OBD2 ECU Memory Saver

[Jim GM4DHJ ...]

anybody use one of these ?...are they safe?

[Dave Liquorice]

Donno, I just made up a open end to lighter plug made sure the lighter socket was powered and connected a 12 V SLA to the open ends. With a modern car one might have to be quick changing the main battery as they have a habit of going to sleep after a while and might switch off the lighter socket...

I guess the ODBII power line is less likely to be turned off. Or find other unswitced/secure +V and Gnd points, obvoious place is the around the battery terminals but there is a chnace that one connection might get dislodged whilst faffing about with the battery...

[alan_m]

Yes you definitely need one. If you remove the battery your car's computer will delete all its programming and you will never be able to start your car again without getting it back to the main dealer for a repair costing maybe £1000!

You are now powering your whole car through those two little pins on the OBD connector. You will possible do more than £5 in damage if it draws too much current.

[Smolley]

My car started and ran ok after removing the battery for a couple of weeks, must have non volatile memory in the ECU. .

[Fredxx]

Please name the car that does this. All that I have come across work perfectly well after removing the battery. The major pain is resetting the radio etc.

That depends on the wiring, but while that may be a concern, the current draw with everything turned off would normally be measured in mA.

If you believe otherwise provide the evidence.

[The Natural Philosopher]

Only thing my old freelander needed was radio recoding

Only time I have heard of a car failing to go after a battery disconnection is when a major sensor array has been replaced as part of a service. Some parts are manufacturer specific unless you know the magic.

[Dave Plowman (News)]

Quite. Never had a car that was worried about being powered down totally. Except for losing relatively unimportant things like the radio station memory.

If it does get rid and buy a properly designed one.

[charles]

my car started perfectly after having had teH battery disconn3cted for 6+ weeks. It's what the manual tells you todo.

[alan_m]

Woosh

No car does that's why you don't this piece of crap.

All it does is apply whatever voltage you connect the leads to into the power pins of the OBD socket to supply the ECU, and the rest of the car. Its effectivly just two pieces of wire!

If when removing the car's battery you accidentally short the +ve battery lead to the chassis you will short circuit the supply you have just connected to the OBD socket. I wonder what current will then flow?down the car's internal wiring?

[alan_m]

But nothing that important. It may run rougher for 10 to 15 minutes but I guess most people wouldn't notice.

Go and find a Youtube video to show that these things work :) One shows that after connecting one of these devices, then disconnecting and re-connecting the car's battery all the engine sensors are still connected to the ECU and still working !!!!

[Dave Plowman (News)]

What would that be, Jim? It may revert to ignition timing for low octane fuel, until the knock sensors tell it otherwise. An auto gearbox might learn how you normally drive to some extent. But all that sort of thing would update very quickly.

[Fredxx]

So remind us, what idiot said, "If you remove the battery your car's computer will delete all its programming and you will never be able to start your car again without getting it back to the main dealer for a repair costing maybe £1000!" and now they can't provide the evidence to backup their silly claim up.

Then tell us, what will limit the current?

[Dave Liquorice]

Yes but if one of the temporary wires connecting that falls off with the main battery disconnected...

I think the reason I did it was partly proof of concept but mainly because didn't know the radio code. The Disco II would take about 100 miles to "re-learn" the engine and my driving style. Freelander II is much quicker, barely noticeable unless you want a quick take off within the first few miles when it won't have quite the normal amount of GO!