Bobcat H3648 (36-48) Fault Code: Multiple ACDs Present (Attachment Control Device)
Also shown on the panel as 36-48 · Also called Multiple ACD Conflict Error
Multiple ACDs Present (Attachment Control Device) · ai-assisted, editor-reviewed · Last updated 2026-07-13
TL;DR
H3648 (panel code 36-48) sets when the auxiliary controller sees more than one Attachment Control Device (ACD) connected at the same time. It points to remote key wire 9400 or 3090 not grounding the ACD signal as it should. Cycle power once the wiring issue is fixed to clear the code.
Medium severity. H3648 does not describe an engine, hydraulic, or braking safety risk by itself. It is an attachment control communication fault. It matters because it can leave an attachment control device active or unresponsive, which is a concern any time an attachment is being operated, but it is a diagnose-it-this-shift issue rather than a stop-immediately one.
What does Bobcat error code H3648 mean?
H3648, shown on the panel as 36-48, is Bobcat's code for a Multiple ACD Conflict Error, meaning the auxiliary controller has detected more than one Attachment Control Device (ACD) connected to the machine at once. The ACD is the module that lets a powered attachment talk to the loader's control system.
The ACD communicates through the gateway controller to the auxiliary controller over CAN communication wiring (identified in the harness as the 91xx/95xx and 92xx/96xx wire groups). Part of that setup depends on a remote key wire, either 9400 or 3090 depending on the machine's wiring revision, grounding the ACD correctly.
When that remote key wire fails to ground the ACD, the ACD stays active instead of releasing, and the controller reads this as two ACDs present at the same time. That conflict is what triggers H3648.
What triggers a Bobcat H3648 code?
The code is set with the key switch (run/enter) on. No separate voltage, time, or count threshold is listed beyond that condition.
Common causes of H3648
- Remote key wire 9400 or 3090 (depending on machine wiring) open, so it cannot ground the ACD signal.
- A fault in the attachment harness itself.
- A fault in the 7-pin or 14-pin attachment harness on the loader.
- A fault in the 7-pin or 14-pin selector switch, on machines equipped with one.
- Moisture, corrosion, or pushed-back pins in the gateway controller connectors, attachment harness, ACD connector, or mainframe harness.
- An intermittent condition: if the code is not active at the time of testing, the cause may not be found right away. Probable causes in that case include loose connections, corrosion, pushed-back pins, the controller itself, the wire harness, or a combination of these.
How to troubleshoot Bobcat H3648: first checks
- Confirm the key switch is in run/enter and note whether H3648 is active now or was logged as historical/intermittent.
- Inspect the attachment harness end to end, including the 7-pin or 14-pin connector on the loader, for damage, bent pins, or loose connections.
- If the machine has a 7/14 pin selector switch, check its wiring and connections for continuity and secure seating.
- Check the gateway controller connectors, ACD connector, and mainframe harness connectors for moisture, corrosion, or pins that have been pushed back out of their sockets.
- Trace and test the remote key wire (9400 or 3090, depending on wiring revision) for continuity and confirm it grounds the ACD as designed.
- If no fault is found and the code is intermittent, recheck all connections above rather than assuming the controller is bad; the harness and connectors are the most common intermittent culprits.
How the code clears
Once the wiring or connector issue is repaired, clear H3648 by cycling power on the machine (key off, then back on). No separate reset procedure is listed beyond this power cycle.
Affected models and serial ranges
H3648 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, SN A3PH11001-99999 |
Frequently asked questions
What does Bobcat code H3648 mean?
It means the auxiliary controller has detected more than one Attachment Control Device (ACD) connected at once, usually because a remote key wire (9400 or 3090) is not grounding the ACD signal the way it should.
What is the panel display number for H3648?
On the dash panel it shows as 36-48.
Is H3648 dangerous to keep operating with?
It is not described as an engine or structural safety fault, but because it involves attachment control communication, it should be diagnosed before relying on powered attachment functions, especially if attachment behavior seems inconsistent.
Which Bobcat models can show code H3648?
It applies to S510, S530, S550, S570, S590, S630, S650, S750, S770, T550, T590, T630, T650, T750, and T770 skid steers and track loaders, as well as T870.
How do I clear H3648 after a repair?
Cycle the key switch off and back on once the wiring or connector fault causing the multiple ACD conflict is fixed. No other reset step is listed.
Why would the controller see two ACDs when only one attachment is hooked up?
If the remote key wire that is supposed to ground the ACD signal is open or corroded, the ACD can stay electrically active instead of dropping out cleanly, which the controller interprets as a second ACD being present.
The code only shows up sometimes. What should I check?
Intermittent H3648 is usually tied to loose connections, corrosion, or pushed-back pins in the attachment harness, gateway controller connector, ACD connector, or mainframe harness. Check all of these carefully even if the code is not active during testing.