Repairing vehicles without locking up the radio antitheft system
 

I want to start repairing cars that don't belong to me. Many car
owners are not aware that disconnecting the battery power for any
reason will lock up the radio antitheft system, so they often don't
have the code readily available. Since it is safe practice to
disconnect the battery first, how can I change common items like
sensors, alternators, starters, etc. without locking up the car owner's
sterio? How does a small garage operate? Do they register with the
dealers in some way? Anybody got any info?

Thanks,
RepairJunkie

Repairing vehicles without locking up the radio antitheft system
 

I had my car battery disconnected for a week or so. The radio did not
complain when I reattached it. Some folks use a 9 volt battery in the
cigarette lighter to keep the juice going. Of course if you let the
interiour lights on then that little battery would be useless. 2003
Jetta

On 10 Sep 2006 13:59:58 -0700, "RepairJunkie" >
wrote:

>I want to start repairing cars that don't belong to me. Many car
>owners are not aware that disconnecting the battery power for any
>reason will lock up the radio antitheft system, so they often don't
>have the code readily available. Since it is safe practice to
>disconnect the battery first, how can I change common items like
>sensors, alternators, starters, etc. without locking up the car owner's
>sterio? How does a small garage operate? Do they register with the
>dealers in some way? Anybody got any info?
>
>Thanks,
>RepairJunkie

Repairing vehicles without locking up the radio antitheft system
 

Jim Behning wrote:
> I had my car battery disconnected for a week or so. The radio did not
> complain when I reattached it. Some folks use a 9 volt battery in the
> cigarette lighter to keep the juice going. Of course if you let the
> interiour lights on then that little battery would be useless. 2003
> Jetta
>
> On 10 Sep 2006 13:59:58 -0700, "RepairJunkie" >
> wrote:
>
> >I want to start repairing cars that don't belong to me. Many car
> >owners are not aware that disconnecting the battery power for any
> >reason will lock up the radio antitheft system, so they often don't
> >have the code readily available. Since it is safe practice to
> >disconnect the battery first, how can I change common items like
> >sensors, alternators, starters, etc. without locking up the car owner's
> >sterio? How does a small garage operate? Do they register with the
> >dealers in some way? Anybody got any info?
> >
> >Thanks,
> >RepairJunkie

Most manuals state that power should be disconnected before
plugging/unplugging sensors. Is this a common practice for small
garages? Do they use a 9V battery in the cigarette lighter?

Repairing vehicles without locking up the radio antitheft system
 

I had a battery changed at the Advanced Auto parts and they have a full
sized car battery that plugged into the cigarette lighter. Said they are
required to do it on all newer cars to prevent ECU failures.

Cecil

"RepairJunkie" > wrote in message
ps.com...
>
> Jim Behning wrote:
> > I had my car battery disconnected for a week or so. The radio did not
> > complain when I reattached it. Some folks use a 9 volt battery in the
> > cigarette lighter to keep the juice going. Of course if you let the
> > interiour lights on then that little battery would be useless. 2003
> > Jetta
> >
> > On 10 Sep 2006 13:59:58 -0700, "RepairJunkie" >
> > wrote:
> >
> > >I want to start repairing cars that don't belong to me. Many car
> > >owners are not aware that disconnecting the battery power for any
> > >reason will lock up the radio antitheft system, so they often don't
> > >have the code readily available. Since it is safe practice to
> > >disconnect the battery first, how can I change common items like
> > >sensors, alternators, starters, etc. without locking up the car owner's
> > >sterio? How does a small garage operate? Do they register with the
> > >dealers in some way? Anybody got any info?
> > >
> > >Thanks,
> > >RepairJunkie
>
> Most manuals state that power should be disconnected before
> plugging/unplugging sensors. Is this a common practice for small
> garages? Do they use a 9V battery in the cigarette lighter?
>

Repairing vehicles without locking up the radio antitheft system
 

Starting around late 1999 or early 2000 the VW radios pick the code from the
cluster. That if the radio was never replaced!

"Jim Behning" > wrote in message
...
>I had my car battery disconnected for a week or so. The radio did not
> complain when I reattached it. Some folks use a 9 volt battery in the
> cigarette lighter to keep the juice going. Of course if you let the
> interiour lights on then that little battery would be useless. 2003
> Jetta
>
> On 10 Sep 2006 13:59:58 -0700, "RepairJunkie" >
> wrote:
>
>>I want to start repairing cars that don't belong to me. Many car
>>owners are not aware that disconnecting the battery power for any
>>reason will lock up the radio antitheft system, so they often don't
>>have the code readily available. Since it is safe practice to
>>disconnect the battery first, how can I change common items like
>>sensors, alternators, starters, etc. without locking up the car owner's
>>sterio? How does a small garage operate? Do they register with the
>>dealers in some way? Anybody got any info?
>>
>>Thanks,
>>RepairJunkie

Repairing vehicles without locking up the radio antitheft system
 

This all makes sense for changing the battery, but not for the starter
or alternator because you can easily cause shorts and definitely not
for sensors because plugging/unplugging when they are getting powered
thru the cigarette lighter can damage the computer. It depends on
whether the computer's sensor amplifier (an In-Amp) is overload
protected. I am speaking from the perspective of an electrical
engineer, but someone much more familiar with common practices in the
auto industry can probably tell me what's really going on. In any case
I'll speak with Advanced Auto. Thanks!

Repairing vehicles without locking up the radio antitheft system
 

RepairJunkie wrote:
> This all makes sense for changing the battery, but not for the starter
> or alternator because you can easily cause shorts and definitely not
> for sensors because plugging/unplugging when they are getting powered
> thru the cigarette lighter can damage the computer. It depends on
> whether the computer's sensor amplifier (an In-Amp) is overload
> protected. I am speaking from the perspective of an electrical
> engineer, but someone much more familiar with common practices in the
> auto industry can probably tell me what's really going on. In any case
> I'll speak with Advanced Auto. Thanks!

Unless -- with the key in the accessory position -- the radio and
cig.lighter are energized and the ECU (computer) are disconnected from
the circuit. This would keep power to the radio, but removing the
(underhood) battery would cut power to the ECU, thus allowing sensors,
alternator, starter, etc. to be plugged/unplugged safely. Anybody know
if this is true and where I can find a tech. write-up on it?

Repairing vehicles without locking up the radio antitheft system
 

I had my battery changed twice in 3 years on my 1999 Passat with no external
power connected to the car
VW cars compare the code on the wireless with the remembered wireless code
stored in it's control unit
if it's the same then no problem, if the wireless is replaced then you need
the code for that wireless.

"Lost In Space/Woodchuck" > wrote in message
...
> Starting around late 1999 or early 2000 the VW radios pick the code from
> the cluster. That if the radio was never replaced!
>
> "Jim Behning" > wrote in
> message ...
>>I had my car battery disconnected for a week or so. The radio did not
>> complain when I reattached it. Some folks use a 9 volt battery in the
>> cigarette lighter to keep the juice going. Of course if you let the
>> interiour lights on then that little battery would be useless. 2003
>> Jetta
>>
>> On 10 Sep 2006 13:59:58 -0700, "RepairJunkie" >
>> wrote:
>>
>>>I want to start repairing cars that don't belong to me. Many car
>>>owners are not aware that disconnecting the battery power for any
>>>reason will lock up the radio antitheft system, so they often don't
>>>have the code readily available. Since it is safe practice to
>>>disconnect the battery first, how can I change common items like
>>>sensors, alternators, starters, etc. without locking up the car owner's
>>>sterio? How does a small garage operate? Do they register with the
>>>dealers in some way? Anybody got any info?
>>>
>>>Thanks,
>>>RepairJunkie
>
>

Repairing vehicles without locking up the radio antitheft system
 

Thanks so much! Finally found it. Do a Google search on " auto memory
saver" and it comes up all over the place.

Thanks to all who helped!

Repairing vehicles without locking up the radio antitheft system
 

Thanks so much! Finally found it. Do a Google search on " auto memory
saver" and it comes up all over the place.

Thanks to all who helped!