Battery Changeout-Computer Memory Saver

TheKid7

Well-known member
Joined
Oct 15, 2007
Location
Corpus Christi, TX
TDI
2003 Jetta TDI Sedan
I am planning to change out my battery myself on my 2003 Jetta TDI in the near future. The changeout is going to be done for preventative maintenance (before the battery fails). I do not want to be stranded somewhere. I did not know until today that you need to keep voltage on the computer during the changeout process. I have located an inexpensive 9 volt computer memory saver that I can purchase.

Questions:

1. What happens to the computer if power is totally lost? Will the car not start at all with the new battery?

2. How many other makes/models of vehicles require a computer memory saver hookup for a battery changeout? I never had any known problems with my battery changeouts of my previous vehicles (1993 Mercury Sable & 1995 Chevrolet P/U).

Thanks in Advance.
 

Vince Waldon

Top Post Dawg
Joined
Apr 25, 2009
Location
Edmonton AB Canada
TDI
2001 ALH Jetta, 2003 ALH Wagon, 2005 BEW Wagon
I think you've been misinformed. Unless you are worried about losing your radio presets and clock time there's no reason to maintain battery voltage... the car and ECU will be fine. Kinda makes sense...how long would a car design last where the car was toast if you ever left your headlights on?!

For safety sake it's a good idea on any car equipped with airbags to make sure there's no one in the car when you reconnect the battery, and you may need run the power windows up and down a couple of times to initialize the controller module, but other than that swap away.
 
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jettawreck

Top Post Dawg
Joined
Aug 2, 2004
Location
Northern Minnesota-55744
TDI
2001 Jetta and 2003 Jetta
Vince Waldon said:
I think you've been misinformed. Unless you are worried about losing your radio presets and clock time there's no reason to maintain battery voltage... the car and ECU will be fine. Kinda makes sense...how long would a car design last where the car was toast if you ever left your headlights on?!

For safety sake it's a good idea on any car equipped with airbags to make sure there's no one in the car when you reconnect the battery, and you may need run the power windows up and down a couple of times to initialize the controller module, but other than that swap away.
X2 as above. You have been BS'ed.
The only other thing I would add is to be very careful not to let the battery cables touch/ground out to anything and place them onto the respective PROPER connectors (+/-) correctly and firmly. Don't just lay them there until you tighten them up. I have found out (the hard way) that the radio/stereo head unit can be rather sensitive to this sort of thing. :eek:
The only thing lost the last couple times I've changed batteries was the clock time, radio presets and antitheft recovered themselves.
 

CFIMuncie

Active member
Joined
Sep 30, 2011
Location
Ridgeway, VA
TDI
2000 Jetta
Just want to confirm that you do not need a memory saver. The repair manual that I have states that you will have problems if you do not use a memory saver. Says that you will have to have a scan tool to reset several values in the ECM if you do not use a memory saver. I have a 2000 TDI Jetta that needs some stater work and I would rather not weld my wrench to the frame.
 

JB05

Top Post Dawg
Joined
Oct 20, 2005
Location
Il.USA
TDI
Golf,2005,anthracite blue
All you may need to worry about is the radio code which should be in the owner's manual. You will have to reset the clock and your radio stations, and you will lose your current trip OD reading.
 

n1das

TDIClub Enthusiast, Veteran Member
Joined
Jun 11, 2002
Location
Nashua, NH, USA
TDI
2014 BMW 535xd ///M-Sport, 2012 BMW X5 Xdrive35d, former 3x TDI owner
I am planning to change out my battery myself on my 2003 Jetta TDI in the near future. The changeout is going to be done for preventative maintenance (before the battery fails). I do not want to be stranded somewhere. I did not know until today that you need to keep voltage on the computer during the changeout process. I have located an inexpensive 9 volt computer memory saver that I can purchase.

Questions:

1. What happens to the computer if power is totally lost? Will the car not start at all with the new battery?

2. How many other makes/models of vehicles require a computer memory saver hookup for a battery changeout? I never had any known problems with my battery changeouts of my previous vehicles (1993 Mercury Sable & 1995 Chevrolet P/U).

Thanks in Advance.
No "memory saver" required for a TDI.

IIRC, some gasser models might need to go through a throttle body calibration procedure after connecting up the the new battery but this procedure is N/A for diesels including TDIs.

If the radio head unit is the original, no radio code should be needed because the car and radio should recognize each other as belonging together. If the head unit has been swapped, the radio code might be needed. If the head unit is an aftermarket system, all bets are off.

In your case the most you should need to do is reset the clock on the instrument cluster after the swap.

My 02 Golf TDI (don't have it anymore, sold it a while ago) has sat parked for 2 weeks without a battery in it and without any ill effects afterwards. The most I had to do after reinstalling the battery and getting the car back on the road was reset the clock.

Good luck.
 

Vince Waldon

Top Post Dawg
Joined
Apr 25, 2009
Location
Edmonton AB Canada
TDI
2001 ALH Jetta, 2003 ALH Wagon, 2005 BEW Wagon
Yup some gassers benefit from a throttle-body adaptation after a long power loss but on our TDIs no worries... I've had batteries in and out of my two 2001 Jettas repeatedly over the years without issue.
 

TDI in MT

Veteran Member
Joined
Apr 2, 2013
Location
Montana, USA
TDI
none, sold it.
An old thread, but I wonder how can I prevent having to reset the time & anti-pinch on the windows (and keep the trip odometer) when the battery is disconnected?

My radio didn't lose anything, but I had to reset the time, anti-pinch and lost the trip odo when I disconnected the battery today. Irritating, especially the trip odo since I'm trying to record MPG.
 

Powder Hound

Top Post Dawg
Joined
Oct 25, 1999
Location
Under a Bridge, Crestview, FL, USA
TDI
'00 Golf 4dr White 5sp, '02 Jettachero 5sp, Wife's '03 NB Platinum Gray auto(!)
Well, if you are that worried about those few things, then a memory saver that connects through the power port in the dash will have to do. Another possibility (although I've never tried either) would be to plug a solar cell into the OBD port and do the swap in the sun.

cheers, PH
 

Strykeviper

Veteran Member
Joined
Mar 17, 2010
Location
Orlando, FL
TDI
2000 Jetta GLS 5 speed swap, 2002 Jetta Wagon, 2015 Passat SEL, 2013 Jetta Sportwagen
Snapping a pic of the trip odometer works well too :) but it won't help with the clock and radio presets.
 

Scoutx

Veteran Member
Joined
Jun 4, 2012
Location
Virginia
TDI
2012 Jetta (6MT) - 1000 Mile Club (retired)___ 2015 Jetta SEL (6MT)
One last piece of advice.

Remove the negative lead first...and install it last.

Helps avoid inadvertent grounding of the positive to the frame with your metal wrench. :)
 
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