Chrysler 77 Speed Control Relay Circuit
How to read it
Code 77 reads as 7 flashes, pause, 7 flashes on the check-engine light. Cycle the ignition key on, off, on, off, then leave it on with the engine off, and count the flashes on the power loss or check-engine light.
New to flash codes? The How to Read Chrysler OBD-I Codes with the Key Cycle walks through the test and what the numbers mean. The general OBD-I guide covers the rest.
What does Chrysler code 77 mean?
Speed Control Relay Circuit
Common causes of 77
- Failed speed control power relay
- Open or shorted relay wiring to the controller
- Failed speed control servo
- Faulty relay driver in the controller
How to fix 77
- Confirm the speed control engages on a road test
- Swap the speed control relay with an identical one and retest
- Test the relay coil resistance and check it clicks with power
- Inspect the relay wiring and servo connector for damage
- Replace the failed relay or servo
- Clear the code and verify cruise control operates
Sources and review
Review: qualified. Read the source limits below.
- Chrysler OBD-I trouble codes, model and year page
live reference page (troublecodes.net)
Supports: code identity and Chrysler meaning
Fetched directly from the linked model page. Single publisher, so the record is qualified, not verified. Causes and check order are curator-written from the circuit the code names.
- Chrysler OBD-I trouble codes, model and year page
live reference page (troublecodes.net)
Supports: code identity and Chrysler meaning
Fetched directly from the linked model page. Single publisher, so the record is qualified, not verified. Causes and check order are curator-written from the circuit the code names.
Last updated 2026-10-10.
Report a correction for 77. Include your vehicle, the issue and a source if you have one.