Bobcat A8402 (84-02) Fault Code: ACD/RACD Output "E" Error On
Also shown on the panel as 84-02 · Also called ACD Output ‘E’ Error On
ACD/RACD Output "E" Error On · ai-assisted, editor-reviewed · Last updated 2026-07-13
TL;DR
Bobcat fault code A8402, shown as 84-02 on the panel, means the ACD/RACD controller found voltage on output "E" wire 5100 when it never sent voltage to energize the attachment solenoid coil. The controller shuts off that electric output, the attachment on output "E" stops working, and the ACD/RACD icon on the right instrument panel blinks.
Medium severity. The attachment on output "E" is disabled until the fault is fixed, but the machine itself stays drivable and there is no indication of engine, hydraulic, or structural damage risk. Treat it as a functional problem to diagnose during the shift rather than an emergency stop.
What does Bobcat error code A8402 mean?
A8402 is an ACD/RACD (Attachment Control Device / Remote Attachment Control Device) fault. The ACD/RACD controller manages power to attachment solenoids so implements like grapples, sweepers, or other hydraulically actuated tools switch on and off correctly from the cab.
This code sets when the controller sees voltage present on output "E" (wire 5100) at a time when it has not commanded that output on. In other words, the controller expects zero volts on that circuit and finds voltage anyway, which points to unwanted power reaching the wire from somewhere else.
Once the code goes active, the controller protects the circuit by shutting off the output entirely. The attachment wired to output "E" will not function, and the operator sees a blinking ACD/RACD icon on the right instrument panel as the warning.
Common causes of A8402
- Output "E" wire 5100 to the attachment solenoid is shorted to a power source, feeding voltage into the circuit even when the controller has not energized it.
- A fault in the ACD/RACD controller itself.
- Moisture, corrosion, or pushed-back pins in the mainframe or attachment control harness connectors.
- If the code is intermittent and not active at the time of testing, the exact cause may not be found right away. Probable causes in that case include loose connections, corrosion, pushed-back pins, the controller, the wire harness, or a combination of these problems.
How to troubleshoot Bobcat A8402: first checks
- Turn the key switch to run/enter (the condition needed for the code to be present) and check whether the ACD/RACD icon on the right instrument panel is blinking.
- Inspect the mainframe and attachment control harness connectors for moisture, corrosion, or pins that have been pushed back out of their sockets.
- Trace wire 5100 from the ACD/RACD controller output "E" to the attachment solenoid and look for chafed insulation or contact with a power source that could be feeding voltage back into the circuit.
- Check connections at the controller and along the harness for looseness, since loose connections are listed as a probable cause, especially for intermittent codes.
- If the code is not active during testing, treat it as intermittent and inspect all of the listed probable causes: loose connections, corrosion, pushed-back pins, the controller, and the wire harness.
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
A8402 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 A8402 mean?
It means the ACD/RACD controller detected voltage on output "E" (wire 5100) when it had not sent voltage to energize the attachment solenoid coil. The controller shuts that output off and the attachment on output "E" will not work until the fault is fixed.
What is the panel display for A8402?
On the instrument panel it shows as 84-02, and the ACD/RACD icon on the right instrument panel blinks while the code is active.
Will my attachment still work with code A8402 active?
No. While A8402 is active, the ACD/RACD electric output is shut off, so the attachment wired to output "E" will not function.
What usually causes this code?
The main causes are wire 5100 shorted to a power source, a fault in the ACD/RACD controller, or moisture, corrosion, or pushed-back pins in the mainframe or attachment control harness connectors.
The code isn't active now, does that mean it's fixed?
Not necessarily. If the code is intermittent and not on at the time of testing, the cause may not be found immediately. Loose connections, corrosion, pushed-back pins, the controller, or the wire harness can all cause an intermittent version of this fault.
How do I clear A8402 after repair?
Cycle power to the machine. That is the only clearing step listed for this code.
Which Bobcat machines can show code A8402?
It applies to S510, S530, S550, S570, S590, S630, S650, S750, S770, T550, T590, T630, T650, T750, and T770 models, among the affected models listed for this code.