Passat 2012 2.0 diesel electrics problem.

Old codger

My daughter recently bought a VW Passat 2.0 diesel saloon. It ran well for about two weeks, but then without warning all dash warnings lit up and she managed to limp home, just. It was pouring down rain for two days before it gave trouble, but no big floods and the rain may not have been a factor.The new battery was flat, I charged it and it started but indicators and wipers wouldn’t operate. I put it back on charge and after a day everything worked, then although it drove ok the dash was blank and the Rev clock and the Speedo didn’t read anything. We suspected the clocks and micro processor or/and printed circuit board in clock unit, and we got a set of clocks ( identical part numbers etc ) but still the same. We checked all the fuses and they are good and live for power. Volt meter shows 12.9 V. Any ideas out there, or anyone with experience of similar ? We are getting desperate after three weeks of trying to find a fix. Having parted with all her available cash it cannot be allowed to have too much more spent on it. If there is no easy fix it might have to be sold for parts and a big hit on her purse.

Truckermal

Have you considered taking it to a decent mechanic or VW specialist as opposed to buying random parts for it?

Did you do a scan looking for stored faults?

Old codger

Truckermal wrote: »

Have you considered taking it to a decent mechanic or VW specialist as opposed to buying random parts for it?

Did you do a scan looking for stored faults?

We took it to a favourite mechanic who has had it for four weeks now. He scanned it and got no good leads to it, he suggested a new set of clocks but they didn’t fix it. There is a car electronics specialist looking at it now but up to today it is still not sorted. Apparently a previous owner messed with the electrics . Because of lockdown we are handicapped as regards travelling out of our remote area to take it farther. Thanks for your comment.

Truckermal

If your Daughter is working then taking it to a specialist is no problem. Where are you based? That mechanic is a waste of time....

tikkamark

Hardly just the alternator after packing it in??It should be showing a lot higher than 12.9v if you took the reading from the battery terminals as the engine was running.I seriously doubt new clocks were going to sort it!

Truckermal

tikkamark wrote: »

Hardly just the alternator after packing it in??It should be showing a lot higher than 12.9v if you took the reading from the battery terminals as the engine was running.I seriously doubt new clocks were going to sort it!

Thought that or a dodgy Battery either!

Old codger

I have to defend our mechanic. As a retired machinery mechanic myself I know him to be brilliant and totally honest over many years, but electronics on today’s cars are a very specialised trade and need the attention of people who have test gear and access to the circuit diagrams of particular makes and models. I live in the extreme south west where the nearest motor electrician is in Cork.
Trial and error is not so bad for me as I can buy used parts such as alternator and clock assembly for a fraction of dealers prices and, more importantly, get a full refund if returned to breakers within one week, try that with a VW main dealer.

jimgoose

I don't know much about Volkswagen Passats, but I can tell you that a Jaguar basically turns into Borley Rectory when the alternator/battery voltage goes out of kilter. Check that alternator.

Old codger

My guy found the problem at 11.30 last night, corrosion on a module in the left front wing. Everything back working again after cleaning and remaking of contacts. A nightmare to pin down the cause, but he has correctly diagnosed so many tricky faults that others couldn’t, I felt he wasn’t going to let this one best him. The fierce two days of rain that we had directly before everything went blank may have finished the corrosion of the module. God be with the days of SIMPLE cars like the 105E Anglia and the Morris Minor. Thanks everyone who tried to help.

CoBo55

If he still has it get him to check underneath the carpet in the passenger footwell, another control unit lives there and it gets absolutely saturated. Also check there's no water gathering around the battery another famous Passat lake generator...