P1611

Code

BUICK P — Powertrain

Loss Of CVRTD Serial Data

Brand: BUICK

Type: P — Powertrain

Views: UK: 22 EN: 37 RU: 24

AI status

Completed

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Page language: EN

Causes

Open or shorted wiring between the CVRTD module and the vehicle data bus
Poor or missing power or ground to the CVRTD module
Corroded, loose or damaged connector pins at the CVRTD module or junctions
Failed CVRTD module (internal electronics or firmware)
Data bus (CAN/GMLAN/Class 2) wiring fault or bus termination problem
Aftermarket radio, alarm or accessory interfering with serial bus

Symptoms

Related CVRTD-controlled features inoperative or intermittent (manufacturer-specific functions)
Illumination of warning lights or message center alerts about communication faults
Other modules showing communication or functionality faults
Stored communication fault P1611 and possibly related U-codes in other modules

What to check

Read and record all stored DTCs and freeze-frame data from all modules with a capable scan tool
Verify battery voltage is within 12.2–12.8V with ignition ON; check charging system if low
Visually inspect fuses related to the CVRTD module and data bus (replace if open)
Inspect CVRTD connector(s) and harness for corrosion, bent pins, water intrusion or damage
Verify good ground(s) at module chassis ground points
Check for recent aftermarket installations that tap the data bus or power circuits

Signal parameters

Data-bus physical layer: CAN/GMLAN/Class 2 depending on model (expect two-wire differential CAN: CAN_H ~2.5–3.5V, CAN_L ~1.5–2.5V when idle)
Bus termination: approx. 60 ohms total across CAN_H and CAN_L (two 120 ohm resistors in parallel)
Expected message/heartbeat frequency: periodic module transmit (typically 5–50 Hz depending on signal); scan tool should show live messages from CVRTD when communication is healthy
Module supply voltage: battery nominal ~12V with ignition ON; ground continuity to chassis

Diagnostic algorithm

Use a factory-level or bi-directional scan tool to read P1611 and all other present codes from all modules. Note time stamps and occurrences.
Verify battery and charging system health. Low voltage can cause modules to drop off the bus. Recharge or replace battery if needed.
Check fuses and power/ground at the CVRTD module. Back-probe or measure at connector pins for proper battery voltage with ignition ON and for a good ground.
Visually inspect the CVRTD connector and harness for corrosion, bent pins, water intrusion, or physical damage. Repair or clean connectors as needed.
With key ON (engine off), use a scan tool to monitor network data. Confirm whether CVRTD messages are present. If no messages, perform a wiggle test on harness while watching for message reappearance/intermittence.
Measure physical-layer signals with a DVOM or oscilloscope at the CVRTD data pins: confirm CAN_H/CAN_L idle voltages and check for noise, shorts to battery/ground, or missing differential signal. Verify bus termination resistance ~60 ohms.
Isolate wiring: disconnect other modules or short-into known-good bus segments only as directed by service manual. Repair any short or open circuits found in wiring or splice points.
If wiring and bus are good and power/ground OK, attempt to reflash or reconfigure the CVRTD module per service procedures. Clear codes and retest.
If the module still does not communicate after correct wiring, power and software verification, consider replacing the CVRTD module and reprogram/couple it according to manufacturer procedures.
After repair, clear codes, perform network relearn if required, and verify normal operation over a road test.
Note: Use manufacturer wiring diagrams and pinouts. Some steps require scope and factory diagnostic procedures.

Likely causes

Blown fuse or poor power/ground to the CVRTD module
Corroded or loose connector at the module
Wiring damage (pinched, chafed, or crushed) on the data bus circuit
Failed CVRTD module

Fault status

⚠️ Status

Lost serial communication with CVRTD module (CVRTD not detected on data bus).

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0-3.0 hours

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P1611 — Loss Of CVRTD Serial Data