Hey guys I have a issue that is wierd. The main fuse box in my car is overheating and burning literally. After I drive for a while and the fuse box getnice and hot enough to start smoking then my voltage starts dropping. It gets as low as 8.3 but it doesnt die out I throw it into Neutral and rev it up to maintain the voltage. As long as I am in motion and on the gas pedal than the voltage is fine. But as soon as I get off than the voltage drops. The little battery light on the guages has come on for me. I have had the battery checked and it is good. I went to my mechanic and he said that the main fuse box has to be replaced. The ground on it has burned out. The little screw next to th Alt fuse is where the ground is and that burned. Anyone have any insight or experience with this issue?? My mechanic said that I need a new fuse box. Lexus doesnt sell them they only sell the plastic parts the the fuses go into but no internals. They said that I would have to swap them from the original but How do I do that when my original is f-ed? I would have to purchase one from a junkyard that is my only option. Please someone help. BTW the car is a 2000 Lexus GS400 with 52000 miles.

 

Start by islolating the problem ... which fuse and under what conditions.

Measure current through each fuse. A smart tech with the low voltage range can tell the voltage drop being developed across the fuse box and or fuse. If it has smoked, you should be able to locate melted insulation on wire and trace it.

Either some thing is drawing too much current or some connector is loose in the fuse box. Loose fuse and fuse-end connectors can also be the cause. Also if any fuse was replaced, the new one may not have the right thickness or there could be crud from past.

Salim

 

The problem is that the fuse box has actually melted and changed form a little. I went to a junk yard, they had a crashed gs400 and I purchased a fuse box. I am gonna go to a guy in queens that Gazi from this site recommended and have him run the tests but I dont believe that short of replacing it could much be done with the old one due to how far along the fuse box has melted. This happening on the lex for a lil over a week before I finally found the cause of the problem. Nobody has touched those fuses except me. I only changed the fuse for the headlight cause my ballast blew out causing a short but this was over 1.5 months ago. The fuses that are burning are the big cartridge type, as you are standing in front of the car, they are to the drivers side of the fuse box. Also the little nut attached inside the fuse box and the little piece of metal, i tried to tighten it but there is nothing to tighten to it is actually burned out. It happens whenever it wants, for example on saturday I was driving for 4 hours but with at least 30 minute breaks in between, but today I drove for 20 minutes on the way to the junkyard and it happened but not so drstically I only dropped to 9 volts. This is a screwed up problem to have and I have a feeling that nobody else has had it on here, at least I cant find any threads on it.

 

There are 60amp fuses which support 35amp (guess) normal flow. Once you have a bad connection (0.08 ohms) you get 3v drop and 105watts of heat is produced. All this and no fuse pops.

Before replacing the fuse box, clean the wire terminals also ensure that right rated fuses exist in all fuse boxes. You should disconnect any and all (non oem) electrical devices. If something has been rewired, ensure proper fuse exists ... as close to the junction point (electrically closer to the battery, and farthest from the actual load .. this simple thing protects the shorts in the wiring and not just the oveload).

Good luck and happy hunting.

Salim

 

they only non oem electronics that I have is a system. 2 amps 2 subs and an Pioneer avic n1 but it has been in there for 4 months and nothing has been changed.

 

May be not, BUT

Cars are hostile environment. Vibration and motion rubs the jacketted wires and over time insulation can be compromised .. [BMW owners can comment on this issue].

My suggestion was to start out with stock environment and bring other on line one at a time.

If the stock environement causes problems you will may have to take stock fuses out to narrow down to a perticular malfunctioning circuit.

Salim

 

well I put in the new fuse box and you were right I still have the same problem. I need to try to narrow down what is causing it. I also have some kind of drain on the battery that needs to be located. I am attaching pics of how bad my fuse box got. Excuse the pics they were taken with my phone.

 

Please be aware that there is a potential for fire.

Dumb question: Is the + and - of the battery the right way?

Time to get hold of wiring diagram.

Disconnect alternator and remove ALL fuses in the block you just replaced.
I strongly suspect some thing is shorting before you reach the distribution box (the other fuse box). With this high current I would expect some tell tale signs at the actual problem location. Smell the alternator for burnt out diodes.

One thing that might give you some clue is, does the problem happen after you turn the ignition or even in off position.

Salim

 

that looks bad. I wouldn't drive it like that, you may blow out something very expensive like the ecu. I'd start by disconnecting anything aftermarket. imo, something is loose,shorting out,or drawing too much current.

 

welll I'm going to an audio shop tommorrow in which the guy is an expert in locating shorts and electrical issues like this. BUt I have disconnected the amps and it is not them. I havent yet disconnected the Avic-n1 but I dont think that its it, I've had it installed in 3 of my previous cars and no problems. I will see tommorrow what happens and hopefully they can locate the problem. In the engine bay the only thing that smells is the actual fuse box and nothing else.

 

did o.p. ever find out the problem?