Ignition Signal (Code 21)
- Disconnect 20-pin connector and check for continuity between terminals 3, 5 and ground.
- If there is continuity, check power transistor. With ohmmeter positive lead on terminal 1, continuity should be found at terminals 3 and 2. With positive lead at terminal 2, continuity should be found at terminal 3. See Fig 1 . If okay, replace control unit.