Radio draining battery

[RD911T]

So I did some reading and figured out how to find a current drain. With my DDM between the ground and the battery I was drawing 60 milliamps. When I pulled fuse number 3, the drain went away. This says window power and a PO had written radio by it. No wonder my battery tender jr was on all the time!

What would cause the radio to draw so much all the time? It's hard wired so I have to turn it off after I turn off the key. It's a Pioneer DEH-345 that was w the car when I got it. Car is a 71 T.

Tom

[nineball]

just a guess but it sounds like he may have wired the constant and switched power lines together. usually one is red (switched) and one is yellow (constant) on the back of the unit.

[FastCarFan]

When I got my '88 Carrera 11 years ago the battery kept draining if I didn't drive the car for a week or more. Turns out the switch in the door jamb (not sure what it is called) was sticking (i.e., it didn't pop out when the driver's door was opened). The cover had rotted away, & the "plunger" was stuck. Not sure if it is true with your earlier car, but in my car the accessories stay "hot" until the door is opened, & the sticking plunger meant that they stayed "hot" even after opening the door. In other words, the car never "knew" the door had been opened, so the accessories stayed hot.

Some WD-40 & a new rubber cover fixed the problem.

Does that make sense? Not sure that is your problem, but I thought my experience could help.

[donagain1]

Tom, while I have no firsthand knowledge of the wiring in a '71T, both of the previous replies outlined conditions that I found to be true with my '85. The constant power feed to the radio is designed to maintain presets for stations, etc, and usually has a separate lead into the radio for this purpose.

The power window circuit runs through a relay which remains activated until the doors have been opened and closed, presumably so that if you were sitting in the car after your drive, you could still roll up/down the windows by flicking the switches w/o turning the key back on. As my cabriolet top was usually down, I would oftentimes just lean in to start the car periodically to let it idle a bit, thinking I was putting a small charge to the battery, then reach back in to shut it off again. Turns out it was a dumb thing to do on many levels... draining the battery more by running the starter than it would recover by running it at idle for a brief period, excessive idling's negative impact on the oil-lubed parts, as well as for airflow and engine overheating reasons, but it never occured to me about the p/w relay remaining active because the doors were never opened and shut. After reading about the situation on a couple of different threads here, I put the meter to it much as you did. It amazed me how much current flow the activated relay draws. I've since refined my bad habits, and now keep one eye on the domelight to make sure that it lights prior to closing the door. If any of the above seems applicable in your situation, it may be the reason that you're looking for.

[Wiese]

I did a radio delete on my 73. Saved about 9 pounds of weight and no more drain on the battery for sure! This may not be what you are interested in pursuing but worth a thought!

[RD911T]

Originally Posted by nineball

just a guess but it sounds like he may have wired the constant and switched power lines together. usually one is red (switched) and one is yellow (constant) on the back of the unit.

Thanks Nineball, I'll check that.

[RD911T]

Originally Posted by donagain1

Tom, while I have no firsthand knowledge of the wiring in a '71T, both of the previous replies outlined conditions that I found to be true with my '85. The constant power feed to the radio is designed to maintain presets for stations, etc, and usually has a separate lead into the radio for this purpose.

The power window circuit runs through a relay which remains activated until the doors have been opened and closed, presumably so that if you were sitting in the car after your drive, you could still roll up/down the windows by flicking the switches w/o turning the key back on. As my cabriolet top was usually down, I would oftentimes just lean in to start the car periodically to let it idle a bit, thinking I was putting a small charge to the battery, then reach back in to shut it off again. Turns out it was a dumb thing to do on many levels... draining the battery more by running the starter than it would recover by running it at idle for a brief period, excessive idling's negative impact on the oil-lubed parts, as well as for airflow and engine overheating reasons, but it never occured to me about the p/w relay remaining active because the doors were never opened and shut. After reading about the situation on a couple of different threads here, I put the meter to it much as you did. It amazed me how much current flow the activated relay draws. I've since refined my bad habits, and now keep one eye on the domelight to make sure that it lights prior to closing the door. If any of the above seems applicable in your situation, it may be the reason that you're looking for.

I don't have power windows, but I have a circuit for them that the radio is wired in to. But this is interesting because whenever I connected the DMM I could here what I thought was a relay energizing. Maybe I just need to wire the radio into a more appropriate fuse.

Tom

[FastCarFan]

Originally Posted by donagain1

...I would oftentimes just lean in to start the car periodically to let it idle a bit....

Be careful. I remember reading - on this forum, I think - about a guy who reached in to start his 911, thinking it was in neutral. Well it wasn't, & the car took off & drove into another car.

I think it is safer to leave the car in gear as a back-up to the e-brake. My 2 cents.

[dan88911]

Originally Posted by FastCarFan

When I got my '88 Carrera 11 years ago the battery kept draining if I didn't drive the car for a week or more. Turns out the switch in the door jamb (not sure what it is called) was sticking (i.e., it didn't pop out when the driver's door was opened). The cover had rotted away, & the "plunger" was stuck. Not sure if it is true with your earlier car, but in my car the accessories stay "hot" until the door is opened, & the sticking plunger meant that they stayed "hot" even after opening the door. In other words, the car never "knew" the door had been opened, so the accessories stayed hot.

Some WD-40 & a new rubber cover fixed the problem.

Does that make sense? Not sure that is your problem, but I thought my experience could help.

The PO of my car said he had a similar problem. His wrench said it was the lamp switch in the trunk and removed the bulb. I have not fully checked this out. I suspected the alarm system. And removed it. Have had the car a couple years and keep a tender on it. And did have the drain problem after not driving for a week or so. The projects are many and time limited.

[911pcars]

The above suggestions have indicated some method of isolating the branch circuits on this fuse position. If you suspect the radio is the source of the current leak, disconnect all source voltage circuits leading to the radio, then retest for current drain. Once isolated, you can more accurately address the repair.

As for removing the radio to remove the drain, that's kind of a drastic fix unless it's already on the project list. What if the power window circuit was the source? Remove those pesky PW motors too?

Sherwood

[RD911T]

Solid advice Sherwood. Thanks for your input. I really want to keep my radio or replace it with another if it is the problem. I love the wail of the flat six, but I love music too and have connected that in my mind to part of the enjoyment of driving since I could drive.

Tom