What causes GM code 47?

Open serial data line between modules Failed body or climate module pulling the line down Corroded ALDL connector data pin Poor module ground shared with the data circuit

How do I fix GM code 47?

Check whether other modules still communicate through the ALDL port Inspect the data line wiring for opens and shorts Disconnect add on modules one at a time and recheck communication Verify module powers and grounds before replacing a module Clear the code and confirm data exchange resumes on a scan tool

47 UART Serial Data Circuit Error

Q: What does GM code 47 mean?

GM code 47 — UART Serial Data Circuit Error. Applies to 1988-1995 GM cars with electronic climate or trip computers.

Make: GM (1982-1995)
Category: Powertrain - Computer and Auxiliary Controls
Severity: Check Engine Light
Applies to: 1988-1995 GM cars with electronic climate or trip computers

How to read it

Code 47 reads as 4 flashes, pause, 7 flashes on the check-engine light. Jump terminals A and B on the ALDL connector with the key off, then turn the key on with the engine off and count the check-engine flashes.

What does GM code 47 mean?

47 — UART Serial Data Circuit Error. This code sets when your vehicle computer detects uart serial data circuit error.

Common causes of 47

Open serial data line between modules
Failed body or climate module pulling the line down
Corroded ALDL connector data pin
Poor module ground shared with the data circuit

How to fix 47

Check whether other modules still communicate through the ALDL port
Inspect the data line wiring for opens and shorts
Disconnect add on modules one at a time and recheck communication
Verify module powers and grounds before replacing a module
Clear the code and confirm data exchange resumes on a scan tool