Bobcat M3505 (35-05) Fault Code: Hydraulic Fan Solenoid Error On
Also shown on the panel as 35-05 · Also called Hydraulic Fan Short to Battery
Hydraulic Fan Solenoid Error On · ai-assisted, editor-reviewed · Last updated 2026-07-13
TL;DR
M3505 (panel code 35-05) sets when the Bobcat gateway controller sees battery voltage on the hydraulic fan solenoid signal wire 4010 while it has not commanded the fan on. It points to a short to battery voltage somewhere in the fan solenoid circuit, the solenoid itself, or the gateway controller.
Medium severity. The hydraulic fan cooling function can be affected, and an unwanted short-to-battery condition on a solenoid circuit can eventually damage the controller output driver or the solenoid. It is not an immediate stop-work code, but it should be diagnosed before running the machine hard or in hot conditions.
What does Bobcat error code M3505 mean?
A code M3505 occurs when the gateway controller detects battery voltage on the hydraulic fan solenoid signal wire 4010 when the controller has not commanded the fan on. Normally the gateway controller energizes the hydraulic fan solenoid based on engine temperature or hydraulic temperature. When the controller instead sees battery voltage present on that circuit at a time it should be off, it flags M3505.
This is an electrical circuit fault, not a direct reading of fan speed or cooling performance. The controller is comparing what it expects to see on the fan solenoid wiring against what is actually there, and a mismatch caused by a short to battery voltage triggers the code.
Because the hydraulic fan is tied to cooling for both engine and hydraulic oil temperature control, a stuck-on or miswired fan circuit can affect cooling behavior, wiring integrity, and controller output life if left unaddressed.
Common causes of M3505
- Controller output wire 4010 shorted to battery voltage.
- Return wire 2910 shorted to supply voltage or shorted to signal wire 4010.
- A failed hydraulic fan solenoid.
- A failed gateway controller.
- Moisture corrosion or pushed-back pins in the gateway controller connectors, the hydraulic fan solenoid connector, or the mainframe harness.
- Intermittent causes if the code is not active at the time of testing: loose connections, corrosion, pushed-back pins, the controller, the wire harness, or a combination of these problems.
How to troubleshoot Bobcat M3505: first checks
- With the key switch / run-enter switch on (the condition under which the code is set), check for the code's presence and note whether it is active or intermittent.
- Inspect the hydraulic fan solenoid connector and the gateway controller connectors for moisture, corrosion, or pushed-back pins.
- Check the mainframe harness along the run of wire 4010 and wire 2910 for chafing, pinches, or shorts to battery voltage or to each other.
- Test wire 4010 for a short to battery voltage and wire 2910 for a short to supply voltage or to wire 4010.
- If no fault is found and the code is intermittent, inspect all connections in the circuit again, since intermittent faults may not be reproducible at the time of testing.
- If wiring and connectors check out, test the hydraulic fan solenoid and the gateway controller output for the circuit.
How the code clears
Clearing the code requires cycling power (turning the key switch off and back on) after the repair is complete. No separate clearing step is listed beyond cycling power.
Affected models and serial ranges
M3505 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-ATZC99999 |
| 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 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 M3505 mean?
It means the gateway controller detected battery voltage on the hydraulic fan solenoid wire (wire 4010) at a time when the controller had not commanded the fan solenoid on. This points to a short to battery voltage in that circuit, a bad solenoid, or a controller fault.
What is the panel display version of M3505?
On the display panel it shows as 35-05.
Which Bobcat machines can show code M3505?
It applies to S510, S530, S550, S570, S590, S630, S650, S750, S770, T550, T590, T630, T650, T750, and T770/T870 skid steer and track loader models.
Can I clear M3505 myself after a repair?
Yes. Once the repair is complete, cycle the key switch power off and back on. No separate clearing procedure is listed.
Is it safe to keep running the machine with M3505 active?
There is no listed immediate shutdown requirement, but since the fault involves a short to battery voltage on a solenoid circuit, it should be diagnosed promptly to avoid damaging the gateway controller output or affecting hydraulic and engine cooling.
Why does the code come and go instead of staying on?
An intermittent M3505 usually points to loose connections, corrosion, or pushed-back pins in the connectors rather than a solid short. If the code is not active when you test, recheck all connectors and harness sections in the circuit since the cause may not be visible at that moment.
What wires are involved in M3505?
Wire 4010 is the controller output/signal wire to the hydraulic fan solenoid, and wire 2910 is the return wire. The code sets from a short to battery voltage on wire 4010 or a short involving wire 2910 to supply voltage or to wire 4010.