What does P1601 mean on a Chevy?

P1601. Lost Communication With TCM. Applies to Aveo, Colorado, S-10, Malibu, Silverado.

What causes P1601 on a Chevy?

Open Class 2 serial data line between the ECM and the TCM Blown TCM power fuse killing module communication Corroded TCM connector from water intrusion at the transmission Failed TCM pulling the serial data bus down

How do I fix P1601 on a Chevy?

Attempt TCM communication with a Tech2 or GDS2 to confirm the loss Check TCM powers, grounds, and fuses before replacing anything Inspect the Class 2 serial data circuit for opens, shorts to ground, and shorts to voltage Disconnect modules one by one to isolate a module dragging the bus down Restore communication first, then clear and verify normal shifting returns

Code

P1601

Lost Communication With TCM

Category: Powertrain - Computer and Auxiliary Controls
Severity: Check Engine Light
Applies to: Aveo, Colorado, S-10, Malibu, Silverado
Related: No single generic twin. See OBD Codes List

What it means

P1601. Lost Communication With TCM. This Chevy-enhanced code applies to Aveo, Colorado, S-10, Malibu, Silverado.

Findings, check these first

Open Class 2 serial data line between the ECM and the TCM
Blown TCM power fuse killing module communication
Corroded TCM connector from water intrusion at the transmission
Failed TCM pulling the serial data bus down

Standard procedure

Attempt TCM communication with a Tech2 or GDS2 to confirm the loss
Check TCM powers, grounds, and fuses before replacing anything
Inspect the Class 2 serial data circuit for opens, shorts to ground, and shorts to voltage
Disconnect modules one by one to isolate a module dragging the bus down
Restore communication first, then clear and verify normal shifting returns

Look up another code

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Sources and review

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Last updated 2026-09-19.

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