Battery Power drain on 95 SC 300
02-04-17, 10:23 AM
#1
Driver School Candidate
Thread Starter
Battery Power drain on 95 SC 300
After Car sets for over 12 hours It kills the Battery New alternator and Battery over the last 2 months, but problem got more noticeable after. Got new Battery tested and Alternator, and they checked out good. I didn't want to deal with chasing down the problem until the weather got better so I got a temp solution and just switched off the battery with a switch for a while when I let it sit over night. It brought me a little time. But now I get a delay after reconnecting the Battery when starting the ignition, It's unresponsive for few seconds. After the car starts it never does it again. So this time I tried letting the car sit and leaving the battery connected for about 10 hours the same thing happened. So my question to a trouble shooter out there is there a relay sticking that could be the whole problem on the ignition system that could be causing the power drain?
Also I'm running on a replaced ECU for the last 3 years. A car this age I'm sure its time to replace electronics here and there, but I only have 158K on this one.
Also I'm running on a replaced ECU for the last 3 years. A car this age I'm sure its time to replace electronics here and there, but I only have 158K on this one.
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mrmax512 (02-13-17)
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mrmax512 (02-13-17)
02-05-17, 10:43 PM
#4
Instructor
I just had this problem with my car. It took me a few days to figure out going around with a Voltmeter to find the drain.
Turns out the CD changer in the back of the car is always powered and shuts itself down when it's ready to play. However, in my case, while driving the changer was not working at all it kept trying to read the tracks and making all sorts of noises trying to load the CD's etc. Basically, while it's doing this it kills the battery when the car is off, so the easy first was to keep the loading door open or remove the cartridge. I eventually removed the whole unit and repaired it somehow (see my other posts).
I'm betting that's the source of the drain.
Turns out the CD changer in the back of the car is always powered and shuts itself down when it's ready to play. However, in my case, while driving the changer was not working at all it kept trying to read the tracks and making all sorts of noises trying to load the CD's etc. Basically, while it's doing this it kills the battery when the car is off, so the easy first was to keep the loading door open or remove the cartridge. I eventually removed the whole unit and repaired it somehow (see my other posts).
I'm betting that's the source of the drain.
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mrmax512 (02-13-17)
02-13-17, 08:48 PM
#6
It could be as simple as your corroded battery connectors, or loose connection between battery and starter. Also if you have a build up of acid on your terminals and corrosion it's not getting juice to your starter, and it's so easy to overlook those connectors.. These cars are old new terminals make a huge difference in a power delivery.
my battery was relocated to the rear about a month ago with all new terminals and 0 gauge wire i get solid crank and it feels better that before.
oops I read you got it under control
my battery was relocated to the rear about a month ago with all new terminals and 0 gauge wire i get solid crank and it feels better that before.
oops I read you got it under control
02-14-17, 03:04 AM
#7
I notice in my sc400 that the boot light will switch on with the boot only being unlatched.
The way I found out was by accident. I happen to have the parcel shelf off and notice the boot light was on!
The other battery drain I had was from an electric after market antenna I had fitted. It came out of my old RX4 coupe so was already old. It worked for a while and then one day the motor in it decided it didn't want to work any more but was shorting via the windings so it only got hot not a complete fuse blow. I hadn't noticed it as I used the car every day but not the radio.
Long story short disconnected electric antenna and no more flat battery.
Another one that you have already ruled out is the alternator diodes go short circuit and suck the battery dry but isn't a complete short. Very similar problem your experiencing but as you said you have replaced it, and I'm assuming it is new and been checked.
Look forward to what you find.
The way I found out was by accident. I happen to have the parcel shelf off and notice the boot light was on!
The other battery drain I had was from an electric after market antenna I had fitted. It came out of my old RX4 coupe so was already old. It worked for a while and then one day the motor in it decided it didn't want to work any more but was shorting via the windings so it only got hot not a complete fuse blow. I hadn't noticed it as I used the car every day but not the radio.
Long story short disconnected electric antenna and no more flat battery.
Another one that you have already ruled out is the alternator diodes go short circuit and suck the battery dry but isn't a complete short. Very similar problem your experiencing but as you said you have replaced it, and I'm assuming it is new and been checked.
Look forward to what you find.
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03-18-17, 09:39 AM
#8
Driver School Candidate
Thread Starter
I ended up taking out the aftermarket stereo head unit and reinstalling the factory unit. I had made a modification so that the factory woofer would work with the aftermarket head unit and had to solder those two wires (black and white) back to the factory plug. As I was soldering I could hear the woofer popping with the ignition off. So to me it seems that this amp was getting power all the time and the aftermarket never turned it off. So now after installing the factory unit back after 20 hours with the battery staying connected she fired right up, no power drain. Thanks for your reply's, I'll post again if this didn't solve the problem.
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