Powertrain, generic · Computer and auxiliary outputs

P0649 Speed Control Lamp Control Circuit

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modeNo

The engine module switches this hard-wired output with its own driver and checks the circuit electrically (open, short to ground or voltage) – it cannot see whether the lamp lights; on CAN-based cars such faults appear as U codes. P0649 concerns the cruise control ('speed control') indicator where the engine module drives it by wire. No manufacturer document available to us uses this code; the description follows CARB and the component. CARB names cruise control as an example of a function outside the test cycles, and GM rates its cruise control diagnostics as emission neutral without the check engine light. The indicator then does not work or stays on; whether cruise control is also disabled depends on the maker. Cruise control inputs and switches have their own codes (P0564–P0581).

Likely causes

Wire or connector between module and receiver open, corroded or shorted
Bulb/LED or instrument cluster faulty
Instrument cluster faulty
Output driver in the module faulty

Symptoms

  • Cruise control indicator not working or stays on
  • Cruise control possibly disabled (depending on the maker)
  • Code stored

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€50–400
Time0.5–2 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

cruise control lampinstrument clusterlamp control circuit

Related codes

P0575P0565P0567P0571P0650

References: law.cornell.edu, gsi.ext.gm.com.