Last week my car had a new water pump and cam belt fitted. At the same time a 12S caravan socket was added.

 

The car previously had had a 12N socket with dedicated wiring fitted. This worked perfectly with no issues.

 

The 12S socket seems to work properly.

 

Since this work was done the rear wiper no longer works (although the washer does squirt water onto the screen). Every time the car is driven the "Error: Start-Stop system" message appears on the screen. The start-stop system worked perfectly before the work was carried out.

 

The mechanic is now on holiday for two weeks - and suggestions as to what the issue is likely to be and possible solutions?

 

The fuse for the rear wiper is fine.

Sounds like the mechanic could have made some incorrect coding changes.

 

I think you're going to need a fault code scan with VCDS or OBDeleven to understand what's been done.

Thanks PetrolDave.

 

Before starting work he said nothing would need coding as the 12S socket only required a live and two switched lives.

 

Having just connected up and tested the reverse light, something else dodgy seems to be going on. When the car is out into reverse with the caravan connected the caravan reverse light pulses a couple of times and then goes out. At the same time the car's left hand reverse light goes out too and the error message in the car tells me the LH reverse light is out.

 

Disconnecting the caravan restores the cars reverse light.

He's definitely messed things up!!! I would definitely find someone local who can do a fault code scan as it seems unlikely all the symptoms you describe aren't leaving some fault codes in their wake!

Your wiper issues may be related to trapped wiring. My Mk1 Octavia had washer & wiper issues caused by a timing belt change.

An idiot had trapped the wiring under the engine mount causing a short. 

I suggest you move your washer fluid reservoir to look for trapped wiring.

I may be totally wrong however I suggest it is worth a lot.

More to report on this.

 

I contacted a VAG group specialist today. He was totally booked up and suggested I contacted the original mechanic and gave him opportunity to put things right. I messaged him - he said that the timing was locked when he did the cam belt so it shouldn't be wrong, but that he'd strip it down and recheck and adjust the timing if necessary.

 

He then said that the rear wiper issue will be a loose connection as he's tapped into it for the ignition feed. This rung alarm bells so I've removed the trim and found where he's connected the 12S wiring. He's connected both the red and blue cables from the 12S socket together (fridge and battery charge) and then connected these both into ignition feed he's found. The ignition feed cable he's connected to certainly isn't rated to carry the load that a caravan could pull from it.

 

I'm going to go to a tow bar specialist tomorrow to get their opinion on it and get them to correct the work. I cannot believe what I've found. He's also mangled the 12S cable elsewhere - there are exposed wires showing.

Given the quality of the work the photos demonstrate, check for the possibility of trapped wires by the engine mount and wash bottle.

It is nothing to do with accuracy of timing, it is care of workmanship.

Yes - sorry. The timing issue mentioned was because the car sounds really rough on cold start - something which wasn't the case prior to the timing belt change.

 

The guy who fitting the 12vs did the timing belt too?

2 hours ago, Blue8793841 said:

The guy who fitting the 12vs did the timing belt too?

Geeze, I hope not!

Update and resolution:

 

The timing was off - sorting that cleared up the start/stop error. Does anyone know why the timing being slightly out stopped the start/stop system from working?

 

At no point did any codes show on my OBD2 reader.

 

I removed any wiring changes that had been made and rejoined any cut wires using Wagos. The 12S socket is being done by a towbar specialist who has explained to me how it will be done (i.e. properly!).

Edited 27 August, 20241 yr by MarkCro

There are quite a few parameters that inhibit automatic idle stop/start - very likely irregular engine speed from incorrect valve timing will do it.

You are extremely lucky that your so-called mechanic didn't cause some serious damage!