Always had an issue with the battery discharging over a couple days of no use, but lately it does it in just a few hours, leaving me to beg a jump start to get home in the afternoon.

Ran through all of the tests, ammeter inline to negative terminal. I see a constant 1.97 amp draw, no higher or lower.

-Disconnected power seats.
-Unplugged Bose amp.
-Disconnected alternator, both main power wire and other connector as well afterwards.
-Removed every single fuse one at a time, both passenger footwell and engine compartment. Even unplugged main wires to footwell box.

Nothing made any difference in the draw.

Only wierdness is I also see a 1.69 amp current across the alternator wire to terminal when sitting with battery connected. Enough current to cause a small spark. Yet having it disconnected does not effect the amperage draw at the battery.

I do not see a spike when opening the door or any other action to trigger the BCM, just the constant 1.97, even after letting it sit for 30 minutes.

I assume unplugging the fuses would show whether the headlamp control module was the culprit.

Right now the car is not driveable, and that takes away a whole lot of stress relief therapy in my working day. I would appreciate some help here, as I don't want a garage static display.

Car in question is an '02 Z06, so only the driver seat is powered.

 

Obviously, pulling fuses one at a time is not going to do it. I suggest pulling everything (doing what ever you have to do to keep things organized) to completely isolate one fuse box at a time.

 

Just want to add that the head light control module is cool to touch, so apparently it is not the culprit.

I truly hate electrical problems.

 

Anything that you do to DISTURB the BCM during the test, will obscure the test. The BCM "MUST" not be distured during the test. That includes adding or removing fuses in circuits that the BCM monitors ie. interior lights..

This is where a set of service manuals comes in handy!

There are things that have power applied to them ALL the time. Its labled in the service manuals as "HOT at ALL TIMES"

Those are the fuses that you need to examine/pull.

Here are a few things that I have seen in the past cause severe parasitic current draw:

- Head Light control Module
- Aftermarket Ascessories plugged in or hard wired
- interior lighing remaining ON after BCM sleep mode (examine the car in the dark!
- passengers or drivers seat control module driving the seat after shut down (bad seat multifunction switch)
- Alternator (Use the amp meter in series with the BATT terminal on the back of the alternator and see what the current draw is. It should be ZERO!
-
Chech all tha and get back to us.

BC

 

I did wait 30 minutes between tests, and did not pull fuses till the very last attempt.

- Head Light control Module
Cool to touch.

- Aftermarket Ascessories plugged in or hard wired
None were plugged in, disconnected aftermarket amp power wire as well.

- interior lighing remaining ON after BCM sleep mode (examine the car in the dark!
Dark down here right now, no lights on at all.

- passengers or drivers seat control module driving the seat after shut down (bad seat multifunction switch)
Z06, only driver side powered, it is unplugged under seat.

- Alternator (Use the amp meter in series with the BATT terminal on the back of the alternator and see what the current draw is. It should be ZERO!
Power wire disconnected from alternator, no change in current draw, solid 1.97 amps. It does show a current draw with battery connected, right at 1.69 amps, but with it not connected, assuming that was the problem, there should be no draw.

 

In NOT quite sure I understand your last statement:

"- Alternator (Use the amp meter in series with the BATT terminal on the back of the alternator and see what the current draw is. It should be ZERO!
Power wire disconnected from alternator, no change in current draw, solid 1.97 amps. It does show a current draw with battery connected, right at 1.69 amps, but with it not connected, assuming that was the problem, there should be no draw. "

Please explain.

More troubleshooting. The Ignition Switch can have a "HOT in RUN & ACC" contact welded shut thus powering up a module after shutdown. Disconnect the ignition switch and see if you drop the current draw.

Im brain storming!

The B+ terminal on the engine compartment fuse box has TWO wires on it. One wire is power from the battery to the box and the other wire is power to the passengers compartment fuse box. Disconnect the wire to the passengers fuse box and insert the amp meter between that box and the B+ terminal. That will tell you if a circuit in the passenger's compartment fuse box is causing the current draw.

BC

 

I mean there IS 1.69 amp current when I disconnect the alternator and run the ammeter in series between the power cable and the terminal.

However, leaving that wire disconnected and returning to run the test on the battery negative terminal, the power drain there remains unchanged at 1.97 amps.

 

Are you allowing it to sit idle for the FULL 15 min (on some cars it may take 12-15 min to completly go into the sleep mode)

Try the couple of troubleshooting step that I recommended and see what you get.

BC

 

Follow Bill's suggestions to the letter if you want this resolved quickly. I suggest disconnecting the wires from the starter terminal B. Make sure you disconnect the battery first. Remove all wires from terminal B and protect the ends, hook up the battery, and repeat the current draw eval.

 

With the B+ terminal wires disconnected, there is still a 1.7 amp current in series on the negative terminal of the battery. The only way that drops to .02 amps is if I unplug both connections from the alternator as well (new alternator swapped in, same result).

There is 1.94 amp current when the battery is connected and I check inline on the B+ terminal and the positive battery terminal (all wires disconnected from B+ terminal).

I am to the point of finding a chicken and reading up on Voodoo for Dummies.

 

Did you disconnect the starter?

 

OK,,,,Lets try this:

Insert the amp meter in series with the NEGATIVE battery terminal. Get the current draw reading: I dont think the BCM going to sleep matters any more. Something is eating almost 2 amps all the time. We just need to figure out what buss its on and then go from there,

Remove the passengers foot well feed wire OFF the B+ terminal and see what the reading is:



Pull the battery wire off the engine compartment B+ terminal. You SHOULD see ZERO AMPs.

 

Baseline, ammeter hooked up inline series to negative terminal of battery, all B+ lug wires connected. Loose wire is aftermarket amp, has been disconnected for entire test.



With the power line to the passenger footwell fuseblock disconnected from B+:



Finally all lines to the B+ terminal disconnected:



Battery shows as good under load test, and by the sticker was mfg in May 2008. Battery trickle charger has also been disconnected during the entire diagnosis testing.

 

BINGO! The ONLY thing left in the circuit is the Starter SOLENOID and the Alternator. Heres the schematic that you need:



With ALL the wres removed from the B+ terminal, disconnect the alyernator next and see if it dorps to zero.

 

Note: This is a brand new alternator, installed today. Readings on it are identical to the old one.

Power wire disconnected, slight drop in current:



Control wire lead disconnected from alternator:

 

Hmmmm...I wonder what that means.......?

 

Before you blame the alternator,,,look at the schematic. Pins B & C control the alternator. One of the pins (PIN B) is the generator turn on signal. You may have a PCM issue! Install the amp meter between one pin in the connector and the corresponding pin in the alternator and figure out what one is drawing current.

BC

 

Bill, you have PM.

 

Ian

Byron and I have been discussing your issue. If you look at a 98 service manual and a 2002 service manual, the schematics for the CONTROL circuit of the alternator look very different.

What is the part number of the alternator that you have installed??

Bill

 

Bear in mind gentlemen, the OP had this current draw with his original alt. and the replacement.