Code
C0362
HUMMER
C — Chassis
4LO Discrete Output Circuit High
AI status
Completed
Completed
100%
Causes
- Short to battery (B+) on the 4LO output circuit
- Stuck or welded relay contacts powering the 4LO circuit
- Failed transfer case actuator / solenoid that pulls circuit high
- Damaged, chafed or pinched wiring harness (insulation worn through)
- Corroded or loose connector pins causing unintended continuity to B+
- Internal failure of the transfer case control module / output driver
Symptoms
- Inability to shift into 4LO or loss of 4LO functionality
- 4WD/transfer case warning lamp or message displayed
- Stored DTC C0362 (may be accompanied by other transfer case DTCs)
- Intermittent or constant unexpected 12V on output harness
- Reduced drivetrain functionality or limp-home mode in some vehicles
What to check
- Retrieve all stored codes and freeze/frame data with a scan tool
- Visual inspection of harness, connectors, and transfer case area for damage, corrosion, or water
- Measure voltage at the 4LO output pin at the transfer case connector with ignition ON and with output commanded OFF/ON
- Backprobe the control module output connector to compare module-side vs harness-side voltages
- Check continuity to battery (+) and to ground for unintended shorts with power removed
- Unplug the 4LO actuator/solenoid and re-check the circuit voltage and DTC
Signal parameters
- Expected OFF state: ~0 V (or near ground) on the output circuit
- Expected ON state: battery voltage (~9–14 V) at the actuator/relay feed when commanded ON
- Fault condition: elevated voltage at the output when the controller is commanding OFF (voltage close to battery)
- Typical current draw: actuator/solenoid may draw from tens of mA up to a few amps depending on design (measure actual draw)
- Module output driver may be low-side switching (pull to ground) or high-side switching — verify wiring and service manual
Diagnostic algorithm
- Read and record all DTCs and freeze data. Attempt to clear codes and see if C0362 returns.
- Perform a visual inspection of wiring and connectors at the transfer case and along the harness for damage, corrosion, or water entry.
- With ignition ON (engine off), backprobe the transfer case 4LO output at the connector. Note voltage with the controller commanding the output OFF. If voltage is near battery, suspect short to B+ or stuck relay/actuator.
- Command the 4LO output ON via a capable scan tool. Verify the output changes state (voltage goes to expected ON level) and observe actuator operation. If output cannot be commanded or reading is inconsistent, continue diagnostics.
- Disconnect the actuator/solenoid and check the output voltage again while commanded OFF. If voltage remains high with the actuator disconnected, the fault is upstream (wiring or module). If voltage returns to normal when actuator is unplugged, suspect the actuator is shorted or internally conducting.
- Inspect and test related relays (swap with a known-good relay if applicable) and check for welded contacts that could feed battery voltage to the circuit.
- With battery disconnected and using an ohmmeter, check for continuity between the 4LO output circuit and battery positive to confirm a short. Also check continuity to ground where applicable.
- If wiring and connectors test good, and the output behaves incorrectly at the module connector, consider module output driver failure — consult factory service information before module replacement and verify pin-level behavior per wiring diagram.
- After repairs, clear codes and verify proper operation by commanding 4LO ON/OFF and road-testing in a safe environment if required.
Likely causes
- Short to B+ at connector or damaged harness near transfer case
- Corroded connector allowing backfeed of battery voltage
- Faulty 4LO solenoid/actuator partially conducting when off
- Failed output transistor inside transfer case control module
- Stuck relay supplying constant battery voltage to the circuit
Fault status
Status
4LO discrete output circuit high — control module detected a higher-than-expected voltage on the 4LO output circuit indicating a possible short to battery, faulty actuator/relay, wiring or module driver issue.
Repair difficulty: Medium
Diagnostic time: 0.5-2.0 hours
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