Bobcat H2606 (26-06) Fault Code: Front Base Solenoid Short to Ground
Also shown on the panel as 26-06 · Also called Front Base Output Short to Ground, Front Base Solenoid Short To Ground, Front Base Solenoid Short to Ground
Front Base Solenoid Short to Ground · ai-assisted, editor-reviewed · Last updated 2026-07-13
TL;DR
H2606 (panel form 26-06) sets when the auxiliary controller commands the front base solenoid but does not detect voltage on signal wire 4340 or return wire 2340 (or on wire 4100 / 2100 on deluxe MX controller machines), typically because that circuit is shorted to ground. The front base solenoid is disabled when this code is active, so front auxiliary hydraulic flow through the front auxiliary female coupler stops working.
Medium severity. This code disables the front base auxiliary solenoid, so any attachment relying on front auxiliary hydraulic flow will not function until the fault is fixed. It does not by itself indicate an immediate safety emergency, but running with a shorted circuit risks further wiring or controller damage and leaves attachment control unreliable.
What does Bobcat error code H2606 mean?
H2606 is Bobcat's code for a Front Base Solenoid Short to Ground condition. It is set by the auxiliary controller (or, on some machines, the deluxe MX controller) when it commands the front base solenoid on but does not see the expected voltage return on the signal or return wire for that circuit.
The front base solenoid directs hydraulic flow through the front auxiliary female coupler, the connection point most attachments use for front-facing hydraulic function. When the controller can't confirm the circuit is behaving correctly, most likely because the signal or return wire is shorted to ground, it shuts the front base solenoid off as a protective measure.
With the solenoid disabled, the attachment function tied to that coupler will not operate. The rest of the machine's auxiliary hydraulics may still work depending on what else is affected.
Common causes of H2606
- Signal wire 4340 or return wire 2340 shorted to ground (or wires 4100 / 2100 on machines with the deluxe MX controller).
- Faulty front base solenoid.
- Fault in the auxiliary controller, or in the deluxe MX controller on equipped machines.
- Moisture, corrosion, or pushed-back pins in the auxiliary controller connectors, front base solenoid connector, the mainframe harness, or on deluxe MX machines the deluxe MX power harness or control harness.
- Intermittent wiring or connection issues, loose connections, corrosion, or pushed-back pins in combination, which may not show up if the code isn't active at the time of testing.
How to troubleshoot Bobcat H2606: first checks
- Confirm the key switch is in the run/enter position, auxiliaries are enabled, and a front base command is actually being given, since these are the conditions required for the code to set.
- Inspect the front base solenoid connector and the mainframe harness connectors (or deluxe MX power/control harness connectors on equipped machines) for moisture, corrosion, or pushed-back pins.
- Check signal wire 4340 and return wire 2340 (or 4100 / 2100 on deluxe MX machines) for chafing, pinched insulation, or contact with ground at any point along the harness.
- Test the front base solenoid itself for a short to ground or internal fault.
- If the code is not active during testing, treat it as intermittent and recheck all connectors and harness routing for loose connections, corrosion, or pushed-back pins, since the root cause may not be found unless the code is present at the time of inspection.
How the code clears
Once the repair is complete, clear the code by cycling the key switch power off and back on. No separate clearing step is listed beyond a power cycle.
Affected models and serial ranges
H2606 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 H2606 mean?
It means the auxiliary controller commanded the front base solenoid on but did not detect the expected voltage on the signal wire (4340) or return wire (2340), usually because that circuit is shorted to ground. The controller responds by disabling the front base solenoid.
What is the panel display number for H2606?
The numeric panel form of H2606 is 26-06.
Will my attachment stop working with this code active?
Yes. When H2606 is active, the front base solenoid is disabled, so hydraulic flow through the front auxiliary female coupler will not be directed as commanded, affecting any attachment function using that circuit.
Which Bobcat machines can show code H2606?
This code applies to a range of Bobcat models including the E35, E45, S510, S530, S550, S570, S590, S630, S650, S750, S770, T550, T590, T630, T650, T750, and T770 skid steers and compact track loaders, as well as the T870.
How do I clear H2606 after fixing the problem?
Cycle the key power off and back on. No other clearing procedure is listed.
Why does the code sometimes not show up during testing?
If the short or connection fault is intermittent, the code may not be active at the time you check it. In that case the cause may not be found immediately, and you should recheck connectors and harness routing for loose connections, corrosion, or pushed-back pins.
Is H2606 the same as a code involving wires 4100 and 2100?
On machines equipped with the deluxe MX controller, the same H2606 code description applies but references signal wire 4100 and return wire 2100 instead of 4340 and 2340. The underlying fault, a short to ground on the front base solenoid circuit, is the same.