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Model specific boards => Golf mk4 => Topic started by: bgbazz on 10 May 2016, 14:10

Title: Implications with disconnecting the battery.
Post by: bgbazz on 10 May 2016, 14:10

I've carried various searches and don't seem to come up with a definative answer regarding disconnecting the battery for a short while. I just want to reset the ECU and anything else it affects...I've used this method on various other vehicles of mine, with no issues at all, but not too sure about the VW.

Does anyone really know?

Title: Re: Implications with disconnecting the battery.
Post by: lemski on 10 May 2016, 14:28

When doing clutches amd stuff battery is off for aslong as it takes. Last one I did, the satnav and all came back on fine. Ecu should reset after a hour... I think.

Title: Re: Implications with disconnecting the battery.
Post by: itavaltalainen on 10 May 2016, 15:40

Won't really reset, for that use diagnostics.

Title: Re: Implications with disconnecting the battery.
Post by: bgbazz on 10 May 2016, 16:02

Thanks guys. I think I'm going to give it a try anyway.

On a short drive today I stopped once and noticed the system didn't chirp when locking the car (central locking worked fine, but no chirp). When I came back and unlocked the car, all worked fine and it chirped. Ten minutes down the road, the airbag light came on, followed 5 mins later by the message "airbag fault" on the screen. I pulled over, switched the motor off and waited a couple of minutes before restarting and driving on...same thing happened after a few minutes so I drove home and hooked up my OBD reader. Performed a scan 3 times and the result was always the same...no faults found. I used the setting to turn the light off and that worked fine...but it comes back on after 5 mins or so while driving.

Got me stumped.  :undecided:

Title: Re: Implications with disconnecting the battery.
Post by: itavaltalainen on 10 May 2016, 16:43

What reader do you have? OBD2?

Title: Re: Implications with disconnecting the battery.
Post by: bgbazz on 10 May 2016, 17:57

Yes I do, but I've just discovered that it can't read airbag faults, so I'm going to head down a different track tomorrow and see what I end up with.

Title: Re: Implications with disconnecting the battery.
Post by: lemski on 10 May 2016, 18:23

Itll more than likely be the seat connection on one of the front seats.

Title: Re: Implications with disconnecting the battery.
Post by: itavaltalainen on 10 May 2016, 18:34

Yeah get VCDS - most useful tool for VWs.

Title: Re: Implications with disconnecting the battery.
Post by: bgbazz on 10 May 2016, 20:18

Quote from: lemski on 10 May 2016, 18:23

Itll more than likely be the seat connection on one of the front seats.

Thanks mate...that is one of the things I'll be looking at in the morning.

Title: Re: Implications with disconnecting the battery.
Post by: bgbazz on 10 May 2016, 20:21

Quote from: itavaltalainen on 10 May 2016, 18:34

Yeah get VCDS - most useful tool for VWs.

You're probably right...I will see if I can find one and get it imported.

Title: Re: Implications with disconnecting the battery.
Post by: itavaltalainen on 10 May 2016, 21:03

There is a distributor in Bulgaria:

http://www.ross-tech.com/distributors.php

Title: Re: Implications with disconnecting the battery.
Post by: bgbazz on 11 May 2016, 05:57

Thanks for the link...what sort of kit should I be looking for?

Title: Re: Implications with disconnecting the battery.
Post by: bgbazz on 11 May 2016, 15:19

I had a good look at the connections under both of the seats today (hard little buggers to get close to), gave them a wriggle etc...no joy.

Also had the battery disconnected for just over an hour...still no joy.

Looks like a long trip to have the system checked and diagnosed by a specialist.    :sad:

Title: Re: Implications with disconnecting the battery.
Post by: itavaltalainen on 11 May 2016, 15:32

Ross-Tech Hex+CAN is what you want (MiniCAN does not support mk4 anymore).

Course fault is still in memory, it only deletes itself after very long time, that is assuming wiggling the cables has (temporarily) sorted it. Disconnecting the battery does squiddly squat to fault codes.

Title: Re: Implications with disconnecting the battery.
Post by: bgbazz on 11 May 2016, 17:43

Thanks for the reply.

As I said above, wiggling the cables did nothing at all, but the battery disconnect exercise, whilst not working on VW cars, DOES work on some other brands. I solved the airbag light problem on two of my Peugeots and resolved various problems on my 2003 Jeep Cherokee, Nissan Patrol and Toyota Yaris, just by disconnecting the battery for a while.
One of the best examples was the Jeep...before the battery trick, it was giving around 15 liters/100kms...afterwards, that figure dropped to around 8 liters. 6 years later and the consumption is still the same. Another one is the Yaris...CEL light was on and scanner indicated 02 sensors faulty...battery trick and 3 years down the track, the light has not returned and my scanner shows no faults.

I am not taking the p!ss, but I am having trouble getting my head around all this electrickery stuff.

I will be taking the drive tomorrow and visiting the closest Bosch service centre which has all the VAG diagnostic
equipment...fingers crossed for a solution.

Thanks again for your advice.

Title: Re: Implications with disconnecting the battery.
Post by: bgbazz on 01 June 2016, 17:44

Quote from: itavaltalainen on 10 May 2016, 21:03

There is a distributor in Bulgaria:

http://www.ross-tech.com/distributors.php

Just to update....I contacted the local distributor...they are not even remotely interested in any vehicle pre 2014.
Basically got told to feck off.

My Bosch man did a detailed scan and no faults came up...he reset the airbag warning light and after roughly 300 miles of driving, it has not returned. Just for peace of mind, I went back and had the car scanned again today...no faults or codes came up.

I would still like a scanner of my own though.

Thanks again to all who offered advice.