g_murray

My old (Diehard) battery recently died so I ordered and received a new Optima Red Top (type 35).

The timing couldn't be worse - coz my NY state (OBD-ii) inspection is due this month (Sept.)

My initial plan was to maintain 12V to the car (to keep the computer/memory) 'happy' via jumper cables to the car (from another (good) battery) whilst I did the old-diehard/new-Optima swoperoonie.

Conventional wisdom says that if you 'cut power' to the car (for any length of time) that the OBD-ii 'readiness monitors' all go to 'OFF' - so I was trying to avoid this and also, thus, avoid having to do the 'drive cycle fandango' with the added pressure of the NY-inspection!

In short I was unable to maintain power to the car during the swop. I was pissed at myself but c'est la vie. The car was without power for almost 24 hours.

Figuring I'm now a candidate for the 'drive-cycle fandango' I connected my OBD-II code reader and, whilst it was 'connecting' (ISO-9141 keyword 2000), I took the time to enter the radio code so that I'd, at least, have some 'tunes' whilst driving around like a total spaz.

Lo and behold, ALL of my (8) readiness monitors were still showing "OK". I must admit, I was shocked! I turned the ignition to OFF and just sat there, dumfounded.

In case this was a case of 'operator error' I started from scratch.
(Sometimes the scanner will use 'old' readings unless you tell it to 'discard old readings' and start anew.)

Again, I got all (8) readiness monitors showing "OK".

So I turned the ignition to off again and did another 'reading'. Son of a gun - ALL 8 monitors were still showing "OK", with the code reader displaying "All readiness monitors are complete".

As I type this, I am still in shock ...but GRATEFUL! For now, not only do I have a car with a brand new battery but one that can go for state inspection 'any time'! AND I don't have to do the drive-cycle fandango either!
Also, all of my radio stations (both FM and AM) were still 'under' all the buttons - I did NOT have to re-tune/re-save anything.

So, my only conclusion is that the 'conventional wisdom' of letting the battery die (e.g. over the winter) or completely removing the battery does NOT (necessarily) totally upset the car's computer (ECU)!

Gerry
(A VERY happy camper!)

AOW162435

Gerry,
I would check the readiness codes one more time...


Andreas

g_murray

Trust me, Andreas, I am really scratching my head over this.
It's almost too good to be true.

I'll check them again this evening when I head home from work.

Gerry the scratcher

AOW162435

Andreas

DaveM993

I disconnect my battery every winter and have never had an issue with the "readiness" codes.

texas911

Just drive it a 50 miles after the batter swap.

The Brewmeister

I experienced the same thing with my VW GTI the last time I removed the battery.

Stealth 993

WOW, I would get a lotto ticket!! My battery went low, didn't even die, & it reset the codes. I dove the car for about 4 months & they still were not all reset.

I would drive the car & test again, this is to good to be true!

g_murray

Well, I got home yesterday and checked the 'status' of the p-car.

"All (8) readiness monitors are complete" !!!

Just for grins, I moseyed over to the wife's car (Ford Contour) and disconnected the battery for a minute and re-connected it. Sure enough, when I connected the OBD-II reader, it showed that her car was in a complete state of being "NOT READY". This is what I had expected so no biggie. My main reason for doing this was to make the 'last' reading, in my OBD-II reader, be that of a car that was "NOT ready". So! there would have to be a 'complete status change' -- as far as the code-reader is concerned -- for it to show any subsequent car as being 'OK' - if you get my drift.

So, then I went back to the p-car and did yet another OBD-II reading.

Again, the p-car shows "All 8 readiness monitors are complete".

So I'm not hallucinating!

Apparently, there's some NON-volatile memory in our p-cars (like a thumb drive?), that SAVES data even though the battery/power is completely taken away.

Believe me, I am NOT complaining. After all, here I am, after having installed a new battery, the car having had NO power, whatsoever, for over 24hrs, and all I have to do is simply RE-enter the radio code ...and I am good-to-go.

Thankyou Stuttgart !!!

Gerry

cmat

What year is your car? Is it possible that some years retain this information and others do not? Also, any aftermarket accessories like audio amplifiers with large storage capacitors that could hold a charge for a considerable time. Measuring system voltage with the battery disconnected would show this.

Just realised that you did have to enter the code for the radio so this is not the answer.

brucec59

That is indeed the mystery. The radio definately lost power. But the ECU (or whatever the code reader reads) did not, or the voltage didn't drop low enough for it to loose its memory. Maybe the radio is more sensative to low voltage?

g_murray

Hi CMAT,
'1996 C2' and pretty much stock (other than the ViperBob Bilstein/swaybar fandango).

Believe me I'm as stumped as you guyz are ...but no complaints -- esp. with the NY State Inspection this month!

Gerry

Slow Guy

In the future there is a cig. lighter plug in tool w/ 9v. battery that will help the vehicle remember these settings while you change your battery. They're available at auto parts stores and I would expect Radio Shack has them.

Here's what they look like but there are many vendors.
Battery memory

2Many Cars

That's what I use. They only last for a couple of hours (depending upon the car) but that's usually more than enough and they sure make life easier. By the way, they'll only work in cars that can be charged with a battery tender through the cig lighter too.

Texas993

Saw one at Walmart recently. In the auto service section near the batteries.