TCU Code 4 - Stepping Motor
- With all harnesses connected, check that continuity exists between TCU connector pins No. 8 and 13. Turbocharger stepping motor cable lever must be in relaxed position so internal micro switch is on. Now check that no continuity exists between pins No. 8 and 13 when turbocharger stepping motor cable lever is turned manually.
- If tests results in step 1) are correct, replace TCU. If either test result in step 1) is incorrect, check for continuity at stepping motor and replace harness or stepping motor. See Fig 1 .