Battery Disconnect

[Perry Mitchell]

I have read that disconnecting the battery for storage, the ECU will loose all it's tuning memory and that a low fused power wire should be installed to prevent this from happening.. I know the radio presets and the clock will be lost but what about the ECU? Also, would this be true for my '84 Corvette?

[HAWAIIZR-1]

I have been doing this since 2003 on my C4 Zs and never had an issue of tuning memory loss; only clock/radio presets.


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[Paul Workman]

Perry, you may be thinking of clearing the codes stored in the ECM when disconnecting the battery. The calibration tables are not affected by disconnecting the battery. In fact, IIRC several places in the factory service manual (FSM) refers to disconnecting the battery for various reasons involving repair OR clearing old codes stored in memory.

For example, sometimes the FSM directs you to disconnect the battery to clear the (old) stored codes so that if a particular code reappears, you know it was logged after the battery was reconnected and not before.

[Perry Mitchell]

Thank you for the replies. Paul, what you said is true but I wonder why some car makers say to connect another power source to the car when replacing batteries. Is it to simply keep the radio and clock working? I know my 84 Corvette runs like poo after disconnecting the battery for a time until I take it for a drive to what I thought was to get the ECU back on line.

[Corvette95]

The thing about battery disconnects and why I don't use them is the a//c programmer. This is just my opinion, but if you disconnect your battery, make sure your temperature is set to default 75 (this is good for storage as well to prevent blend door from sticking to the side of the heater box). Especially on the 90, it can take several minutes for the blend door to re-calibrate and sometime is fails. GM updated the 90 programmer for this very reason.

[XfireZ51]

I typically disconnect (-) batt cable during the winter. What happens w fueling is that your BLMs get reset to 128. As u drive the car, you will eventually get back to the level of tune you were at b4 pulling the batt cable.

[Dynomite]

I use the Battery Disconnect Switch on everything including Corvettes even if I only park them for a few days :thumbsup:

The Battery Disconnect Switch TIPS (http://www.corvetteforum.com/forums/c4-zr-1-discussion/3005470-tech-info-lt5-modifications-rebuild-tricks-500-hp-8.html#post1587653767)

Tractors, ATVs, Corvettes, Trucks, cars start up even over winter as if starting with a new battery.

The Battery Disconnect Switch also acts as a great theft deterrent :cheers:

[Perry Mitchell]

I typically disconnect (-) batt cable during the winter. What happens w fueling is that your BLMs get reset to 128. As u drive the car, you will eventually get back to the level of tune you were at b4 pulling the batt cable.
Thank you. Finally an explanation that makes sense to me.