Batboard

A mechanic told me to never disconnect the battery on late model Dodge trucks. He said the computer would loose some programming and the transmission will not shift correctly. This may be true because auto parts stores sell a 9 volt battery connector with clip leads to use for computer power when batteries are replaced.

I have never heard of this. I just did a fleet of 87 Dodge 1/2, 3/4, and 1-ton trucks (about 3 months ago) and disconnected the battery on everyone of them. Granted they weren't disconnected long, just long enough to move the terminal that connects to the power distribution box and slide the ring terminal on and put it back. Never heard anything about any problems.

And these guys will complain about anything!!

If that is true...what piss-poor engineer designed THAT system? ..leaving the lights on (killing the battery) will screw-up the computer??? Nobody in their right mind would put up with that after paying the price tag on a new truck...Z

I believe that deal from Autozone is just another gimmick that someone is trying to sell and make some money off of suckers. Don't fall for the bait.

Well, it's kinda BS and it's kinda not.

A modern car computer stores its programming info much like any RSS prog'd /\/\ radio does- in EEPROM memory. Disconnecting the battery on either of these products does no harm to the contents of the EEPROM.

However, there is some run-time data stored in the computer's RAM...things that the computer has "learned" about the car's operating environment. Think of this as a user-scan list, or something. Disconnecting the battery does affect this memory (i.e.: you'll notice that it runs a little different), but only for a day or so, until it re-learns what was erased.

The 9-volt batteries are sold for convienience only- so that you don't have to reprogram your AM/FM every time you remove the battery.

Hope this helps.

As the owner of a Dodge Ram PU that has had the battery disconnected many times while installing/removing goodies and the info is straight from Dodge Service:

After you reconnect the battery, start the vehicle, let it idle without reving/driving, etc. for ten minutes and the computer will reset itself.

I have one of the little cigarette lighter/9V battery thingys that maintain the AM/FM radio channels for the customer after you disconnect the battery to do install work. It's just a nice touch so he doesn't have to reenter all the channels and settings.

Unless the customer has given you a hard time in the past, then I set ALL his channels to the same Mexican radio station and turn the volume wide open

That's BS.

ANY modern PCM controlled vehicle will lose it's volative memory when the battery is disconnect, BUT......

This is engineered into the system. After volatile memory fades, you need to drive the vehicle for several miles to re-establish fuel/ignition maps, tranny shift scheduling and other parameters. It may shift funny for a mile or so, but after that, all is fine.

The manufacturers couldn't build any vehicle like descibed in the past text, as a simple dead battery would blow up transmissions left and right and have to be covered under warranty.

It's just a bunch of bull from somebody that has no clue- just like the one you always hear: "you have to disconnect the battery when welding" Just ground your welder at the location where you are welding and all will be fine- don't ground a welder or battery charger on the front of the car and weld on the rear (or jump start) otherwise a low voltage ground loop can occur.

Exactly what Jim said. What does that person suggest happens when you leave your headlights on and drain the battery? Buy a new tranny?

I knew it! *skips and jumps around!*!!!!

Sorry...off topic, but I had a bet running with one of the guys down at the shop. We were welding a hole on a Caprice...one of the newbies put the MIG ground at the trunk...he was welding the roof. Well, a seatbelt post appearently got hot enough to start a fire, and reading this now, it makes sense. The other guy agrees. This bags me 20 bucks. Thanks!

That guy was right..We did have that problem with a dodge intrepid 2003, it had to be towed out of our shop back to the dealer and they had to reprogram the vehicle computer...