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Have you checked the female pins at the fusebox power connector to see if they have tension and are making contact? The fusebox itself is a giant stamped-metal printed circuit and I've only ever seen one fail, and in any case you tried a second one. If there's 12V at the female pins but 2V with them hooked up, then there's resistance in one of those pins. The male pin being shiny doesn't mean the female is contacting it.
 

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Well, let me revise that. If there's 12V at the female pins but 2V with them hooked up, then there's either resistance in one of those pins or something downstream has a horrendous short that's sucking the circuit down. Back-probe the two white wires while they're connected. If you see 12V then check the pins as above, one of them isn't making full contact. If you see 2V when back-probed then something downstream is shorted.
 

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Discussion Starter · #23 ·
I’ve got 2.0 vdc at the male pin that goes to power the radio in the fuse box and 2.0 vdc to the ACC relay port in the fuse box #3 and 2.0 vdc with the key on. When that connector is pushed into the fuse box I get the same low readings at the cig lighter and female connector that plugs into the radio. That tells me the female connection is tight. I agree the fuse box was a very long shot but for $20 for a box and three relays not a bad deal. Pulling the fuse box in the engine bay seems to be PITA so I’m going to run a direct line from the battery to the two 12vdc inputs on the fuse box. I did clean the male pins on the fuse box and the female pins in the two white fat inbound wires from the engine bay. The female pins test 12 vdc when going to ground.
The only thing I can think of is where those two white wires connect to vehicle, thinking under the engine bay fuse box may have some corrosion on them. Looks like a bear to remove.

Just saw your second reply. I have 12vdc, both female connectors at the fuse box. I have 2.0 at the radio pin, and ACC pin at the relay on the fuse box with the two white feed wires connected. If there is any resistance going from 12 to 2 I’m looking for smoke. The drop occurs between the 12 vdc input at the fuse box and the male pins for the radio and cig lighter in the fuse box as nothing else is connected other than power to the key

once again I really appreciate your help
Len
 

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You can only get smoke if there's current being drawn, which there isn't much on the accessory circuit even if everything is switched on. That's Ohm's Law. If the Vdrop is 10V and the circuit only draws 10 milliamps, then the power generated in the bad connection will be 10 * 0.01 = 0.1 watts and it won't heat anything. If the circuits on the other side are drawing 10A then it's 10 * 10 = 100 watts and you get smoke aplenty. That 12V at the back of the white wires is telling you the power isn't getting through the connector. That's because the COM terminals of the Acc Relay and Blower Relay are both directly connected inside the fusebox to the WHT terminal 2L. So you simply need to find out where the disconnect is, and there are really just three places it can be, at 2L, at the female COM pin on the Acc Relay, or the female NC pin for the Acc Relay. Since the latter two have pretty much been ruled out by the new fusebox, I'd suggest pulling the connector and jump from the back of the harness pins where you know there's 12V to the male pins with gator jumpers. If everything wakes up then you know the female contacts in the harness connector are bad.
 

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PS - Looking back, I see you still haven't mentioned whether you checked the connection for the Acc Relay coil from the Ignition Switch, WHT/BLU on 4M. So the problem could still be in that wire or in your Ignition Switch. If 4M doesn't go hot then the Acc Relay won't turn on.
 

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Discussion Starter · #26 ·
PS - Looking back, I see you still haven't mentioned whether you checked the connection for the Acc Relay coil from the Ignition Switch, WHT/BLU on 4M. So the problem could still be in that wire or in your Ignition Switch. If 4M doesn't go hot then the Acc Relay won't turn on.
Tomorrows project…..head hurts from doing this. The good news is that everything is taken apart and easy to get to.

Again, many thanks!
 

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Discussion Starter · #27 ·
My wife walked by the truck….and the radio was on. No idea why. New radio, new relays, new battery and fuse block. 12vdc at all the correct terminal. All the connections and tight and lubed with dielectric grease. I shut the truck down about a week ago and the radio turned off after three seconds just like it was programmed. I have no idea what is causing this and worse yet I’m baffled as where to start………… again.
 

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The only thing that usually causes that is a bad radio (or a radio with bad firmware, which in the case of an aftermarket unit, you have no control over). If something in the truck is waking it up then it has to be the Acc input, but the thing is, unless that input is continuous, the radio should go back to sleep. To eliminate the possibility of stray voltage building up in the Acc circuit and tripping it, put a pulldown resistor on the yellow wire. A 3.3K 1/2 watt should suffice, something like this:

T-tap the yellow wire and connect one end of the resistor to it, then connect the other end of the resistor to a chassis ground. That will supply a "hard ground bias" to assure that when the Acc relay is open, the line will go to 0V and stay there. With that in place, if the radio still wakes up when it shouldn't, it's either a bum radio or there's something external that can wake it up that you're not aware of, like a bluetooth or WiFi link.
 

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Discussion Starter · #29 ·
The only thing that usually causes that is a bad radio (or a radio with bad firmware, which in the case of an aftermarket unit, you have no control over). If something in the truck is waking it up then it has to be the Acc input, but the thing is, unless that input is continuous, the radio should go back to sleep. To eliminate the possibility of stray voltage building up in the Acc circuit and tripping it, put a pulldown resistor on the yellow wire. A 3.3K 1/2 watt should suffice, something like this:

T-tap the yellow wire and connect one end of the resistor to it, then connect the other end of the resistor to a chassis ground. That will supply a "hard ground bias" to assure that when the Acc relay is open, the line will go to 0V and stay there. With that in place, if the radio still wakes up when it shouldn't, it's either a bum radio or there's something external that can wake it up that you're not aware of, like a bluetooth or WiFi link.
I’ll order the resistors tomorrow. The last radio did the same thing. There is no WiFi or Bluetooth where the truck is parked. Since the ACC relay, as well as all the other relays and fuse box are new to the truck there is stray voltage….somewhere. I’ll cut into the yellow wire at the connector where it connects to the radio harness and ground it where the radio grounds on the radio mount frame. All the keep alive wire on this radio does is show the time when you open the door. I’m just confused as to where the stray voltage comes from. On the surface it seems simple, two white 12vdc wires to the fuse box and everything emanates from there. I’ll check if the ignition switch for play tomorrow. Once again…..many thanks!

Len
 

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With the relay open, most or all of the loads on the Acc circuit are also open. That means if the Acc input gate on the radio is leaky, the leaked juice will have noplace to go and the gate will eventually self-trigger, waking the radio up. You don't disconnect the yellow wire, just T-tap it. The resistor gives any leaked voltage a way to ground when the Acc Relay is off, without disrupting anything when the relay is switched on.
 

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As it happens, I had an R52 Pathfinder radio with exactly the same "improper wakeup" issue show up this week. The problem is usually the radio itself, but this one wasn't. What I found after lots of poking around is that the Acc line to the radio was popping up to 12V for no reason. It was doing it even with the Acc Relay completely pulled out, and it wasn't a wiring issue because the Acc wire ohmed infinity to Batt+ with the relay out. Something on the Acc bus was leaking voltage and back-powering the circuit. In this case the candidates were the A/C Auto Amp, the Mirror Switch on the driver's door Master, and the cluster. I never did find out which because it was doing it very intermittently and the customer couldn't afford hours and hours of diag. So what I did to fix it was replace the Nissan 4-pin Acc Relay with a 5-pin "Bosch Box" type that pulled the Acc wire flat to ground whenever the relay turned off. It worked like a charm and everything else on the Acc wire still worked fine. So if you can identify which wire is waking your radio up, Acc or Ign, I'm pretty sure the same work-around would do the job for you.
 
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