Reset by disconnecting the battery - HOW?

Following is an instruction for 'ECU Reset' that I found in another forum:

Turn off the ignition.

Now, disconnect the negative terminal of the battery and then hold the negative cable against the 'vehicle ground' (so that all the current from the entire system can flow through the ground).

That's something you should do for about 15 to 20 minutes, that's how long it takes!

Then reconnect the negative cable to the battery... –done-!

We have also done similar 'resets' before, but without holding the cable to ground – and it worked.

Now I'm wondering, of course, why one should hold the negative cable against the ground – but it's already connected to ground, isn't it?

Now I'm wondering, of course, why one should hold the negative cable against ground – but it's already connected to ground, isn't it?

Yeah, the whole thing about faith and the mountains, you know...

Reset simply means disconnecting the cable from the battery. 'A reduction in mass is nonsensical, as it is already installed from the factory (mass band).'

Can I ask where the instructions came from? Motortalk, Octi-Forum, GuteFahrt?

Hi,

Since the TDI control unit completely disconnects from the power supply using the well-known relay 109, the purpose of such actions is highly questionable.

I find the "complete discharge" concept brilliant; I haven't read anything this amusing in a long time. Does the person who came up with this idea actually know the difference between water and electrical current? And has he ever checked where the other end of the ground wire is connected?

Best regards,

Jan

Reset works because the cable is disconnected from the battery. 'A reduction in mass is nonsensical, as it is already installed from the factory (mass band).'

Exactly, that's how I see it too - which is why I'm asking.



Can I ask where the instructions came from? Motortalk, Octi-Forum, GuteFahrt?

While it originates from a BMW forum, the principle (negative wire to ground) is the same as what they use there.

http://www.bmwforum.de/showthread.php?s=&threadid=2841

Not again...

Hi,

I recently read the original article in the BMW forum... and once again, I was able to confirm something interesting:

Such "expert contributions" are typically characterized by the fact that the author,

- a preference for using the exclamation mark, even when it's not appropriate
- often uses more than one exclamation mark in a row
- doesn't know that one shouldn't put a space before punctuation marks

Best regards,

Jan

Not again...

Sorry, if such a thread already existed and I missed it.

But somehow, this claim left me
'and then connect the negative cable to 'vehicle ground'
no peace - that's why I'm starting this thread here.

Hello Martin,

Some time ago, we had already considered this to be an endless story. Most engine control units are already without power when the ignition is off. There's no way to go any further, so what else can you disconnect? There might still be some exceptions.
-> Search function (Uwe Ross had written something about it).

Hello, Rainer

1. Almost no MSTG remains completely without power after the ignition is switched off. For example, a 130hp TDI can still receive information about oil temperature, etc., for up to 1 hour after being turned off.

It's not quite the same without the reset. I once had a customer who had installed an alarm system that would lock the doors when the ignition was turned on.

the car was running, engine turned off, ignition re-started and door closed ----> car is on and key inside!
he then retrieved the spare key, unlocked the car, but it wouldn't start, there was no starter, no ignition, and it wasn't a problem with the WFS or relay 219...

battery for 15min, reset all STG, and then it turned on immediately on the first try!




bye bye

yes, sometimes a reset can work wonders.
At BMW, for example. ABS, Airbag, Combination, BME, Radio, etc. Due to the software malfunctioning.

However, in my experience with VAG vehicles, it hasn't really done anything except once, when the radio started working again afterward

Basti wrote:

1. Almost no MSTG remains running after the ignition is switched off; it remains essentially without power, while a 130hp TDI with ZBSP can still receive information about oil temperature, etc., for up to 1 hour after being switched off.

Hi,

As far as I know, the ASZ engine control unit completely loses power a few seconds after the engine is turned off, via the 109 system.
It doesn't have a continuous plus connection (if the circuit is identical to the ATD and AXR in that respect - I haven't yet obtained the ASZ plan . . .).

It might be the case that CAN data such as oil temperature is still available via the KI - but what should the engine control unit (ECU) do with this information if it is without power

1. Almost no MSTG remains running after the ignition is switched off; it remains essentially without power, while a 130hp TDI with ZBSP can still receive information about oil temperature, etc., for up to 1 hour after being switched off.


That would really surprise me, because the oil temperature sensor is supplied by terminal 15. The 'afterrun' in the ASZ should be finished no later than 15 seconds.
From this point on, the EDC is completely power-free, and since it doesn't store any data in RAM disconnecting it will not help in any way...
If the EDC is integrated into the fan or water pump control, it is then possible to apply the afterrun in such a way that the EDC ensures cooling of the engine after it has been turned off.

-- alarm system --

This could also be the case with the alarm system. Because, besides the airbag, all other control units in the TDI are connected to a permanent power supply (including the automatic transmission).
DA, disconnecting then may sometimes help with the reset.
but NOT at EDC.

See you, Gremlin