GM 80 Transmission Component Slipping
How to read it
Code 80 reads as 8 flashes, pause, 0 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 80 mean?
Transmission Component Slipping
Common causes of 80
- Low trans fluid level
- Worn clutch packs or band
- Failed shift solenoid
- Faulty input or output speed signal
How to fix 80
- Read codes with an ALDL scan tool
- Check fluid level and condition right away
- Road test and note which gear slips
- Test shift solenoids and wiring
- Check line pressure if gauges are available
- Rebuild or replace internal parts if slip is confirmed and fluid is full
Source
Qualified source review
Sources and review
Review: qualified. Read the source limits below.
- GM OBD1 trouble codes, model and year page
live reference page (troublecodes.net)
Supports: code identity and GM meaning
Fetched directly from the linked model page. Single publisher, so the record is qualified, not verified.
https://www.troublecodes.net/GM/91_49B/
Last updated 2026-09-19.
Report a correction for 80. Include your vehicle, the issue and a source if you have one.