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Today we will share a repair case about 2012 Volkswagen Golf 6 Sedan that cannot be started. The car is equipped with CFBA direct injection engine and DSG 7speed automatic transmission, the user reported that when starting the vehicle, the instrument panel shows “put the gear selector lever in the P/N position”, but the vehicle can never start. The following is a detailed description of the troubleshooting process and repair steps.

1. Fault recognition and initial inspection

The user reported a failure to start the vehicle. We first turned on the ignition switch and tried to start the engine, but the starter did not respond at all. At the same time, the gear indicator light on the instrument panel flashed and the message “Place the gear selector lever in the P/N position” appeared. This indicates that the vehicle is not recognizing the correct gear signal under certain conditions.

2. Failure analysis and possible causes

According to the fault phenomenon, the possible causes of the fault are as follows:

  • Low battery voltage
  • Malfunction of the ignition switch
  • Fault in the starting signal circuit from the ignition switch to the central electrical control unit J519
  • Failure of the starter relay J682 or its related wiring
  • Fault in the wiring from starter terminal 50 to J682
  • Fault in starter itself
  • Abnormal P/N gear signal

3. Troubleshooting procedure

(1) Check the battery voltage

We first checked the vehicle's battery voltage, measured voltage of 12.60V, indicating that the battery power supply is normal, so the low battery voltage fault can be ruled out.

(2) Check the ignition switch signal

Next, we connected the fault diagnostic instrument and checked the data flow of 09Central Electrical Control Unit. When the ignition switch was in the start gear, the diagnostic instrument showed that terminal 50 was on, proving that the start signal line from the ignition switch to the central electrical control unit J519 was normal.

(3) Checking the P/N gear signal

We further checked the P/N gear signal data stream of the central electrical control unit. The data stream showed that when the gear was in P/N, the display showed “not engaged”, whereas under normal conditions, the display should show “engaged”. This indicates that the vehicle's gear signal is not recognized correctly, resulting in failure to start.

(4) Check the shift lever signal of the transmission control unit.

When checking the data flow of the transmission control unit in the diagnostic instrument, we found that the shift lever information was transmitted normally and the gear position information was accurately transmitted to the electromechanical unit.

(5) Checking circuit signals

According to the circuit diagram, we checked the voltage from terminal T52c/30 of the central electrical control unit J519 plug to terminal T25/16 of the transmission plug. The voltage was 11.70 V when the gears were in P/N, R, D, and S. Normally, the voltage should be 0 V only in P/N gear and 11.70 V in R/D/S gear.

4. Fault analysis

Based on the above inspection results, we conclude that at the time of the malfunction, regardless of whether the vehicle gear is in P/N or R/D/S, the voltage at terminal T52c/30 of J519 is always 11.70 V. This suggests that the central electrical control unit, J519, has misjudged that the transmission gear is in a nonP/N gear, and thus failed to activate the starter relay at terminal 50. After analysis, we determined that the source of the fault was a fault in the transmission control unit.

5. Troubleshooting and repair

Based on the fault diagnosis, we decided to replace the electromechanical unit of the automatic transmission. After replacement, we conducted a comprehensive inspection of the vehicle to ensure that the circuit and signal transmission are normal. After the repair is completed, the vehicle starts smoothly, the instrument panel display is normal, the gear signal is correctly recognized, and all faults are eliminated.

Summary

Through a detailed investigation of the 2012 Volkswagen Golf 6 Sedan Cannot Start malfunction, we found that the root cause of the problem lies in the malfunction of the transmission control unit, resulting in the central electrical control unit not being able to correctly recognize the P/N gear signal. By replacing the transmission electromechanical unit, the problem was successfully resolved. If your vehicle has a similar problem, you can refer to the above troubleshooting steps to find and fix the problem in time to ensure the normal use of your vehicle. If you need further assistance, please feel free to contact our professional repair team.

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