Bobcat A8603 (86-03) Fault Code: ACD/RACD Output "G" Error Off
Also shown on the panel as 86-03 · Also called ACD Output ‘G’ Error Off
ACD/RACD Output "G" Error Off · ai-assisted, editor-reviewed · Last updated 2026-07-13
TL;DR
A8603 (panel display 86-03) sets when the ACD/RACD controller sends voltage out on output "G" wire 5400 to energize an attachment solenoid coil but detects no voltage return, or shuts the output off after sensing a large current draw. The ACD/RACD icon on the right instrument panel will blink, and the attachment connected to output "G" will not function.
Medium severity. The affected attachment function on output "G" will stop working, which can be a real problem depending on the attachment in use, but the machine itself remains drivable and other systems are unaffected. Treat it as a diagnose-this-shift issue rather than an emergency stop.
What does Bobcat error code A8603 mean?
A8603 is set by the Advanced Combination Deflector or Reverse Advanced Combination Deflector (ACD/RACD) controller, the module that manages attachment solenoid outputs. When the controller energizes output "G" to run an attachment solenoid coil, it expects to see voltage on wire 5400. If that voltage doesn't show up, or if the controller detects a large current draw and shuts the output off to protect itself, it logs A8603 and blinks the ACD/RACD icon on the right instrument panel.
This is fundamentally an electrical circuit fault, not a hydraulic or mechanical failure inside the attachment itself. The controller is telling you that the command it sent out did not come back the way it should, which usually points to a short, an open, or a bad connection somewhere between the controller and the solenoid coil.
Common causes of A8603
- Shorted solenoid coil on the attachment connected to output "G".
- Circuit output "G" wire 5400 shorted to ground between the controller and the attachment solenoid.
- A fault in the ACD/RACD controller itself.
- Moisture, corrosion, or pushed-back pins in the mainframe or attachment control harness connectors.
- Loose connections or a combination of loose connections, corrosion, and pushed-back pins in the wire harness (especially likely if the code is intermittent and not active at the time of testing, which can make the exact cause hard to pin down on a single inspection).
How to troubleshoot Bobcat A8603: first checks
- Confirm the key switch is in the run/enter position, since this is the condition required for the controller to set the code, then check whether the ACD/RACD icon on the right instrument panel is blinking.
- Inspect the attachment solenoid coil for a short: check resistance and look for obvious damage, melted insulation, or signs of overheating.
- Trace circuit output "G" wire 5400 from the controller to the attachment solenoid connector, checking for chafed insulation or a short to ground anywhere along the run.
- Disconnect and inspect all mainframe and attachment control harness connectors in this circuit for moisture intrusion, corrosion on the pins, or pins that have been pushed back out of their proper seated position.
- If the code is not currently active, wiggle-test connectors and harness sections while watching for the fault to reappear, since intermittent faults from loose connections or corrosion may not show up during a static check.
How the code clears
Once the repair is complete, cycle the key power off and back on. No separate clearing step is listed beyond cycling power.
Affected models and serial ranges
A8603 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 A8603 mean?
It means the ACD/RACD controller sent voltage out on output "G" (wire 5400) to energize an attachment solenoid coil but did not see the expected voltage return, or the controller cut the output after sensing excessive current draw. The result is that the attachment on output "G" stops working and the ACD/RACD icon blinks on the right instrument panel.
Is A8603 the same as fault 86-03?
Yes. 86-03 is simply the numeric panel display form of the same code, A8603.
Can I keep operating the machine with A8603 active?
The machine itself will still drive and operate normally, but the specific attachment function wired to output "G" will not work until the fault is fixed. Whether that's safe to work around depends on which attachment and function is affected.
Why does A8603 come and go instead of staying on?
Intermittent faults like this are usually caused by loose connections, corrosion, or pins pushed back in a connector that only fail under vibration, moisture, or specific harness positions. If the code isn't active when you test, the root cause may not show up right away, so a wiggle test on connectors while monitoring for the fault is a good next step.
What's the most common cause of A8603?
Bobcat lists a shorted solenoid coil, a short to ground on wire 5400, a faulty ACD/RACD controller, and connector issues such as moisture, corrosion, or pushed-back pins as the possible causes. There's no single most-likely cause identified, so each needs to be checked.
How do I clear code A8603 after fixing it?
Cycle the key power off and back on. No other reset procedure is listed.