66ImpalaLT1

Sunday night I was doing some logging with EFILive and left the cable connected to the car. I got a ride to work with my roommate yesterday so It was connected for about 38 hours. This morning the car's battery was dead.

Does the Autotap V2 cable draw power from the car when the car is off and the laptop is not connected?

Thanks,
Eric

dissonance

no autotap does not pull any power while the car is off, the obd2 port is off when the car is off.

sounds like you have something else wrong, i leave my autotap cable pluged in all the time.

66ImpalaLT1

Maybe there is something different about Corvettes because I get a few seconds of data after I turn off the car and remove the key.

If this is unrelated to me leaving the Autotap cable connected, I'm suprised I didnt have a problem sunday, because the car had not been driven for 48 hours when I took for a drive to log calculated ve.

I double checked the interior lights this morning, even though I'm sure they have drain protection.

Eric

EFILive

iTrader: (2)

Actually, yes it does draw power all the time even if the key is off, even if there is no laptop.
The OBDII connector supplies +12V ALL the time.
n fact the PCM is always on and there is always data being sent over the class-2 data bus.

This is the warning in the EFILive V6 user manual:

The interface cable draws power from the vehicle’s battery, even when the ignition is switched off. While it does not draw a lot of power, if left connected for a significant length of time (i.e. overnight), it will drain the battery, even if it is not connected to a laptop or being used by EFILive.

66ImpalaLT1

Thanks Paul, I'm glad to know its not a more serious problem with my car.

I wont forgot to unplug it next time.

Eric

blk~2000~Z28

Hey EFIliveV5 I sent you a PM. did you get it?

EFILive

iTrader: (2)

My browser kills popups - so I didn't see it.
I'll send you a reply.
Paul

dissonance

Ok diss is wrong about the power "ping 2 and 16 have power" 2 is bus+ but none of the other pins are active.

I have had my autotap cable plugged in for more then 30days "no starts" and have never had a problem. I also leave the cable plugged in over night and over the weekend with out starting the car, haven't had a problem. I know the pcm has power all the time, with the alarm armed and autotap cable plug in I have never had an issues. My stock battery lasted five years "two of them with autotap cable plugged in over night" and my new battery is going strong, I also leave my power converter dc/ac for my laptop plugged in most of the time to.

So I will say again you might have something else wrong? Weak battery? Ever checked the battery’s eye? There is a small hole with a green or black flot. Green=good black=bad my stock battery went black but the car started fine but if ran any kinda load on the car for a few min’s it would not start. you can only do this with the stock ac delco battery

With the key off I get no data across the bus. I have a 98 maybe different?

EFILive

iTrader: (2)

I agree, one should not expect the battery to drain overnight - simply because the autotap cable is plugged in. It probably draws far less power than the PCM itself - which is on all the time.

I suspect that when some customers have complained of a flat battery because they left the cable plugged in overnight, what they nelglect to say is that the ignition was also left switched on overnight. (I'm not saying that is the cause of Eric's flat battery - there may be other causes, like you say).

The warning is probably a little severe, but if it saves one person from having a flat battery then it is worth it.

Regards
Paul

66ImpalaLT1

I did not leave the keys in, or on, and none of the lights were left on. Its certainly possible that my 4 1/2 year old battery is on its way out.

Is it probable that having the cable connected prevented some of the many control modules in the corvette from going to "sleep mode" or whatever?

Eric

EFILive

iTrader: (2)

The specs for the cable are that it draws 10mA, which will not (by itself) flatten your battery overnight. And as Dissonance says, probably not in a month either. So dissonance, I stand corrected on that count.

If you disconnect the cable from the laptop before disconnecting EFILive or closing the EFILive application then the cable *will* be left in a state where it continues to "interact" with other modules.

To prevent that, we recommend that you should disconnect using the disconnect icon in EFILive OR unplug the cable from the vehicle.

Paul

66ImpalaLT1

I may not have closed the application first. This wasnt just overnight, it was connected for about 40 hours straight.

Thanks Paul.

dissonance

Well if you mean you closed the lid on the laptop and it did not go in to hibernation… then you might be on to something but if you think the laptop will only run for a max of 3 hours with the LCD off? I have done that something before, now not disconnecting the logging software I’m not sure of, I can tell you this; I close the lid on my laptop before the car is off all the time, then power it backup and it picks right back up almost every time.

I don’t want to seem like this about who is right who is wrong, EFIlive you know 100x more then I do about this, I’m just speaking from experience.

Why don’t you go and get a load test done on the car? That would rule out a power problem in the car.

Doc

iTrader: (9)

Battery! 4 1/2 years out in the heat of AZ-Oh yeah. The main enemy of our modern sealed "Maintenance Free," batteries is boil over of electrolyte due to heat. The Hydrometer "Eye," is only to make you feel good-kinda like the 99+temp gauges. That eye is only representative of 1 of 6 of the battery's cells. You could very well have a battery that has boiled over,-years of heat; and still have false security of the Green Glow.

66ImpalaLT1

I've only lived in arizona for 1 year, and at 7,000ft elevation its never hot. Its 52 degrees outside right now.

The car has been fine for 3 days now since I recharged it.

glitch77

I have drained my Optima red top battery twice because I left the cable plugged in. (Both overnight)

Your mileage may vary.

gojo

iTrader: (12)

Great timing. I was about to subject my car to the dealer.
I noticed a slightly weak battery last week. I didn't drive it from fri. afternoon until this morning and it was dead. Totally. The cable was plugged in, of course. Great to know. I was concerned that some of my electrical work was the issue.

dissonance

ok guys EFIlive said 10mA, your not going to run the battery down with that kind of amp pull, I have a red top also and I leave the cable and dc/ac converter plugged in all the time and I have never had a weak or drained battery

The pcm and radio pulls more power then the autotap cable does, so why don’t we see a drained battery everyday. Oh what about the alarm? It pulls power while the car is off.

I think you guys are over looking the facts that the autotap cable is not a power problem.

Autotap pulls 10 milliamps
the alarm LED in the dash pulls around 20 milliamps...
LED's 101

66ImpalaLT1

While it pulls 10ma, if left in a state to interact with other modules they could be drawing more power than normal.

Technoman64

iTrader: (6)

I agree with the person who said if the cable is left in a state of communication the power draw could increase and obviously it does. If the cable is still active on the bus and if it has forced other modules into a diagnostic state they might not shut down to a low power mode as they would be waiting for commands. I believe that when a Diagnostic request is made on the bus all modules acknowledge it. I am not sure how all of the modules react when just the PCM, BCM, etc is polled for information. Maybe the GM software engineers did not provide a means to check for this. ie-if the the bus has acknowledged a Diagnostic request and no other bus activity relating to diagnostics(or information retrieval) for a set period of time occurs the bus is released for Diagnostic duties. This could also be done with the software in the cable link.

I have been on the J1850 bus lately on my 99 reading data and requesting information. I will do some tests with an Ammeter connected to see how much power draw there is in different modes with key OFF after being ON. I can watch all activity on the bus regardless of which module is arbitrating for control of the bus. I can not at this time watch the CAN bus activity. I have the circuitry on my proto-type interface I just want to be sure I have some idea of what I am doing before attemting it. I also have 196k of memory available to log with in my interface adapter. Got to love Motorola one $10.00 chip has more memory and processing power than my first PC!($1,200.00) The integrated Byte-Data-Link-Controller(J-1850) module is nice also. It handles all of the bus arbitration and timing. I also have two CAN interface modules on the chip. For any of the electronics do it yourself guys out there feel free to contact me. Do NOT ask to buy assembled electronics from me as I will NOT provide this. I just want a handheld scan tool-data logger with a wide band O2 interface option. Since I cant buy one I am making one.

If an Auto-Tap cable user wanted to check current draw they could do the same with an Ammeter and then see how not shutting down(or the procedure used) the logging software affects current draw.

Please note that I am no expert on this. I just find it very interesting. If there is GM engineer that reads this and can correct any of my theories please do so.