Code
P1611
HUMMER
P — Powertrain
Loss of CVRTD Serial Data
AI status
Completed
Completed
100%
Causes
- Open or short in serial/CAN wiring between CVRTD and network
- Faulty CVRTD module (internal failure)
- Poor or corroded connector pins or grounds at CVRTD or related modules
- Blown fuse or loss of module power or ground
- Faulty network module (BCM/ECM) or gateway not forwarding messages
- Intermittent connection due to vibration or damaged harness
Symptoms
- Related subsystem inoperative or displays warning (depending on CVRTD function)
- Illumination of MIL or communication/network warning lights
- Intermittent or permanent fault present
- Other modules reporting related communication codes or degraded operation
What to check
- Use a scan tool to confirm P1611 and view freeze-frame data and timestamps
- Scan network for other U- or P-codes indicating communication faults
- Visually inspect CVRTD connector and wiring for damage, corrosion, bent pins, or moisture
- Check fuses and power/ground circuits for the CVRTD (voltage and continuity)
- Backprobe CVRTD connector to confirm key-on Vb and a good ground
- Measure CAN/serial bus continuity and resistance between high and low terminals (should be ~60 ohms total when network powered off)
Signal parameters
- CAN bus differential voltage: idle ~2.5 V on CAN_H and CAN_L vs ground, differential ~0 V idle; active dominant pulses present when network active
- CAN bus termination: total ~60 ohms between CAN_H and CAN_L with ignition off (two 120Ω in parallel)
- Message rate: presence of CVRTD-specific message ID(s) at expected frequency (scan tool/oscilloscope)
- Module supply voltage: ~12 V key on (verify within 11–14 V)
- Ground continuity:
Diagnostic algorithm
- Read and record codes and freeze frame with a professional scan tool; note any related U-codes.
- Clear codes and attempt to reinitialize; see if P1611 returns immediately or intermittently.
- Identify physical location of CVRTD module and inspect connector, pins, and wiring for damage, corrosion, or bent terminals.
- Verify module power and ground at the connector (key on engine off) using a DVOM.
- Check fuses and any relay supplying the CVRTD circuit.
- Measure CAN/serial bus resistance between CAN_H and CAN_L with ignition off (expect ~60 Ω). If open or shorted, isolate wiring sections to find fault.
- If resistance OK, use an oscilloscope or advanced scan tool to observe CAN_H/CAN_L at the CVRTD connector while operating networked systems; confirm message activity and signal integrity.
- Perform a wiggle/pressure test on wiring and connectors while monitoring live data/messages to locate intermittent faults.
- If power/ground and bus signals are correct but no module messages exist, swap or bench-test the CVRTD (if available) or replace the module per manufacturer procedure.
- After repair or replacement, reprogram/reflash module if required by manufacturer, clear DTCs, and verify correct operation and that code does not return.
Likely causes
- Damaged or disconnected CVRTD connector
- Loss of power or ground at the CVRTD module
- Short to battery or ground on CAN/serial pair
- Corroded terminals inside connectors
- Faulty CVRTD module
Fault status
Status
Loss of serial/CAN data from the CVRTD module. The network controller stopped receiving expected messages from the CVRTD module; communication is missing or intermittent.
Repair difficulty: Medium
Diagnostic time: 1.0 - 2.5 hours
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Repair manuals
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138
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