Bobcat M1805 (18-05) Fault Code: Lift Spool Lock Short to Battery
Also shown on the panel as 18-05 · Also called Lift Spool Lock Output Short to Battery
Lift Spool Lock Short to Battery · ai-assisted, editor-reviewed · Last updated 2026-07-13
TL;DR
M1805 sets when the gateway controller sees battery voltage on the lift spool lock signal wire (4680 or 4380 depending on model) while the seatbar is up and the circuit was not commanded on. When it sets, lift and tilt are disabled until the fault is fixed and power is cycled.
High severity. The machine loses lift and tilt function as soon as this code sets, which stops loader work immediately. It is not a safety-critical failure in the sense of brakes or steering, but it takes the machine out of service until repaired.
What does Bobcat error code M1805 mean?
M1805 is triggered when the gateway controller detects battery voltage present on the lift spool lock signal wire, either wire 4680 or wire 4380 depending on the model, at a time when the controller has not commanded that output on. In plain terms, the controller expects that circuit to be off and instead sees full voltage on it.
The lift spool lock solenoid is part of the hydraulic control that locks out lift and tilt movement when conditions require it (such as seatbar position). If the controller sees unexpected voltage on this circuit, it cannot trust the lock state, so as a safety measure it disables both lift and tilt entirely.
This code is only detected while the seatbar is up. If the seatbar is down, the condition that triggers this check is not evaluated.
What triggers a Bobcat M1805 code?
The gateway controller sets M1805 when it detects battery voltage on the lift spool lock signal wire (4680 or 4380) while that output has not been commanded on, and only while the seatbar is up. Conditions for the code to be checked are key switch (run/enter) on and seatbar up.
Common causes of M1805
- Signal wire (4680 or 4380, depending on model) shorted to battery voltage.
- Return wire (2680 or 2380) shorted to supply voltage, or shorted to the signal wire.
- Faulty lift spool lock solenoid.
- Faulty gateway controller.
- Moisture, corrosion, or pushed-back pins in the gateway controller connectors, the lift spool lock solenoid connector, or the mainframe harness.
- Intermittent fault: if the code is not active at the time of testing, the cause may not be found immediately. Probable causes in these cases include loose connections, corrosion, pushed-back pins, the controller itself, the wire harness, or a combination of these.
How to troubleshoot Bobcat M1805: first checks
- Confirm the seatbar is up and key switch is on, since these are the required conditions for the code to be evaluated.
- Inspect the gateway controller connectors, the lift spool lock solenoid connector, and the mainframe harness connectors for moisture, corrosion, or pushed-back pins.
- Check the signal wire (4680 or 4380 depending on your model) for a short to battery voltage.
- Check the return wire (2680 or 2380) for a short to supply voltage or a short to the signal wire.
- Test the lift spool lock solenoid for proper operation and resistance.
- If the code is not currently active, treat it as intermittent and focus on loose connections, corrosion, and connector pin condition throughout the circuit before suspecting the controller itself.
How the code clears
After the repair is complete, cycle power (turn the key switch off, then back on) to clear the code. No separate clearing step is listed.
Affected models and serial ranges
M1805 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 M1805 mean?
It means the gateway controller detected battery voltage on the lift spool lock signal wire (wire 4680 or 4380 depending on model) when that circuit was not commanded on, while the seatbar was up. This disables lift and tilt function.
Why did my loader lose lift and tilt with no other warning?
If M1805 sets, the controller automatically disables lift and tilt as a protective response because it can no longer trust the state of the lift spool lock circuit. This is expected behavior for this fault, not a separate mechanical failure.
Which wire is affected, 4680 or 4380?
It depends on the model. Some Bobcat models use wire 4680 for the lift spool lock signal, others use wire 4380. Check your machine's wiring diagram to confirm which applies to your unit.
Will clearing the code bring back lift and tilt?
Only after the underlying short or fault is actually repaired. Once the repair is done, cycle power (key off, then on) to clear the code. Simply cycling power without fixing the short will likely bring the code right back.
Can a loose connector cause this code intermittently?
Yes. Moisture, corrosion, or pushed-back pins in the gateway controller connectors, the solenoid connector, or the mainframe harness are all listed causes, and these can produce an intermittent version of the fault that is hard to catch if it is not active during testing.
Does the seatbar position matter for this code?
Yes. M1805 is only detected while the seatbar is up. If the seatbar is down, this particular check is not being evaluated by the controller.
Is this a controller problem or a wiring problem?
It can be either. Possible causes include the signal wire shorted to battery voltage, the return wire shorted to supply or to the signal wire, a faulty lift spool lock solenoid, or a faulty gateway controller itself. Wiring and connector issues should be ruled out first since they are the most common and cheapest to fix.