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2008 z51- after 5 days battery is drawn down enough so car wont start.
when testing I found a
.24 draw-.
.10 from the defroster circuit go fig.
.04 from the ECM module and .
.10 that magically disappeared after removal and re installation of the windshield washer fuse.?
40 milliamps for ECM also seems a bit excessive, but there isn't much you can do about it.
Typically, overall parasitic drain in newer vehicles should be 70 milliamps or less. When you test, you need to monitor the current draw over a few hours time. If you disconnect the battery to do the test, the computers all go through a reboot cycle so initial current flow will be higher. At the very least, give them 10 minutes to settle, but monitoring it over a longer period is best, as there are some circuits in the car that cycle on/off over time.
2008 z51- after 5 days battery is drawn down enough so car wont start.
when testing I found a
.24 draw-.
10 from the defroster circuit go fig.
.04 from the ECM module and .
10 that magically disappeared after removal and re installation of the windshield washer fuse.?
Is .04 high for the ECM?
Max current draw is RC of the battery divided by 4…100 minutes would be 25 milliamps…what ECM fuse did you see a 40 mA draw ???
I’ve got a very similar problem as described in this thread. Battery doesn’t go dead in a week but it will in 2 weeks. Parasitic draw after car goes to sleep can range between .320 and .650 amps. Strangely, you can sometimes hear what sounds like HVAC ductwork actuating under the dash intermittently when the car is parked and hasn’t been touched for days. At first I thought there was a mouse under there but it’s a mechanical apparatus under the dash. You can hear it outside the vehicle with the vehicle completely closed up but with the top and windows down, it can clearly be heard coming from underneath the dash. Since it’s very sporadic, I haven’t been able to get an amp reading while it’s doing it. The aforementioned readings are there when no noise is heard and the car appears to be asleep. I went through all the mini-fuses to no avail but didn’t know how to deal with the J-fuses; couldn’t get a reading on those and didn’t know how to get them out without damaging. Suggestions welcomed.
Yes, J-fuses are difficult to check but to remove them get a pair of the pliers pictured below to pull them out without damaging the plastic covers…so if you want to find what exactly is causing your drain you DON’T pull fuses but instead do a voltage drop check across each fuse…video below…if you “think” it may be HVAC related remove the HVAC/PWR SND fuse located at the BCM and see if that draw goes away before all the modules “go to sleep”.
Update-fixed one draw,it was the battery. After disconnecting the cables I found that I was still losing ..05 volts over night. Battery is only a year old. Then i remembered and article I read about and old man who use to drain his batteries take them apart clean the junk out of the case then put them back together and refill and the battery worked fine for a number of years. I thought maybe there is something small caught between the plates. removed battery from car shook it around then tested it. it only lost .001 after 3 days. Reinstalled now the battery only loses .015 volts over night. Now the defroster is still a problem, plugged the relay back in and the relay began to get just a little bit warm.
The circuit go to the switch with a connect that goes to the data bus (class 2 ser data ) if its not the switch I will be leaving the relay out (not needed I live in FLA.) I do have the wiring diagram.
I followed the procedure detailed in the YouTube video. It worked great except for the JCase fuses, and there are quite a few of those. You can check voltages across standard fuses that have exposed terminals but the JCase fuses have a cover that doesn’t allow access to the terminals. The covers appear to have snap on/off features but you’d have to remove the fuses to get access to them. I found no issues with any of the circuits with minifuses.
I also read in a blog that the problem could be in the alternator; a failed diode that’s allowing current to return to the battery. Any thoughts on this, and how to confirm it?
I followed the procedure detailed in the YouTube video. It worked great except for the JCase fuses, and there are quite a few of those. You can check voltages across standard fuses that have exposed terminals but the JCase fuses have a cover that doesn’t allow access to the terminals. The covers appear to have snap on/off features but you’d have to remove the fuses to get access to them. I found no issues with any of the circuits with minifuses.
I also read in a blog that the problem could be in the alternator; a failed diode that’s allowing current to return to the battery. Any thoughts on this, and how to confirm it?
Just disconnect the alternator B+ and see if the draw decreases.
Software update for the RCDLR to lower parasitic amp draw. Refer to this TSB: #07-06-03-001B: Dead Battery, No Crank/No Start (Reprogram Remote Control Door Lock Receiver (RCDLR) - (Mar 21, 2007)
Condition Some customers may comment on a dead battery after the vehicle has been parked for a extended period of time. Typically, the battery will last approximately two weeks, depending on the initial state of battery charge.
Cause A software anomaly within the remote control door lock receiver (RCDLR) causes an additional 30 mA draw on the battery when passive locking is enabled and the vehicle is parked.
First and best option for this issue, in my opinion, is to rule out a weak battery. Fully charge the battery. Use a good battery tester and make sure the battery can pass the load test. Theses cars often cannot sit more than two weeks without causing lower than optimal battery cranking amps. I keep mine on a battery maintainer if sitting more than two weeks and the battery is almost new.
parisitic draw
