Defeated by Nissan

"SilentButNotReallyDeadly...killed by G/O Media" (silentbutnotreallydeadly) 10/03/2018 at 07:30 • Filed to: Nissan

0

7

I’ll admit I’m not an auto electrician but I’ve ridden this horse before. More than once. Successfully. But this time...

This time, Nissan got me.

Got in the ute to head back into town just on dusk. Turned on the headlights. And noted that the gauge lights were out. That’s... inconvenient.

Headed to the internet to see if it was a common thing for a Nissan Patrol. Why yes...it is. The gauge lights are included in the tail and park lights circuit. The failure to function is clearly intended to show you that your tail lights are out.

This feature is not included or described in the vehicle operating manual.

Turned out the fuse had blown and I very likely had a dead short in the circuit.

Given I’d recently fitted a bullbar and this included new parking lights on the same circuit...this was the likely area of fault. So I unplugged the front lights, both the factory and bullbar lights.

Still a dead short.

Unplugged the rear lights. Dead short.

Had a little tantrum. Then plugged everything back in.

Started checking wiring under the tray and body of the ute...easy enough when it’s a tipper body.

No burnt bits. No suggestions of any hot smokin’ action.

Returned again to the internet. And of course there was an answer...

There is a component of the tail light circuit that goes to the radio harness. When all power is out, this wire is the only one in the connector block that has continuity with the chassis. In other words, it appears earthed. But it isn’t.

Recently, I installed a new media player. Naturally, I spliced in the media player earth wire to the only wire on the audio connector block that was demonstrably earthed. And it all worked just fine. Apparently...

Until you turn the headlights on. That ‘earth’ wire is actually used to signal to a compatible head unit that the headlights are on so it must be dark and the head unit can dim its lights accordingly. While the headlight switch is off...the wire is earthed. But when it’s on...voltage.

So I’d used it to create a dead short. And blown a few 10 amp fuses as a result.

It’s all very logical in a Japanese kind of way but present it with an enthusiastic but ignorant Australian and logic be damned. Even my vehicularly ambivalent Beloved thought Nissan Logic was a bit dumb...so at least it’s not just me.

The (rhetorical) mystery now is...how was the previous cassette deck actually earthed?

Meanwhile, the new media player now has its own dedicated earth connection and the balance between the Patrol, working tail lights and sweet tunes has been restored.

pip bip - choose Corrour > SilentButNotReallyDeadly...killed by G/O Media 10/03/2018 at 08:14

0

gotta love the Japanese logic

nerd_racing > SilentButNotReallyDeadly...killed by G/O Media 10/03/2018 at 08:20

1

It is quite possible there was a jumper wire to earth from the body of the head unit, or it was earthed by a fastener to the body of the unit. I have seen this in Dodge, Mitsubishi, and Mazda units from time to time.

SilentButNotReallyDeadly...killed by G/O Media > nerd_racing 10/03/2018 at 08:46

0

I’d have thought so but there was no additional wiring nor was the OE deck actually fastened in place...just clips.

Of course, it could still have been earthed via the body , through those clips to the audio unit carrier frame which is connected to the vehicle chassis. Indeed... probably was.

TheTurbochargedSquirrel > SilentButNotReallyDeadly...killed by G/O Media 10/03/2018 at 09:34

0

My guess would be that the factory unit was grounded using the screw it was mounted with.

Thats a pretty nifty way to indicate your lights are out, though it would mean that loosing one light would result in loosing all the lights.

Echo51 > SilentButNotReallyDeadly...killed by G/O Media 10/03/2018 at 09:35

1

The “dim” wire is perfectly normal in the stereo wiring. Didn’t have a wiring diagram handy? Is there really not an actual ground wire? What year/model is said Patrol?

Apparently it is grounded via the metal bracket on the radio? Efficiency!!
source:  https://www.installdr.com/Harnesses/Nissan-Wiring.pdf

SilentButNotReallyDeadly...killed by G/O Media > TheTurbochargedSquirrel 10/03/2018 at 18:24

0

Factory unit had no retaining screws . Clips only.

Oh the logic behind the idea was great...

SilentButNotReallyDeadly...killed by G/O Media > Echo51 10/03/2018 at 18:41

0

Clearly!

Unfortunately, my 2001 Patrol DX cab chassis has a different connection plug. It’s a single 10 pin (two rows of five) with not all pins filled. I suspect it was another efficiency exercise by Nissan.

I was able to use the OE cassette deck to identify the factory wires but was mystified by the lack of earth lead connection to the deck despite there being an input for it . Inexperience led me to my fateful decision to make the wire selection I did...

I have an adaptor harness that would suit the later version in that pdf...but not what I have.