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    09 P71 radio

    Hey I got a question for you guys. I have an 09 p71 with the fleet 4 button radio. I got an adaptor harness from replacement radios so I could put a higher end radio in. Well I got everything installed and have been driving it pretty much every day. The car sat for a day while I drove my 17 gt. Today I went to get into it and it was completely dead. No clicks nothing. I did notice that after I installed the radio startups were a tiny bit slower but not like a battery is about to go dead kind of slow. It’s possible the amp in that radio is going and draining the battery but only after a day of sitting? I called the company that makes the harness asking him if it was possible that maybe the harness was intermittently making contact with ground or something was pinned incorrectly and he immediately got on his high horse and ranted about how it’s not possible and it’s the radio. Perhaps it is the radio but could it completely drain the battery after like 24 hours? I find that hard to believe but I’m no electrical engineer. What do you guys think?


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    #2
    If you got the battery/ACC wires backwards it could cause this as the radio would stay on, but you would notice that. It may also just be coincidence and something else is dragging down the battery. I've had alternators fail in such a way that they work "fine" when the car is running but still draw 0.5-2 amps through the charge cable when "off" causing the battery to drain out overnight down to within 4 hours. Pull the fuse for the radio memory (always hot) circuit and put a multimeter across it in current (amps) mode and check what the off state current draw is. If it's above 100mA, something is wrong. Not sure what fuse that will be for yours. The one marked radio will be for the power when in run/ACC. That's not the one you want. From the manual PDF for your model year, I can't find what fuse is on the memory (batt) wire. If you have a service manual for that year car, you might be able to find that. The first thing to check is if there's excess power draw after 20 minutes of the car being off (give everything time to turn off completely). If you have more than 300mA of current draw from the battery at that point, something is wrong. If not, the battery just happened to die. I've had batteries up and die pretty quick too.

    Only two things are infinite, the universe and human stupidity, and I'm not sure about the former. -- Albert Einstein
    rides: 93 Crown Vic LX (The Red Velvet Cake), 2000 Crown Vic base model (Sandy), 2003 Expedition (the vacation beast)
    Originally posted by gadget73
    ... and it should all work like magic and unicorns and stuff.
    Originally posted by dmccaig
    Overhead, some poor bastards are flying in airplanes.

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      #3
      Thanks for the explanation I’ll check it out as soon as I can. My work schedule sucks but I should be able to work on it Sunday.


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        #4
        So I charged the battery and let the car run for a while so I could do the drain test on it the next day only to find it dead again the next day. A few days ago I again removed the battery to charge it then put it back in yesterday and even drove it to gas it up and let the alternator charge the battery too. Also I swapped back to the stock radio just to rule that out. That was around 10pm last night. About an hour ago I went outside and was greeted by a flat battery again. The same day I swapped the radio I put a new horn in it because the old one had an extra harness on it that was cut. Could that be the issue? It seems like the alternators are known to kill batteries too. Now I’ll charge it again...


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          #5
          Without checking for current draw and where it's actually going, if anywhere, it looks like a weak battery. A new battery won't solve the problem if it's actual current draw though. You need to check vehicle off current draw to make sure it's less than 300mA. Pull the negative cable and put a meter between the terminal and the cable in AMP mode. If you see more than 300mA, you'll need to find out where it's going.

          Only two things are infinite, the universe and human stupidity, and I'm not sure about the former. -- Albert Einstein
          rides: 93 Crown Vic LX (The Red Velvet Cake), 2000 Crown Vic base model (Sandy), 2003 Expedition (the vacation beast)
          Originally posted by gadget73
          ... and it should all work like magic and unicorns and stuff.
          Originally posted by dmccaig
          Overhead, some poor bastards are flying in airplanes.

          Comment


            #6
            With my schedule it’s hard to put the battery in, run it and give it some time to sit before I rip into it.

            I would agree about the battery but this is the second battery. I have a feeling it’s the horn circuit. The agency who owned it before me tapped into it for the siren, there might still be something somewhere hooked up that’s drawing power. That was the last thing I did before all this happened and you know what they say about that. Thanks I’ll try to get to it soon.


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              #7
              For tracing the current draw, there's no need to start the car if the battery is charged. Just hook it up and start tracing.

              Only two things are infinite, the universe and human stupidity, and I'm not sure about the former. -- Albert Einstein
              rides: 93 Crown Vic LX (The Red Velvet Cake), 2000 Crown Vic base model (Sandy), 2003 Expedition (the vacation beast)
              Originally posted by gadget73
              ... and it should all work like magic and unicorns and stuff.
              Originally posted by dmccaig
              Overhead, some poor bastards are flying in airplanes.

              Comment


                #8
                I only started it to get the battery all the way charged. I’ll try to get this done tomorrow before work.


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                  #9
                  I finally got around to tracing the current draw. I had my meter set to 10 amp and put it between the negative terminal and negative battery post. It was about .19 on the meter which would be too high if I’m not mistaken. So I pulled every fuse under the hood and the only one that made a difference was the ac clutch relay feed. If I took the fuse out it would drop to .12 which I don’t think is much. Then when I went to wiggle the relay for the ac clutch it jumped to over .3 so I swapped it for the relay for my horn (which doesn’t work anyway). No more jumping around. The other one that didn’t do much was for my cluster and 8 other circuits. You could hear clicking from the drivers side dash area when I reinserted it so it definitely is doing something with the car turned off but not much. I’m at a loss here, the battery is dead so I can’t do more testing. What more can I do? I’m thinking maybe it was the relay sticking open when I installed the horn then tried pressing it but I feel like it would’ve stuck on so I’m spitballing. Any thoughts?


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                    #10
                    Ok so I went and started pulling fuses again and it looks like 104 is my culprit. It provides power for the fuses 2, 4, 6, 8, 19, 21, 23, and 25 in the interior fuse box. All of these are related to the LCM so it looks like the LCM is at fault.


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                      #11
                      anything below 0.3 should be fine actually. 0.19 I think is actually normal for later models. I doubt there's anything actually wrong with the LCM. I think you've really just got a bum battery. The only other thing I would check is that the alternator is actually charging (voltage over 13.2) when the car is running.

                      Only two things are infinite, the universe and human stupidity, and I'm not sure about the former. -- Albert Einstein
                      rides: 93 Crown Vic LX (The Red Velvet Cake), 2000 Crown Vic base model (Sandy), 2003 Expedition (the vacation beast)
                      Originally posted by gadget73
                      ... and it should all work like magic and unicorns and stuff.
                      Originally posted by dmccaig
                      Overhead, some poor bastards are flying in airplanes.

                      Comment


                        #12
                        But this is the weird thing. The battery that was in it was fine up until I swapped the radio and horn then it died completely like 3 days later. Then I swapped in the new battery, but I only drove it a few days came back to it and it was flat dead too. Then I charged it, it started up fine and it died too. But the last time it lost its charge was odd. I put it in the car and had it run for 20 or so minutes with some driving. I let it sit for about 12 hours and it started up fine again. It sat for another about 8 hours and was completely flat. How does that make sense? And I looked around to make sure I was reading my meter correctly and everyone said with it on 10a a reading of 50 milliamperes would read as .05. Since my reading was .19 that’s almost 4 times as much, and with 50 milliamperes being the golden standard something is pulling down the battery at 4 times the rate it should. If I’m wrong please correct me.





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                          #13
                          I've noticed this with some meters. They are stupid with the decimal point on a couple of settings. That said, 0.05 would be 50mA on the 10A setting. Like I said before, 0.19 is not out of the realm of normal with all the body computer, security, keyless entry, etc, etc. I've also heard of folks getting bad batteries that die pretty quick. To test this, with it charged, have someone crank the car while you read the voltage across the battery. If it drops below to 11V or lower, it's got a bad cell and should be replaced under warranty. Otherwise, there's an intermittent issue that's draining the battery and that's going to be a huge pain to track down.

                          Only two things are infinite, the universe and human stupidity, and I'm not sure about the former. -- Albert Einstein
                          rides: 93 Crown Vic LX (The Red Velvet Cake), 2000 Crown Vic base model (Sandy), 2003 Expedition (the vacation beast)
                          Originally posted by gadget73
                          ... and it should all work like magic and unicorns and stuff.
                          Originally posted by dmccaig
                          Overhead, some poor bastards are flying in airplanes.

                          Comment


                            #14
                            Thanks. It seems to me, if that isn’t the problem, that it starts at night. It’ll be fine sitting during the day but it’ll kill it if it sits overnight even if that’s not that as long as during the day.


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                              #15
                              That is odd. Could be autolamp related if that's the case. If the headlight switch has an auto setting, turning it to OFF should test that theory.

                              Only two things are infinite, the universe and human stupidity, and I'm not sure about the former. -- Albert Einstein
                              rides: 93 Crown Vic LX (The Red Velvet Cake), 2000 Crown Vic base model (Sandy), 2003 Expedition (the vacation beast)
                              Originally posted by gadget73
                              ... and it should all work like magic and unicorns and stuff.
                              Originally posted by dmccaig
                              Overhead, some poor bastards are flying in airplanes.

                              Comment

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