Battery light on.... with the key out

[Canadian]

Hey guys, I just finished up my engine swap in my 2001.5. Everything worked out great, literally started first crank and ran smooth, idles a little low but I figure I just have to do some relearn procedures. No check engine lights.

I noticed that when I turned the engine off, and turned the key backwards, the battery light popped on, turn the key to where the fuel pump primes, and it goes off and stays off even with the engine running. But if your turn the key back, or even pull it out of the ignition, the battery light remains lit.

I checked battery voltage and it is slightly low, but resting @ 12.1 volts, with the car running its 14.2, so the alternator is working....

Has anyone ever heard of this before? Or does it point to anything? As far as I can tell everything is connected good and tight and in the correct spot, the ONLY thing I had to change wiring wise during this engine swap was I had to solder on a new alternator plug because I destroyed mine removing it. I simply went to the junkyard and cut the plug and pigtail off an older pathfinder with 3.3 (my cars a 3.5L), cut my plug off at the end, and solderred the 3 wires together. The wire colors were the same, and the physical plug was the same and clicked right into my alternator, and my solderring is perfect. Thats the only thing I can think of that would somehow cause this, at the light was not on before the swap, maybe the wires go to different pins on the alternator on the 3.3L? I shouldve confirmed that

Any suggestions where to start?

Edited May 23, 2014 by Canadian

[Canadian]

So I lost some voltage in the battery over the course of the night. So I disconnected the battery, light goes off (i think that might be obvious to some)

 

So then I disconnected the alternator plastic plug connector aswell as the power wire coming off of the alternator output post (secured it away from grounding) and then reconnected the battery, and the battery light is still on in the dash.

The only thing left connected to the alternator is the ground cable held by the small 6mm screw.

 

All wiring I can see looks perfect to, nothing pinched, everything secure, I also took my battery grounds off and gave them a good sanding to shiny metal, light still on.

[Canadian]

I found that if I pull the ALT fuse underhood the light will go off

If I understood how to read a proper wiring diagram I would probably have a clue what that meant

[Canadian]

maybe I do, sc-19 of the FSM states

 

"With the ignition switch in the ON or START position, power is supplied
- through 10A fuse [No. 8, located in the fuse block (J/B)]
- to combination meter terminal 12 for the charge warning lamp.
Ground is supplied to terminal 43 of the combination meter through terminal L of the alternator. With power and ground supplied, the charge warning lamp will illuminate. When the alternator is providing sufficient voltage with the engine running, the ground is opened and the charge warning lamp will go off.
If the charge warning lamp illuminates with the engine running, a fault is indicated."

Does that mean my ignition switch is possibly shorting with the key out? As my light is on with no key even in the ignition"

Edited May 24, 2014 by Canadian

[Slartibartfast]

Congrats on the otherwise successful engine swap! That is weird though, having the light on/key off.

 

I think we can rule out a bad ignition switch, since the light isn't on all the time, only when the key isn't on, and nothing else is coming on with it.

 

I had a similar problem when I re-wired my cargo light to the spare carrier push switch. After I got it all buttoned up, I turned off the key, closed the carrier, and the "tire carrier" idiot light came on. The dash was supposed to be +, and the cargo light hooked to +, and - was supplied to both circuits by the carrier switch, so I was pretty confused as to what was powering that bulb. Apparently the voltage regulator (or something?) in the dash, normally +, went weakly - when the ignition was off, enough to send power through the bulb, into the cargo light circuit I'd hacked into, through that bulb, to the + lead there. (When I finally figured it out, I wired a diode into the idiot light circuit, blocking the backflow and solving the problem.) I bring this up now because it sounds like maybe one of your alty wires is pinched/touching something it shouldn't, and it's somehow feeding current through the idiot light when the dash is off.

 

I think you can rule out the order of the alty pins, since unplugging the alty makes no difference, but that doesn't mean the alty wiring isn't the problem. It sounds like you did the soldering right, but that's still the first place I'd check for shorts. If that's not the issue, maybe that harness got mushed somewhere during the engine installation--squeezed between the alty and the bracket, or up against the firewall, I dunno how that harness routes on the R50.

 

Does the alternator charge the battery with the engine running?

 

If the wiring checks out, at least you know the current is going through the alternator fuse. That might help narrow down the problem. In case the issue's similar to mine, you could pull the fuse and do a voltage check across that fuse hole, key on and off, and see if there's power there with the key off--and if it changes polarity. It's kind of a long shot (and it's based on my assumption that the WD21 carrier light and the R50 battery light have similar wiring) but if you run out of other things to test, it might be worth a shot.