Code
C1244
HUMMER
C — Chassis
Powertrain Indicated Engine Drag Control Malfunction
AI status
Completed
Completed
100%
Causes
- Loss of communication on CAN bus between powertrain control module (PCM) and ABS/ESC module
- Faulty ABS/ESC (EBCM) module or PCM
- Intermittent or open wiring/connectors between modules (CAN, ground, power)
- Failed wheel speed sensor(s) or erratic sensor signals
- Defective brake light/switch or clutch/park/neutral switches used for traction logic
- Low battery voltage or poor battery/charging system condition
Symptoms
- Traction control/ESC warning lamp ON
- Reduced engine power or limited engine torque intervention
- ABS/traction control functions disabled or intermittent
- Unexpected or increased engine braking behavior during deceleration
- Inconsistent or jerky braking/stability behavior at low speeds
- Related DTCs present in ABS or powertrain modules
What to check
- Read ABS and PCM for stored and pending trouble codes plus freeze frame data
- Check for active communication on the vehicle CAN networks (use scan tool to view module list)
- Inspect battery voltage and charging system; verify good ground connections
- Visually inspect ABS/PCM harnesses and connectors for corrosion, damage, or water intrusion
- Check wheel speed sensors and tone rings for damage, contamination, or missing teeth
- Verify brake switch and other related input switches operate correctly
Signal parameters
- CAN messages: engine torque request, engine speed (RPM), vehicle speed
- Wheel speed sensor voltages/pulses and frequency vs. vehicle speed
- Brake switch status (on/off)
- ABS wheel-speed derived vehicle speed vs. PCM vehicle speed
- Module health/heartbeat communication counts and timeouts
- Battery voltage and transient drops during engine cranking
Diagnostic algorithm
- Connect a capable scan tool to read codes and live data from PCM and ABS/ESC modules. Record freeze frame and related codes.
- Clear codes and perform a road test to attempt to re-create the fault while monitoring CAN messages, wheel speeds, engine torque request, and module communication status.
- If communication drop or mismatched data observed, inspect CAN bus wiring, splice points, and module connectors for corrosion, loose pins, or damage. Repair any faults and retest.
- Check battery and charging system; ensure stable voltage. Replace or charge battery if voltage is low or terminals corroded.
- Test brake switch operation and associated circuits. Replace or adjust as required.
- Test wheel speed sensors and tone rings at each wheel. Clean, repair, or replace defective sensors or damaged rings.
- If wiring and sensors are good but communication errors persist, swap or bench-test the ABS/ESC module (if dealer-level procedure available) or the PCM as appropriate, following manufacturer service procedures.
- Check for and apply any available module software updates/recalls. After repairs, clear codes and perform final road verification to confirm no reoccurrence.
Likely causes
- CAN bus communication fault between PCM and EBCM (most common)
- Faulty ABS/ESC module failing to interpret engine drag/torque data
- Corroded/damaged connector or wiring at ABS/PCM harness
- Intermittent wheel speed sensor or ABS tone ring issue
- Faulty brake switch sending incorrect state to stability system
Fault status
Status
Powertrain indicated engine drag/torque control data is invalid or not present; traction/stability control may be disabled.
Repair difficulty: Medium
Diagnostic time: 1-3 hours
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Repair manuals
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138
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