A 2005 Jetta recently returned to the shop with recurring tail light problems after a previous repair for a faulty left rear turn signal bulb. The initial diagnosis, performed five months prior, utilizing VCDS (Vag-Com Diagnostic System) version 14.8.0.0, revealed a fault code 01501 – Bulb for Blinkers; Rear Left (M6), indicating an electrical fault in the circuit. The control module registered the signal as being sent, but the bulb remained unlit. Faulty crimp butt connectors were found and replaced at the tail light. The original autoscan also showed multiple misfires, leading to a timing chain replacement. The vehicle’s transmission control module identified as 09G 927 750 AS.
A subsequent autoscan with VCDS version 15.2.0.0, conducted upon the car’s return, revealed new issues primarily centered around various bulb malfunctions, including brake light switch implausibility (00526) and inoperative tail lights. Interestingly, the engine misfire codes were resolved after the timing chain replacement.
A significant discovery was that the original Central Electronics Control Module (CECM) coding was configured for numerous non-existent features on the vehicle. Due to the length of the long coding string, utilizing the original coding was not feasible. Attempts were made to recode the new CECM, believed to be an updated version, using the following coding:
10048E000000003200000000000000000040FF0F5C00C000000000000000While this coding partially resolved some issues, the tail lights remain inoperative, and the brake lights only function on the inner half of the light cluster. The customer also reports a brake light switch fault, although the brake lights are partially functional.
The challenge lies in finding the correct CECM coding for this specific 2005 Jetta with the 09G 927 750 AS transmission code. Incorrect coding can lead to various electrical malfunctions, as seen in this case. Further diagnosis and investigation are needed to pinpoint the root cause of the remaining tail light and brake light issues. Potential causes could include wiring harness damage, faulty grounding, or an incompatibility with the replacement CECM.
Seeking community input and expert advice is crucial for resolving this complex electrical issue. Sharing experiences with similar coding challenges on 2005 Jettas, particularly those equipped with the 09G 927 750 AS transmission, could provide valuable insights and solutions. Understanding the specific byte configurations within the long coding string and their corresponding functions is paramount to achieving proper functionality.
