Hi Guys

Apologise for such a long post but I really need your help! My wife has several hospital appointments due to some pregnancy complications and I need to sort out the car ASAP.

I own 300c 3.0 CRD 2006 LX.

Current state:

• Car dashboard says “service park assist”
• Transmission shifter stuck in ‘park’ however I can move to ‘D’ when pushing the secret pink button on the side. There is a speed limit with only 1st gear working.

History:

One day I went to the local gas station. After top-up, and 5min of calm driving suddenly most of the dashboard lights turned on like a christmas tree + service park assist + the charging voltage was around 17Volts. So I pulled to the side immediately and called for recovery to the local garage.


Symptoms then:

When pushing the gas pedal the voltage was going up above 17-18V until the whole dashboard backlight went off. The backlight was coming back on when releasing the gas pedal while the voltage remained around 16-17V.


Repairs done to date:

At the garage, the mechanic disconnected the battery while the car was running and the tested voltage on clamps - was 20.2 Volts. There were signs of oil on the alternator so he replaced it and charged £580. When I came to collect the car thinking all is sorted I couldn’t drive off because the shifter was stuck in park - this issue wasn’t there when I left the car at the garage before! When I was leaving the car, the gearbox was working except the excessive voltage in the system. When I raised the issue with the mechanic upon collection, he started being rude and aggressive saying it is not his fault, he just changed the alternator and that’s it. After a quick research, he said it might be the solenoid, but he cannot get the part so I need to take the car, because it is not safe at his place. He can replace the solenoid for free once I’ve got the part.


I took the car home, checked visually all the fuses in the front and back and found only 1 burnt, but the car shifter is still blocked.


I’m not planning to go back to that mug head mechanic anymore due to the way he treated me therefore can someone please direct me?


after watching this video:

You Tube

it seems it is not the 'pink thingy' issue, but rather shifter solenoid - am I correct? When I’m pushing the brake pedal I cannot hear any ‘clicking’ noise. Where can I find that solenoid? What is part No.?


What else I could sort out myself? When looking at the active error codes… Is my car totally messed up now?

 

How old is the battery and what condition is it in? A weak/failing battery will mess with the computers and electronics and cause all sorts of weird behavior and seemingly random dtc's. The battery voltage with the motor off for at least 20 minutes should be at least 12.4 volts, minimally 12,2 and never below 12.0 volts.

The charging voltage is extremely high; should be around 14.4-14.6 volts. How were you measuring the voltage to see 17-18 volts? For a charging voltage that high, I would suspect possible corrosion somewhere in the charging system wiring, a possible bad/missing ground or even corrosion at the battery terminals.

It is not recommended to disconnect the battery on a running vehicle; the voltage surge can adversely affect the computer modules. The battery is needed to smooth out any voltage spikes and stabilize the system voltage.

I agree with you on not taking your car back to that mechanic, Oil on the alternator may simply be a drip off of the dipstick when checking the oil (I know this for a fact). It may be the alternator was failing but oil on is not an indication.

 

Hi ggoose, thanks for the reply.
The battery is 2 months old. I took it out for the night and charged. The mechanic left it at approx 20%. With motor OFF I have 12.4V on the EVIC dashboard. When driving with lights ON and AC on full output it keeps steady 14.6V.

I keep the voltage preview on the EVIC dashboard all the time as per the screenshot. Now, with the replaced alternator the voltage is steady as mentioned above, but the shifter is still locked unless I push the side button with the only 1st gear working.

 

Did you fixed and what was it please share

 

3 mechanics / car electricians couldn't figure this out so I started reading the full car manual myself. The troubleshooter indicated I need to replace the whole transmission shifter. I found a used one on ebay making sure the part No. is the same, ordered, replaced and the car is alive since

The overvoltage must have burnt something on the PCB controller within the shifter assembly and the car lost communication to it. It is likely that the bloody mechnic short circuited the system while showing me "the battery is good" and making some sparks when all was connected. He was a proper dumbass.