LucisA

I've got an issue with my tail light fuses. They keep blowing. Nothing has been changed before this started happening. I tried to troubleshoot the issue and found that there's two factory ground cables in the engine bay on the passenger side closest to the head light. When I unscrewed them the break lights came on but when I touched them back together the fuse blew again. I kept them detached and found that the right blinker was constantly on but still blinked when the right blinker was engaged.

The break lights would come on when the break was pressed on before I removed the ground cables and still do now but I know this isn't a fix and want to fix this correctly. I will be going out again tonight and try to take voltages from the grounds and see how much power is flowing through the grounds.

also btw, the Fuse that keeps blowing is located at the driver side kick panel

LucisA

So over the last two days I've done some more troubleshooting and found that the ground on the body next to the driver side head light is getting 10 volts continuously. With or without the fuse installed. I then proceeded to un wrap the harness that the grounds ran into and followed it up until the center of the core support and called it a night once the wire turned into three wires. I then decided to check the tail lights thinking that maybe one of the connectors melted. I visually inspected them and they all look good as well as all of the wires through the housing wall up unit the tail light housing itself. I decided to unplug the entire housing and found that the blinker in the head light was no longer constantly on but there was still 10 volts to the ground behind head light.

I will be posting photos next.

LucisA

LucisA

Still no solution to the tail light fuse. Anyone please help.

gerrb

iTrader: (34)

What year is your car ? I assume 95 or 96 judging by you tail light assembly. Is it an SC300 or SC400 ?

Do the front left and right clearance light and markers have bulbs ? Make sure none of those are shorted cause those are grounded to that bolt you were taking out and share same 7.5A TAIL Fuse. So if one of those four is grounded ... the moment you bolt those grounded wire ... the fuse breaks.

LucisA

It is a 96 sc400. All bulbs are accounted for and operational when the ground is disconnected. Yes the moment I connect the ground the fuse blows. But with one of the two grounds removed (the one getting 10v constant) the fuse dose not blow but has the right marker light dimly lit when the lights are on. The moment I remove the right rear light assembly the front right marker shuts off. I didn't check if there was a change in voltage on the ground Unfortunately. I did suspect a bad or shorted light assembly but then I followed the ground wire through the harness up until the center of the core support and found it splitting off until three wires. I stopped there due to the lack of tessa tape to continue down the harness.

gerrb

iTrader: (34)

there should be no 10v on any of the ground points otherwise one of the wires there has a component that probably has failed (shorted by now) thus positive voltage is flowing into it. We know it is not coming from the 7.5 Tail Fuse since 10v is there even without the fuse as you mentioned.

on those two grounds .. which one among them has the 10v and the one you don't bolt back in so as not to trip the 7.5A Tail Fuse ? Need to isolate which one so we know which circuitry to trace and find out where that 10v is coming from.

There are a couple of things connected on those grounds so you need to find out which one has the 10v which should not have and a component in that circuitry might be shorted.

Looking at the diagrams , those two grounds provide the negative (ground) side for the fog lights , side marker , parking light , engine hood courtesy switch , ABS actuator motor ,Cruise Control Magnetic Clutch and front right signal light.

LucisA

could you please share or post that wiring diagram your looking at?! I've been looking EVERYWHERE for one and have had no luck. Also the ground that's receiving 10v is only receiving power when the fuse is in place and the lights are switched on. Not at all times (sorry if my posts dont make sense I've been staying up late after I get off work messing with it then posting half asleep.) As I mentioned in my previous post I followed one of the two ground connections through the harness until I was about half way through the core support. I posted a photo where I stopped with tessa tape. ( once i get more i will be removing all tessa tape again and taking thorough photos and notes. As I follow through the harness some more) but this makes sense about the ground that I removed being a ground for abs and right signal light. My abs light came on shortly after removing (or even when I removed) that ground wire. I will take a few more photos and post it next.

LucisA

in this photo you can see where I cut then soldered two of the ground cables to try and determine witch cable us receiving the 10v power when the headlights are on with a test light and voltmeter. I determined the left wire with the heat shrink was the one receiving the 10v current witch then led me down the harness until I couldn't go on anymore. Now that I know that the ground controls the Abd module as well I am going to remove the 10v ground from that series and then reinstall the other two grounds to prevent any unnecessary damage to other components.

gerrb

iTrader: (34)

check wring diagrams here ... https://www.clublexus.com/forums/per...de-easy-6.html

may not be exactly same as your year but 98% very similar with minor differences since those are pre-96 wiring

I do use the TIS website but you need membership to get into that site.