Bobcat H2605 (26-05) Fault Code: Front Base Solenoid Short to Battery
Also shown on the panel as 26-05 · Also called Front Base Output Short to Battery, Front Base Solenoid Short To Battery, Front Base Solenoid Short to Battery
Front Base Solenoid Short to Battery · ai-assisted, editor-reviewed · Last updated 2026-07-13
TL;DR
H2605 (panel code 26-05) sets when the auxiliary controller, or on some machines the deluxe MX controller, detects battery voltage on the front base solenoid signal wire when the solenoid is not commanded on. The front base solenoid, which directs hydraulic flow through the front auxiliary female coupler, gets disabled until the fault clears.
Medium severity. Front auxiliary hydraulic flow to the front coupler is disabled while this code is active, which stops any front-mounted attachment that relies on that circuit from working. It is not a driving or engine safety hazard by itself, but it will halt attachment work until fixed.
What does Bobcat error code H2605 mean?
H2605 is a Bobcat fault code that fires when the auxiliary controller (or the deluxe MX controller on machines equipped with that system) sees battery voltage present on the front base solenoid's signal wire at a time when it did not command that voltage. In plain terms, the controller expects to control this wire itself, and instead finds voltage already there, which looks like a short to battery power somewhere in the circuit.
The front base solenoid's job is to direct hydraulic flow out through the front auxiliary female coupler, which is what powers front-mounted attachments. Once the controller detects this fault condition, it disables the front base solenoid (and on deluxe MX controller machines, it disables the auxiliaries generally) as a protective measure so the circuit cannot behave unpredictably.
Common causes of H2605
- Signal wire (4340 on auxiliary controller machines, or 4100 on deluxe MX controller machines) shorted to battery voltage
- Return wire (2340, or 2100 on deluxe MX machines) shorted to supply voltage or shorted to the signal wire
- Front base solenoid fault
- Auxiliary controller fault, or deluxe MX controller fault on equipped machines
- Moisture, corrosion, or pushed-back pins in the auxiliary controller connectors, front base solenoid connector, mainframe harness, or on deluxe MX machines the deluxe MX power harness or control harness
- Intermittent fault: if the code is not active at the time of testing, the cause may not be found immediately. Probable causes in this case include loose connections, corrosion, pushed-back pins, the controller itself, the wire harness, or a combination of these
How to troubleshoot Bobcat H2605: first checks
- Turn the key switch to run/enter, since this is the condition under which the code is set, and confirm whether the code is currently active or was only historical/intermittent
- Inspect the front base solenoid connector and the auxiliary controller (or deluxe MX controller) connectors for moisture, corrosion, or pins that have pushed back out of the connector body
- Check signal wire 4340 (or 4100 on deluxe MX machines) for a short to battery voltage anywhere along its run
- Check return wire 2340 (or 2100 on deluxe MX machines) for a short to supply voltage or for chafing against the signal wire
- Inspect the mainframe harness, and on deluxe MX equipped machines the deluxe MX power harness and control harness, for damage, rubbing points, or pinched sections
- If the code will not reproduce, treat it as intermittent and focus on loose connections, corrosion, and pushed-back pins before condemning the controller
How the code clears
Bobcat lists cycling power as the condition for clearing this code once the repair is complete. Turn the key switch off, then back to run/enter, after the wiring or component repair has been made.
Affected models and serial ranges
H2605 appears in our records across 18 Bobcat models. Match your machine by model and serial number.
| Model | Serial ranges |
|---|---|
| E35 | SN A93K110001-99999, SN AC2P11001-99999 |
| E45 | SN AHHC11001-99999 |
| 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 H2605 mean?
It means the auxiliary controller, or the deluxe MX controller on equipped machines, detected battery voltage on the front base solenoid signal wire when it had not commanded that voltage. This looks electrically like a short to battery power in that circuit.
What happens to the machine when H2605 is active?
The front base solenoid is disabled, which shuts off directed hydraulic flow through the front auxiliary female coupler. On deluxe MX controller machines, the auxiliaries as a whole are disabled while the code is active.
Which Bobcat machines can show code H2605?
It applies across a range of excavator and loader models including the E35, E45, S510, S530, S550, S570, S590, S630, S650, S750, S770, T550, T590, T630, T650, T750, and T770.
Is H2605 the same as panel code 26-05?
Yes. H2605 is the alphanumeric fault code, and 26-05 is the same fault shown in the older numeric panel display format.
Why does H2605 keep coming back even after I clear it?
Intermittent shorts caused by corrosion, moisture, loose connections, or pushed-back pins in the connectors or harness can cause the code to set only under certain conditions, then clear on power cycle without the underlying wiring problem being fixed. If it returns, recheck every connector in the circuit rather than assuming it is fixed.
How do I clear code H2605 after repair?
Cycle the key switch off and back to run/enter. That is the only clearing condition listed for this code once the wiring or component issue has been corrected.
Can I keep working with H2605 active?
You can generally still operate the machine, but the front auxiliary hydraulic function tied to the front base solenoid and front coupler will not work, so any attachment relying on that circuit will be inoperable until the fault is fixed.