Case IH 1522 – UCM (Universal Control Module): Left Brake Light Actuation: Short to Ground

The electrical circuit supplying power to the left brake light has a short circuit to the machine's chassis/ground, preventing the light from functioning properly and potentially blowing a fuse or triggering a module protection state. It is accompanied by a "white" telltale warning lamp on the dash.

• skid steer
• Skid Steer Loaders (SSL)
• Compact Track Loaders (CTL)
• SR130
• SR150
• SR160
• SR175
• SR200
• SR210
• SR220
• SR240
• SR250
• SR270
• SV185
• SV250
• SV280
• SV300
• SV340
• TR270
• TR310
• TR320
• TR340
• TV370
• TV380
• TV450

1. 1

   Inspect the left rear tail light assembly for physical damage, water intrusion, or a melted bulb socket, which commonly causes internal shorts.

2. 2

   Trace the wiring harness from the left brake light back toward the UCM. Look for pinched wires, chafing against the frame, or exposed copper touching bare metal (ground).

3. 3

   Disconnect the left brake light pigtail. Use a digital multimeter to check the power supply wire for continuity to ground. If continuity to ground exists while disconnected, the short is in the harness. If it does not, the short is internal to the light assembly.

4. 4

   Inspect the UCM connectors for corrosion, bent pins, or moisture that could be bridging the brake light circuit to a ground pin.

1. 1

   Disconnect Power

   Turn off the machine and disconnect the negative battery cable to prevent electrical spikes.

2. 2

   Isolate the Fault

   Based on the diagnostic checks, locate the exact point of the short.

3. 3

   Repair Wiring

   If the harness is chafed, cut out the damaged section of wire, solder in a new section, and seal it with marine-grade heat shrink tubing. Secure the harness away from pinch points using zip ties.

4. 4

   Replace Light Assembly

   If the short is inside the light housing or socket, unbolt the old tail light assembly, disconnect the plug, and install the replacement unit.

5. 5

   Test

   Reconnect the battery, turn the key on, and actuate the brakes. Verify that the left brake light illuminates and that the 1522 fault code changes to an inactive state or clears from the dash.