Getting ready to finish lighting upgrades to my coupe. Quick question: How long can you keep the battery (negative/ground) disconnected before you may encounter any issues with the system after reconnect? No expert, but my upgrades may have to be spaced over a day and I want to ensure that any of the controls internally can go without power for an extended period of time. Thanks for any information.

 

I expect somewhere in the range of 10-50 years. There is absolutely zero issues with any of the electronics with leaving them unplugged; the only reason I gave any sort of time range at all is because of deterioration, which would happen whether the equipment was plugged in or not (and probably accelerated by being plugged in).

For example, I have a couple of extremely old hard drives (5 1/4 inch bigfoot drives) still new in the box, I am 100% certain they would work if I plugged them in to some old PC.

Short answer: Don't worry about it.

 

Any data stored in the volatile memory of the various ECMs will be lost within milliseconds. Nonvolatile memory is persistent. Once the battery is disconnected, the Earth stands still and the various components will have no idea if they have been powered down for five hours, five days, or five months.

Keep in mind that your battery will slowly discharge, even while disconnected from the vehicle, so if you expect your project to take more than a couple of weeks, you'll need a battery maintainer. If you don't already have one, I'd recommend a CTEK. There are several different supporting vendors that can hook you up.

 

Thanks. Well since that range will effectively out live me by 30 or so years I wont worry about it. I did think that I would lose some preset functions like radio station pre-sets, seat position memory, etc. and also some engine trims (probably relearned after driving again). So i will wait to see if any body has any other insight.

Thanks. I dont expect it to take more than a day and a half, so discharge should not be an issue. It is my daily driver so it has not required a battery tender to date and living in Florida it has no seasonal down time.

 

The things that you will find that go away are: (this is a short list and the ones that I remember of the top of my head)

1. % Oil remaining will reset to 100. Figure out what is left and estimate when it will need to be changed next. If you are at 20% remaining, once its reset back to 100,, change the oil at 80% remaining.

2. Average Fuel mileage reset to zero

3. Hud Settings reset to Factory preset.

4. Learned Idle will reset back to the factory idle. It will relearn over a short on the road drive session and you shouldnt really notice any thing.

5. Your OBD2 Emissions Status Ready will all reset to NOT READY and will require a number of drive cycles to reset to ready. Only important to know if you have a state emissions test due very soon!

6. Long Term Fuel Trims will be lost but will relearn over a short drive period.

7. Average speed, & Trip odometer readings in Trip A & B will reser to zero

8. If you have a security code in the radio, it will lock out and need to be re-entered. If you dont, NO ISSUES.

9. On my 02 Z, the MEMORY 1 and MEMORY 2 stuff resets to factory reset settings and I have to relearn all of those pefered settings.

The HVAC will reset back to the factory preset vent positions, mode and temps

All the stuff that you lose/resets is no big deal other than the % oil remaining.

All of the vital tuning info all retained in NON VOLITAL Memory and will not be effected

 

To the OP, I don't want to hijack your thread, Bill how can you determine if the radio has security code? What do you do if it does and you disconnect the battery to do mods? Thanx, Fred

 

Fred

Go to the C5 TECH TIPS PAGE: https://www.corvetteforum.com/techti...=164&TopicID=1

Find the UNLOCK C5 RADIO AND DO THIS:

The
following procedure will give you a new code that you can use instead of
your personal code. Using this new code, you can �unlock� your radio and
then �re-lock� it with a new code if you
wish.

Prerequisites:
The radio must be in LOC mode NOT in INOP
mode.

Let me explain. If you have activated the Theft-Deterrent
feature of your radio and loose power, the radio goes into LOC (theftlock)
mode. With the ignition on, you must use the MN and HR buttons to enter
you personal code in order to unlock it (The instructions are on page 3-27
in your Y2K Owner�s manual). If you fail to enter the correct code eight
(8) times, the radio goes into INOP mode. You have to wait an hour with
the ignition on before the radio returns to LOC mode (go for a long drive
somewhere).

Procedure:
01. Turn the ignition ON (The radio
displays LOC)
02. Hold down the Radio Presets 2 and 3 buttons for six
seconds
03. The radio display changes from LOC to a three-digit number.
Write this number down. Don�t take forever, fifteen seconds max before the
next step.
04. Press the AM/FM button
05. The radio display changes
to another three-digit number. Write this number to the right of the first
one.
06. You now have a six-digit number, the first three digits are
from STEP 03 and the last three digits are form STEP 05
07. Call 1 800
537 5140
08. Press 1 then # (pound). You�ll hear �Invalid Code, try
again�
09. Press 139010 then # (pound). You will be asked to enter your
four or six digit code followed by * (start)
10. Enter the number from
STEP 6 then * (star)
11. Listen to the four-digit number and write it
down. It will be repeated twice
12. Turn the ignition ON (The radio
displays LOC)
13. Use the MN and HR buttons to enter the code from STEP
11
14. Press the AM/FM button. The radio display changes to
SEC

Your radio is now �un-locked� and usable. The Theft-Deterrent
feature is STILL active! If you want to disable it, use the instruction on
page 3-27 in your Y2K Owner�s manual. Use the code from STEP 11 instead of
your personal code.

Note: This tip originated from LOTZAHP, Austin
TX (credit must be given where credit is due). I verified it on an Y2K C5
with a locked radio - mine.

 

Thanx to the OP for indulging me and to Bill. I knew if anyone knew the answer it would be you. Thanx again.

 

No problem as I am not sure my radio in my 2000 has the lock enabled or not and this info will come in handy. Thanks to all.

 

Look for a red blinking light on the front panel of your radio with the ignition switch turned off. If yes, it indicates the locking feature has been enabled.

 

Ok, so disconnected the negative/ground from the battery. Then proceeded to install th ACA housings with HID low beams, converted the fogs to HID, and installed the Hi-4 harness from Radio Flyer along with the 55watt resistor on one side of the lows. Reconnected the negative/ground to test everything and the observed the following:
....my alarm system (factory) went off (horn beeping) immediately. had to hit the panic button on the fob to silence it.
....did lose my seat postion memory and had to reset.
...did not lose the "oil life remaining" percentage. It was at same percentage it was before disconnecting the battery, 70%.
...did not lose my radio pre-set channel selections. They were all still as they were before I started.

Started the car, no problem, checked the function of all the lights, all working as normal. Then shut down to re-install the headlight covers and shrouds. And this is where user error occured. Tightening down the rear 2 torx screws on the left cover and snapped off the tab on the cover. Managed to get the 2 side srews in for now and installed the shroud. On the other side no issues with re-installing the cover and shroud, but the gap at the front of the cover and the front bumper with the lights closed is wider than it was before I removed the lights. So will have to adjust that. Have to adjust the aim of the low beams somewhat, but over all everything looks good. Thanks to all for the input.