, corrosion, or pins that have been pushed back out of their sockets. Repair or reseat any suspect connector.
- With the attachment output not commanded on, check wire 5400 for a short to a power source. Look for chafed insulation where the harness could be rubbing against a hot wire, battery feed, or other powered circuit.
- If nothing is found active, wiggle-test the harness and connectors at the mainframe and attachment ends while watching for the code to reappear, since an intermittent fault may only show up under vibration or flex.
- If wire 5400 and the connectors check out clean, suspect the ACD/RACD controller's output driver or voltage-sensing circuit and have it tested or substituted.
How the code clears
Once the short or connector problem is repaired, clear A8602 by cycling the key switch power off and back on. No separate reset procedure or software step is listed beyond a power cycle.
Affected models and serial ranges
A8602 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 A8602 mean on a Bobcat machine?
It means the ACD/RACD attachment controller detected voltage on output "G" (wire 5400) when it had not turned that output on itself. The controller shuts the output off and the attachment on that circuit will not run until the issue is fixed.
Why did my attachment on output G stop working?
The controller disables the "G" output as a protective response as soon as A8602 sets. This is intentional: it prevents an attachment solenoid from being energized by an unintended voltage source.
Can I still operate the machine with A8602 active?
The machine itself is not disabled, but the specific attachment function wired to output "G" will not work until the fault is cleared and power is cycled.
How is A8602 different from A8605 or A8606?
A8602 is a general "unexpected voltage present" fault on output G when the controller did not command it on. A8605 (short to battery) and A8606 (short to ground) describe more specific wiring faults on the same output. If you're chasing a different symptom pattern, such as the output reading a dead short rather than stray voltage, check those codes instead.
How does A8602 differ from A8607, the open circuit code?
A8607 sets when output "G" cannot complete its circuit at all (an open), which is essentially the opposite electrical failure from A8602. A8602 means the controller is seeing voltage it did not send, while A8607 means it is seeing no continuity where it expects some. If your attachment has no response and no stray voltage, A8607 is the more likely match.
Do I need a scan tool to diagnose A8602?
A Bobcat diagnostic display or scan tool helps confirm the code and watch its live status, but the core diagnosis is electrical: checking wire 5400 for shorts to a power source and inspecting connectors for corrosion or pushed-back pins.
What if the code won't come back when I test the machine?
Intermittent A8602 faults are common with connector corrosion or pushed-back pins. If the fault isn't active during testing, wiggle-test the harness and connectors under load or vibration, since the root cause may only show itself intermittently.