Tail-Light/Plate-Light not working 350GT Skyline / V35 2003

[34Red]

Hi guys I just got my Amplifier and Subwoofer professionally installed using a 2 Channel amp + In line Converter.

 

The Amplifier and Sub works great but after this installation my Tail light/lamp and License light stopped working ! So I can’t take it out at night :0

 

My front head light works and my brake light works when I press on it and reverse light works too.

 

I did some research and heard the tail light and plate light runs through the same wire.

 

I obviously changed the fuses in the engine bay behind the battery (10Amp) but still doesn’t work :S

 

I checked the wires for the in line converter to make sure the guy didn’t forget to plug anything else in but everything is connected and professionally done.

 

Any help would be great, I took it back to the installer and he wasn’t sure what happened himself.

 

I spent hours checking wires and changing many fuses from the interior fuse box and the 2 other fuse box in the engine bay next to the battery but still no luck :S

 

Any suggestions ?

 

 

 

 

 

 

 

[The Max]

Where was the amp installed? In the boot?

[GTSBoy]

Um, start probing at the tail lights and work your way back along that wire until you find power.  The break is thus located.  Probably screwed over by the sub installed by dropping something heavy somewhere.

[34Red]

Where was the amp installed? In the boot?

-The amp is installed in the boot,
-the remote cable is running from the amp and is connected to a Double blade fuse socket to my interior fuse box next to the drivers pedal
-the Red power cable is connected to the battery straight the the Amp.
-My Black ground cable is connected to the amp and to the body and secured tightly.
-My RCA cable is connected to the Amp and going to the Line Out Converter.
-The Line out converter has 4 wires on the other end (L+Green,L-Brown,R+Grey,R-Black)

-The Line out converters wires are connected to the rear left and right speakers.

[The Max]

The installer buggered up something in your boot then. As previously suggested, take your boot apart and work your way from the lights on.

[34Red]

I tried taking off the Wedge connector that’s connected to the Remote cable and tried plugging back the 10amp fuse on its own but still no luck :S

WTH COULD’ve HAPPENED :0

[The Max]

Please pay attention to what we're telling you.

Start looking from your taillights onward. That means looking in your boot space. Stop persisting with your dash and fuseboxes.

[34Red]

Thanks Max

I’ve been looking around the tail lights and check the wiring and they been looking good so far, I moved them around abit in case it was crimped.
All the cables were all visibly intact

I have a itchy feeling maybe the line out converter is drawing out too much power and not putting out enough power for the tail light ? could it be a loose ground cable possibly ? Could it be my sub and amp ? :s

I’ll dig in deeper and let you guys know and thanks for the advice guys !

[The Max]

Wait. You mean the power source for some of your aftermarket audio components is being drawn from the lighting circuit?

Nothing should be intercepting your taillights. They should be left alone and a more suitable power source should be obtained, preferably from the head unit's source instead.

[The Max]

Also, get your hands on a multimeter. Visual inspection alone isn't going to solve this.

[34Red]

The ground wire in the rear seats near the speakers controls all the tail lamp/ license light as refer to the manual book, but when I check out my rear seats I can only see 2 wires coming out and it’s the rear speaker wires which are black and brown on the right side and on the left side it’s black/yellow & green/yellow

And at the moment my Line out converter is connected to both of those rear speaker wires.

Could that be the culprit ?

And my Remote wire is connected onto my Mirror 10amp.

The Red Power cable is from the battery straight to the amp.

I just realise my centre console light isn’t on anymore, everything still works but has no light ...

I’m gonna go buy a multi meter tomorrow !

[34Red]

Also, get your hands on a multimeter. Visual inspection alone isn't going to solve this.

So I checked with a multimeter and tested the tail light fuse next to the battery and it’s working, I checked all other fuses while I was at it.

I tested my plate lights wire at the back and no light so it’s a wire that’s shorting it somewhere.. still boggled

[The Max]

First, forget about your line-level converters. They are a passive device and don't require any power from your vehicle's power circuits. Their job is to reduce the voltage from your speakers down to something friendlier for your amp and no external power is required to make that happen.

Not sure what you mean by testing the plate lights wire and you don't say how.

If you turn on your parking lights, with your multimeter set up to measure DC voltage, you should be seeing 12V at your plate lights. Now, hopefully you're taking the initial measurement by putting the probes on each of the two terminals that feed the plate lights. If you have nothing there, the next thing to check is if the ground is OK or not.

The way to do this is to keep one of the probes on what should be the 12V wire and touch the other probe on a bare metal object nearby, such as a bolt, chassis, reinforcement bar behind the bumper, etc. If you get the 12V reading I described above, that means the light is getting power and the grounding has been buggered up. In which case, you need to trace the ground wire and see where it has been severed or perhaps not even bolted into the body/frame to begin with!

I dare say it's going to be something as simple as that. Judging from what you've mentioned so far about the audio install, your installer probably used the bolt that grounds the lights for your amp and didn't put the lights back under that bolt as well. Take a look at where your amp is physically installed - follow its ground wire and see if there's anything floating around near where it's bolted to your car that looks like it should be actually attached. Confirm it with your multimeter by doing a continuity test, to be sure it's actually going to your lights.

As for a short circuit, trust me, if you say that your fuses are OK, it's not shorting out anything, otherwise you'd be blowing fuses constantly. This is the opposite of a short circuit, or what we call in the business, an air gap.

[34Red]

First, forget about your line-level converters. They are a passive device and don't require any power from your vehicle's power circuits. Their job is to reduce the voltage from your speakers down to something friendlier for your amp and no external power is required to make that happen.
Not sure what you mean by testing the plate lights wire and you don't say how.
If you turn on your parking lights, with your multimeter set up to measure DC voltage, you should be seeing 12V at your plate lights. Now, hopefully you're taking the initial measurement by putting the probes on each of the two terminals that feed the plate lights. If you have nothing there, the next thing to check is if the ground is OK or not.
The way to do this is to keep one of the probes on what should be the 12V wire and touch the other probe on a bare metal object nearby, such as a bolt, chassis, reinforcement bar behind the bumper, etc. If you get the 12V reading I described above, that means the light is getting power and the grounding has been buggered up. In which case, you need to trace the ground wire and see where it has been severed or perhaps not even bolted into the body/frame to begin with!
I dare say it's going to be something as simple as that. Judging from what you've mentioned so far about the audio install, your installer probably used the bolt that grounds the lights for your amp and didn't put the lights back under that bolt as well. Take a look at where your amp is physically installed - follow its ground wire and see if there's anything floating around near where it's bolted to your car that looks like it should be actually attached. Confirm it with your multimeter by doing a continuity test, to be sure it's actually going to your lights.
As for a short circuit, trust me, if you say that your fuses are OK, it's not shorting out anything, otherwise you'd be blowing fuses constantly. This is the opposite of a short circuit, or what we call in the business, an air gap.

Thanks Max I have a feeling it could be a loose ground of some sort too and I test the plate lights where the globe plugs in with a circuit tester to see if it lights up but nothing

The technician said it could be my BCM (Body Control Module) but if it is would the OBD 2 scanner pick this error up just to clarify ? because I don’t want to get a new BCM if that’s not the culprit.

Time for me to check the ground wires throughly again.

Thanks Max you have been so helpful !

[The Max]

Putting two and two together, this only happened after you had an amp installed. The simplest explanation is typically the most likely one.

Whoever told you it was the BCM either isn't aware of the events that led up to this problem or he's taking stabs in the dark.

[34Red]

Putting two and two together, this only happened after you had an amp installed. The simplest explanation is typically the most likely one.

Whoever told you it was the BCM either isn't aware of the events that led up to this problem or he's taking stabs in the dark.

I took it back to the mechanics today and they tested the fuses and made sure all my ground wire was connected properly and it is.

The amp ground cable is bolted in on the original amp holder and there was no loose cable that was hanging around so that clears that out.

The mechanic just bought a spare BCM and other circuit board and is gonna try and replace it to see the difference if it works then I’ll have to reprogram my key and etc.

Hopefully it gets fixed because I need to drive at night time sadly [emoji20]

I’ll keep you all up to date !

Thanks guys

[34Red]

Here’s a photo where I mounted the ground wire for the amp (rear boot)

[34Red]

Hey guys FINALLY FOUND THE PROBLEM !!

The mechanic followed the installation where all the wires were going and found a split wire hanging out, we fixed that up and now it’s all working !!

Well done everyone for helping out! That was a hell of a task !! Tricky car !!

[34Red]

The incident happened when he was putting the power cable through the firewall and he said he must’ve split one of the wires accidentally while pulling it through where the BCM and other fuses were located.

LUCKY LUCKY!

[The Max]

What a spastic installer. That's one guy to avoid in the future.

So few appreciate the amount of care required to be taken before, during and after installations. Even fine details like cable pulling lubricant, self-amalgamating tape and glue heatshrink make all the difference in ensuring not only a reliable installation but also a vehicle that doesn't have its existing reliability compromised.