Bobcat M7974 (79-74) Fault Code: Door Open
Also shown on the panel as 79-74
Door Open · ai-assisted, editor-reviewed · Last updated 2026-07-13
TL;DR
Bobcat code M7974, shown as 79-74 on the numeric panel and displayed as "door" on the left display panel, means the controller sees battery voltage on the door sensor circuit and has determined the cab door is open or the door sensor circuit is telling it so. While active, the gateway controller locks out lift and tilt functions. It is self resetting once the real condition (door open, bad sensor, or wiring fault) is corrected.
Medium severity. M7974 itself is not a mechanical failure, but it disables lift and tilt functions on the loader, which stops work until it is resolved. On its own it doesn't threaten the engine or hydraulic system, so it is rated Medium rather than High, but you can't run the machine's lift/tilt with it active.
What does Bobcat error code M7974 mean?
Bobcat's M7974 code fires when the left display panel sees battery voltage on the door sensor wire pair (labeled 4740/4750, 4710/4720, or 3620/3630 depending on model and harness revision). When the cab door is open, that wire carries battery voltage to the display panel, which then reports the condition to the gateway controller over the CAN communication wires.
As soon as the gateway controller sees that supply voltage on the door sensor signal, it locks out lift and tilt functions as a safety measure, and the word "door" appears on the left display panel. This is meant to stop the operator from raising or tilting the loader arms with the cab door open.
The code sets the same way across all affected models and wire numbering variants: the underlying logic is identical, only the specific wire numbers differ by machine harness.
Common causes of M7974
- Cab door is actually open.
- Door latch is misaligned, the gap between the switch and magnet is too wide, or the magnet is missing.
- The signal wire (4740/4750, 4710/4720, or 3620/3630 depending on model) is shorted to a supply voltage.
- Faulty door sensor.
- Moisture, corrosion, or pushed-back pins in the left display panel connectors, cab harness, door harness, or wiper 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 M7974: first checks
- Confirm the cab door is fully closed and the latch seats properly, not just resting against the frame.
- Inspect the door latch alignment and the gap between the switch and magnet; look for a missing magnet.
- Check the door sensor and its wiring for visible damage, then inspect connectors at the left display panel, cab harness, door harness, and wiper harness for moisture, corrosion, or pushed-back pins.
- With the key switch (run/enter) on and Press To Operate Loader (PTOL) enabled, verify whether the code is present or intermittent; if it clears with the door closed and reappears with the door open, the sensor circuit is working as designed and the issue is likely mechanical (latch/magnet) rather than electrical.
- If the code is intermittent and not active during testing, focus inspection on connector corrosion, loose connections, and pushed-back pins throughout the door and cab harnesses before suspecting the controller.
How the code clears
M7974 is self resetting. No separate clearing step, procedure, or reset sequence is listed. Once the door is closed and the sensor circuit reads correctly (or once the wiring/sensor fault is repaired), the code should clear on its own and lift/tilt lockout should release.
Affected models and serial ranges
M7974 appears in our records across 15 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 |
| 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 M7974 mean?
It means the left display panel detected battery voltage on the door sensor circuit, which normally happens when the cab door is open. The gateway controller responds by locking out lift and tilt functions and displaying "door" on the left display panel.
What is the panel number for M7974?
The numeric panel form is 79-74.
Why won't my Bobcat loader lift or tilt with this code active?
The gateway controller intentionally locks out lift and tilt functions whenever it sees supply voltage on the door sensor wire, since that condition is meant to indicate an open door. This is a safety lockout, not a hydraulic malfunction.
Do I need a scan tool to clear M7974?
No separate clearing procedure is listed. The code is self resetting once the door is closed and the sensor circuit reads correctly, or once the underlying wiring or sensor fault is fixed.
My door is closed but the code still shows. What should I check?
Check for a misaligned door latch, too wide a gap between the switch and magnet, or a missing magnet. Also inspect the signal wire for a short to supply voltage, check the door sensor itself, and look for moisture, corrosion, or pushed-back pins in the left display panel, cab harness, door harness, and wiper harness connectors.
The code comes and goes. Why can't the technician find the cause?
If the code is not active at the time of testing, the root cause may not be identifiable right away. Likely culprits for intermittent faults include loose connections, corrosion, pushed-back pins, the controller, the wire harness, or some combination of these.
Which Bobcat models can show M7974?
S510, S530, S550, S570, S590, S630, S650, S750, S770, T590, T630, T650, T750, T770, and T870 can all display this code, though the exact door sensor wire numbers differ by model.