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Discussion Starter #1
So, yesterday I made a phone call near my 2006 Murano. The car had been off for quite a while. When my call began I couldn’t hear the other person in my phone’s earpiece because the phone had connected to my Bluetooth radio which was still powered on even though the car had been off for quite some time. I also found that the 12V power outlet in the center console to be on. So I knew it wasn’t just a faulty radio unit.
So I started searching for the accessory relay because I suspected that it was stuck “On”. I haven’t seen this before personally but I know it’s theoretically possible.
Thanks to the service manual available online I found that the accessory and blower motor relays are actually tucked on the back of the inside fusebox under the driver side knee bolster.
I didn’t have time last night to delve that deep so I left the car this way overnight and drove another car to work today.
Of course when I came home today to troubleshoot this issue the accessory power was no longer energized and when I started the car and shut it off it acted properly. So I take the blower relay and the accessory relay out for testing. They both act the same when activated and deactivated. They both have similar resistance readings across their contacts when energized.
So I attached some connectors to a standard BOSCH type relay and connected that in place of the Acc. relay for now to see if I have any further issues.
I think the only two possible problems would be a faulty Acc relay or a defective ignition switch. I know that relays don’t fail often but I’m at 241k miles and about 14 years with this car so I think it’s possible. I’m leaning away from a bad ignition switch because it’s not repeating the issue now. Also, when it was acting up yesterday the Acc circuit would drop out when cranking like it’s supposed to...but then would remain off after the key was turned off.
I’m posting today to ask if anyone has dealt with this at all on their Murano and to ask for you’re feedback or suggestions. Thanks in advance.
 

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Discussion Starter #2
I’ve eliminated several possibilities today. The phantom Acc power is NOT coming from the relay or the ignition switch.
It’s also not backfeeding from any other items that are on that circuit. My current theory is that the BCM is actually “leaking” the voltage and backfeeding the accessory circuit in the car. I’ll have to do some more testing but I think I know the pin that I have to test. I’ve also found a site online that says they can repair the BCM for $150 if that turns out to be the actual problem
 

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Just a thought, check for corroded ground connections...
 

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I’ve eliminated several possibilities today. The phantom Acc power is NOT coming from the relay or the ignition switch.
It’s also not backfeeding from any other items that are on that circuit. My current theory is that the BCM is actually “leaking” the voltage and backfeeding the accessory circuit in the car. I’ll have to do some more testing but I think I know the pin that I have to test. I’ve also found a site online that says they can repair the BCM for $150 if that turns out to be the actual problem
Did this issue happen again and were you actually able to measure this voltage leaking into the accessory circuit? On a side note, is this a factory radio or aftermarket--if the latter, were any modifications made in the wiring during installation?
 

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Discussion Starter #6
Did this issue happen again and were you actually able to measure this voltage leaking into the accessory circuit? On a side note, is this a factory radio or aftermarket--if the latter, were any modifications made in the wiring during installation?
It did happen again yesterday. My car has a remote starter and a complete aftermarket audio system. There have been no changes to the system in 8 years. I was able to learn that with the radio, heater controls and all other nearby modules unplugged (that might be on that Acc circuit) I could still read voltage on the radio Acc circuit and the charging outlet in the console. The other interesting detail is that while the Batt constant circuit was around 11.9-12.1V, the backfeeding ACC power was more like 10.8V. This also hints to me that it’s coming from somewhere it shouldn’t be since it’s subject to a such resistance.
 

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I may be missing something, but your battery voltage should be over ~12.3 volts for a happy electrical system, otherwise strange things can start happening...

Have you had your battery load tested? How old is it? Are the terminal posts free of corrosion and snug?

51366
 

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Discussion Starter #8
I may be missing something, but your battery voltage should be over ~12.3 volts for a happy electrical system, otherwise strange things can start happening...

Have you had your battery load tested? How old is it? Are the terminal posts free of corrosion and snug?

View attachment 51366
Good questions and suggestions. I didn’t take voltage measurements in this case until after the car had sat for 8 hours at my job. And then when I got out is when I realized the problem was still occurring. I then took about 15-20 mins of checking other parts and dash disassembly before I could actually meter the voltage at the radio connector. So I don’t know exactly how long the radio was on before I came out work, I had the door open for all the testing (dome lights) and I was testing voltage at the radio which means I’m checking voltage through that entire harness. Battery is new (2 weeks) with clean and tight terminals. Given the testing circumstances I’m confident that the battery and charging system are okay. Thank you for your help.
 

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The radio is one device that is supplied with both an Acc 12v for operation and a constant 12v for memory backup. It could be a potential source of the leak, so it may be worthwhile to unplug the radio and check to see if the Acc still has the voltage.
 

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Discussion Starter #10
The radio is one device that is supplied with both an Acc 12v for operation and a constant 12v for memory backup. It could be a potential source of the leak, so it may be worthwhile to unplug the radio and check to see if the Acc still has the voltage.
The voltage readings were done with the radio and all nearby modules unplugged. I was still reading voltage coming toward radio on the Acc wire.
 

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Discussion Starter #11
This issue has turned out to be an intermittent one so I haven’t been able to do further testing until today when it acted up again.

I’ve learned that if I pull the 15A radio fuse under the hood (near the battery) the “ghost power” to the ACC circuit disappears. So I put the fuse back in and tried disconnecting modules and relays in the areas affected by that fuse (according to the service manual) and I can’t cause the power to disappear any other way than pulling that fuse under the hood. I’ve also probably disconnected every module inside the car as well as the IPDM module under hood being removed just in case. I’ve also disconnected BCM, gauge cluster, ECM, heater controls, info screen display and controller, and rear defrost relay among many others.

I’m afraid that I may have a damaged body harness somewhere and that I’m in for a lot of work finding it.

Any other ideas, suggestions, or ridicule are all welcome.
 

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Have you measured the resistance between the constant 12v and Acc 12v when the key is out and everything is off? You probably need to disconnect the battery to avoid interference. If the resistance is a few ohms or less, you have a solid connection. If it's hundreds of ohms, it's probably leaking through some electronic device.
 

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Discussion Starter #13 (Edited)
I have found the problem.

The symptom changed, from periodic accessory power on when key off, to a fuse actually blowing as soon as I installed a new one. It’s the same fuse I could remove to stop the Acc power “bleed through”. Also my right turn signal started flashing very quickly.

So I knew I had a dead short now and it somehow tied in with the turn signals as well.

I also recently noticed this bad rusted hole in my rear passenger wheel well.

Soooo...to finally cut to the chase the hole allowed a lot of road spray to attack this plug which I think is for a factory amp or changer which I don’t have. The pink/black accessory wire is present there as well as many other wires. Cutting the wires before this plug has fixed my blown fuse issue, turn signal problem and I’m expecting it’s also going to fix the Acc bleed through problem. I’ll monitor it for a couple weeks before I call it solved.

This is a very odd issue that probably won’t help anyone else, but maybe
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I have found the problem.

The symptom changed, from periodic accessory power on when key off, to a fuse actually blowing as soon as I installed a new one. It’s the same fuse I could remove to stop the Acc power “bleed through”. Also my right turn signal started flashing very quickly.

So I knew I had a dead short now and it somehow tied in with the turn signals as well.

I also recently noticed this bad rusted hole in my rear passenger wheel well.

Soooo...to finally cut to the chase the hole allowed a lot of road spray to attack this plug which I think is for a factory amp or changer which I don’t have. The pink/black accessory wire is present there as well as many other wires. Cutting the wires before this plug has fixed my blown fuse issue, turn signal problem and I’m expecting it’s also going to fix the Acc bleed through problem. I’ll monitor it for a couple weeks before I call it solved.

This is a very odd issue that probably won’t help anyone else, but maybe
Well, people may not have this exact problem, but it's a good lesson on how corrosion can cause some real tough electrical problems to trouble-shoot. Thank you for reporting back on what you found.
 
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