Hi fellow owners: Top 4 fuses on my '09 Altima are not getting any power, this means a lot of sh*t on my car isn't working, the car starts and locking/unlocking works, wireless key and the radio works. But my heated seats, Blower Fan, shift lock disengage, instrument panel all are not working...I've narrowed it down to this circuit, but I am goddamn confused about what is happening

On paper the circuit is very straightforward, from the Bat => to the fuse link => connector =>Fuse Block [terminate], but there is no continuity between where my connection terminates and everything else upstream. But there is continuity between the components that feed this wire. Yes I made sure my leads were 100% connected properly ; I must have checked 25 times.

Another confusing part ? This wire is actually getting voltage, although it's 5V (which is why nothing is getting power) it's still coming from somewhere. Can you help

(https://www.nicoclub.com/service-manual ... 009/PG.pdf - Pg70)


Here are the wires actually..

Engine Bay:


Inside:

It's not clear where you mean the continuity stops, but the right tool is voltage drop and not continuity. If you have 12V at E1-1 and 5V on E1-3 then there's resistance inside the joint connector. If you have 12V on E1-3 but 5V at 1R, then the wire has a partial break between the JC and the fusebox. JC's are glorified busbars, have you had it apart to look at the contacts? It's also possible you have a rodent issue. On Altimas, a favorite place for chewing is right where the big bundle in the E-Harness goes through the firewall. It's almost impossible to see from up top, you need to pop the LHF wheel and peel back the rear half of the wheel well liner.

VStar650CL wrote: ↑

Sun Apr 17, 2022 8:01 pm

It's not clear where you mean the continuity stops...

There should be continuity from 1R to the ground side of the fuse link according to the diagram, shouldn't there ? For some reason I am not getting continuity from 1R to the fuse link or the E2 connector, which means there should be 0 voltage not the 5V I am seeing. I am really confused where the voltage is coming from.

VStar650CL wrote: ↑

Sun Apr 17, 2022 8:01 pm

impossible to see from up top, you need to pop the LHF wheel and peel back the rear half of the wheel well liner.

I peeled back the wheel liner: the harness looks fine to me besides grime & dirt...


One thing I neglected to mention was that there was an aftermarket remote starter installed that I took off , but there is a white wire which is cut & spliced which I am trying to eliminate as the source of the problem. See pics below.

I am trying to connect that wire to it's original location but I see no corresponding wire in the harness. Does anbody happen to know where or what this wire connects or snap a pic of it on their car ? My car is an 09 Sedan 2.5s

Before


After

I can't tell in those pics exactly which pin positions the two White wires are coming from, but the big slots at the top are pins 35~38 and the two nearest small ones are 24 and 34. There shouldn't be any White wires in any of them, so someone has to have re-pinned that connector. If you can identify which wire colors are in each of those slots, maybe I can figure out what they did. Refer to the pinout here on PCS-36:
https://www.nicoclub.com/service-manual ... %2FPCS.pdf

VStar650CL wrote: ↑

Mon Apr 18, 2022 4:16 pm

I can't tell in those pics exactly which pin positions the two White wires are coming from, but the big slots at the top are pins 35~38 and the two nearest small ones are 24 and 34. There shouldn't be any White wires in any of them, so someone has to have re-pinned that connector. If you can identify which wire colors are in each of those slots, maybe I can figure out what they did. Refer to the pinout here on PCS-36:
https://www.nicoclub.com/service-manual ... %2FPCS.pdf

Yeah that would be pin p37, which doesn't show up in the manual so I guess they wanted to ground something.
So this shouldn't have any impact on what my problem is right ?

I am feeling quite silly figuring out why a wire has 7 volt drop but is not damaged or frayed

Pin 37 does show in the manual, but it isn't stuffed. It connects to the coil driver for Ignition Relay #1 and the Fuel Pump Relay. See PCS-33:
https://www.nicoclub.com/service-manual ... %2FPCS.pdf

Hmm. That's a high-side driver supplying 12V to the coils, and grounding it externally would blow the IPDM. So they could only be using it a signal wire, not to manipulate anything. Very curious.

VStar650CL wrote: ↑

Mon Apr 18, 2022 6:11 pm

Hmm. That's a high-side driver supplying 12V to the coils, and grounding it externally would blow the IPDM. So they could only be using it a signal wire, not to manipulate anything. Very curious.

Sorry i'm confused. If I shouldn't connect this wire to a ground, where should I connect it ? Are you able to check in your car where this wire is connected ?

Pin 37 isn't supposed to connect anyplace, and connecting it to ground looks like it would blow up the IPDM's Fuel Pump relay driver. I can't say that for sure, it might have internal protection, but Nissan doesn't show much about the guts of their controllers. What concerns me is that you have two white wires there and the WD doesn't show any. Pin 38 should be going to a Red/White, not Just White. So somebody obviously did a lot of f#%king around with your wiring.

PS - I have an '04 and a '13, both QR's and no gen4's. So unless one comes into the shop for me, I can't help with a known-good vehicle.

VStar650CL wrote: ↑

Wed Apr 20, 2022 12:26 pm

PS - I have an '04 and a '13, both QR's and no gen4's. So unless one comes into the shop for me, I can't help with a known-good vehicle.

Understood, I will worry about this wire in a while. But going back to the Original post, the connector at 1R SHOULD have 12V (battery voltage), correct ? I am going to probe in the wire with a needle and find the point where the voltage drop is happening since 7 volt drop is insane,

Yah, voltage drop will serve you better than ohming it out. Wires do break "partially" and cause resistance conditions, we see it all too often.

VStar650CL wrote: ↑

Wed Apr 20, 2022 12:53 pm

Yah, voltage drop will serve you better than ohming it out. Wires do break "partially" and cause resistance conditions, we see it all too often.

Okay, I took a voltage reading just after the wire enters the inside of the car and it was reading ~7V. Then I went to take a voltage reading just before it enters the inside, and I found this:



Looks like corrosion from brutal salting and Canadian winters led to this, not suprising but damn the location of this problem was annoying as f*ck. Thanks a lot buddy.

I will update once I actually fix this, I am thinking of soldering a 14 gauge wire, do you think it will be good to carry enough current for the heated seats ?

That's going to be green on the inside, probably for 1/2" or so on both sides of the injury. If you repair it, use a new section and use solder shrinks for the splices to keep it waterproof. If you run a new conductor, shrink it temporarily to the old wire and use that as a pulling tool to yank the new conductor through the grommet.

14AWG is overkill if the heated seats are the only thing on the circuit. I think the OE conductor for the hot seats is 18AWG. The ampacity of 18AWG is 16A even at 90C operating temperature, and seat heaters usually suck about 50W on high, which is 3.6A. So that's plenty of safety margin.

If there's other stuff on the circuit, the ampacity at 90C for 16AWG is 18A, 14AWG is 25A. Gauge accordingly.

VStar650CL wrote: ↑

Wed Apr 20, 2022 5:33 pm

That's going to be green on the inside, probably for 1/2" or so on both sides of the injury. If you repair it, use a new section and use solder shrinks for the splices to keep it waterproof. If you run a new conductor, shrink it temporarily to the old wire and use that as a pulling tool to yank the new conductor through the grommet.

14AWG is overkill if the heated seats are the only thing on the circuit. I think the OE conductor for the hot seats is 18AWG. The ampacity of 18AWG is 16A even at 90C operating temperature, and seat heaters usually suck about 50W on high, which is 3.6A. So that's plenty of safety margin.

If there's other stuff on the circuit, the ampacity at 90C for 16AWG is 18A, 14AWG is 25A. Gauge accordingly.

I fixed the corroded wire with an 14 gauge wire and put back everything I took apart. I turned the iginition into the ACC mode and the accessories came back to life, and then I started the car. After 3-4 seconds the car started sputtering and turned off.

So Naturally my thought went to the white wire on Pin 37 because the car had plenty of gas, I went to take to go take a voltage reading by hooking it up to the Red lead and ground to the black lead. Well I think I accidentally f*cked my IPDM cause now it wont crank and the I cannot hear the fuel pump prime the gasoline.

Do I need a new IPDM ? Worst of all I noticed I had forgotten to plug back the MAF sensor which could be the cause of the sputtering and now I created a second problem for my self

An unplugged MAF will definitely make it sputter, and if the fuel pump wasn't running it wouldn't start at all. When you turn the key on the pump only runs for 1~2 seconds to prime the rail, then doesn't run again until you start the car. You'll have (I think) a P0102 in the system, clear it out and see if it starts running again.

Hmm, wait, I didn't see that it won't crank now. Better see if it will scan and what the codes are. You're right, you may have popped something.

PS - Just putting a voltmeter on pin 37 shouldn't have messed anything up, unless you accidentally had it set on amps or ohms. On volts it's high impedance, the IPDM circuitry wouldn't even have noticed it.

VStar650CL wrote: ↑

Sat Apr 23, 2022 5:16 pm

PS - Just putting a voltmeter on pin 37 shouldn't have messed anything up, unless you accidentally had it set on amps or ohms. On volts it's high impedance, the IPDM circuitry wouldn't even have noticed it.

I had it on amps, I wanted to see the performance of the circuit I fixed so I turned the seat heaters and checked the amperage and forgot to switch back to volts. Would that have fried the IPDM ? When I press the ignition switch all the accessories come on but don't hear the fuel pump prime the rails and when I press the button + brake no crank


I am replacing the IPDM tom, I found one at JY for 70. So swapping it out should be ok? Pin 37 should have battery voltage right ?

altima_slave wrote: ↑

Sat Apr 23, 2022 6:09 pm

I had it on amps, I wanted to see the performance of the circuit I fixed so I turned the seat heaters and checked the amperage and forgot to switch back to volts. Would that have fried the IPDM ? When I press the ignition switch all the accessories come on but don't hear the fuel pump prime the rails and when I press the button + brake no crank

I am replacing the IPDM tom, I found one at JY for 70. So swapping it out should be ok? Pin 37 should have battery voltage right ?

It's very likely having the meter on amps blew up the IPDM microprocessor, it would have grounded 37 through the ammeter shunt. So chances are the new IPDM will get you running again. Pin 37 should have battery voltage with the key, not battery+. I still don't get why anyone would wire anything to it, it's supposed to an open position and the signal doesn't tell you anything the ignition relay can't. You'll still probably have a "past" dead-MAF code that might make the car limpy, make sure you clear it.

VStar650CL wrote: ↑

Sat Apr 23, 2022 7:00 pm

altima_slave wrote: ↑

Sat Apr 23, 2022 6:09 pm

I had it on amps, I wanted to see the performance of the circuit I fixed so I turned the seat heaters and checked the amperage and forgot to switch back to volts. Would that have fried the IPDM ? When I press the ignition switch all the accessories come on but don't hear the fuel pump prime the rails and when I press the button + brake no crank

I am replacing the IPDM tom, I found one at JY for 70. So swapping it out should be ok? Pin 37 should have battery voltage right ?

Pin 37 should have battery voltage with the key, not battery+. I still don't get why anyone would wire anything to it.

Do you mean this will.give battery voltage when the key is detected ? I didn't get what you mean by "key, not battery+"

I believe they used this to power the remote starter's reciever that listens for the signal from the RS key fob.

altima_slave wrote: ↑

Sun Apr 24, 2022 6:40 am

Do you mean this will.give battery voltage when the key is detected ? I didn't get what you mean by "key, not battery+"

It shouldn't have 12V all the time, only with the ignition on. It's basically the "on" signal for the Ignition Relay, and the power supply for the coil on the Fuel Pump Relay (the ECM provides ground).

altima_slave wrote: ↑

Sun Apr 24, 2022 6:40 am

I believe they used this to power the remote starter's reciever that listens for the signal from the RS key fob.

I don't think so, it's only hot with the Ignition and the maximum power it can provide is probably a few hundred milliamps. That's why grounding it blew it up. The thing is, it doesn't do anything or provide any signal that couldn't be got by tapping the output of the Ignition Relay. They could have put 12V into it and arbitrarily turned the Ignition Relay on, but that wouldn't power up the ECM or the Fuel Pump. Using it at all, for anything, makes pretty much zero sense.

VStar650CL wrote: ↑

Sun Apr 24, 2022 8:10 am

altima_slave wrote: ↑

Sun Apr 24, 2022 6:40 am

Do you mean this will.give battery voltage when the key is detected ? I didn't get what you mean by "key, not battery+"

It shouldn't have 12V all the time, only with the ignition on. It's basically the "on" signal for the Ignition Relay, and the power supply for the coil on the Fuel Pump Relay (the ECM provides ground).

altima_slave wrote: ↑

Sun Apr 24, 2022 6:40 am

I believe they used this to power the remote starter's reciever that listens for the signal from the RS key fob.

I don't think so, it's only hot with the Ignition and the maximum power it can provide is probably a few hundred milliamps. That's why grounding it blew it up. The thing is, it doesn't do anything or provide any signal that couldn't be got by tapping the output of the Ignition Relay. They could have put 12V into it and arbitrarily turned the Ignition Relay on, but that wouldn't power up the ECM or the Fuel Pump. Using it at all, for anything, makes pretty much zero sense.

Hey man the car is running great again, thanks for all your support and help. I could have saved $75 by being careful but you live and learn.

I put the the new IPDM and plugged the MAF sensor back and the car was good. The check engine light didn't come on but I will buy a cheap OBD2 later on and check for codes. Thanks again!

Happy to help, you're most welcome. Happy motoring!