GM 38 TCC Brake Switch Circuit Error
How to read it
Code 38 reads as 3 flashes, pause, 8 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.
New to flash codes? The How to Read GM OBD-I Codes with a Paperclip walks through the test and what the numbers mean. The general OBD-I guide covers the rest.
What does GM code 38 mean?
TCC Brake Switch Circuit Error
Common causes of 38
- Brake switch stuck in one position
- Shorted wiring between the brake switch and ECM
- Failed TCC solenoid confusing diagnosis on some models
- Corroded ECM connector pin for the brake input
How to fix 38
- Test brake switch continuity in both pedal positions
- Check that TCC applies in overdrive and releases with light braking
- Inspect wiring for shorts to ground or power
- Test the TCC solenoid circuit if the brake input tests good
- Clear codes and confirm normal lockup behavior on a road test
Source
Qualified source review
Sources and review
Review: qualified. Read the source limits below.
- GM and Chevrolet OBD1 Trouble Codes (ALDL Fault Code List)
live reference page (troublecodes.net)
Supports: code identity and GM meaning
Fetched directly. Single publisher, so the record is qualified, not verified. Causes and check order are curator-written from the circuit the code names.
https://www.troublecodes.net/gm/
Last updated 2026-09-19.
Report a correction for 38. Include your vehicle, the issue and a source if you have one.