Help Needed Please,electrical Faults!

[Straight-Six]

Hi everyone and thanks for taking the time to look at this topic.

I'll summarise the problems briefly then explain futher as its a long story.Right now my Lexus IS200SE 1999(auto) is suffering from the following.

1.When you turn on the heated rear screen the following happens,the green 'd' on the instrument cluster 'clicks' on and off intermittently,and the temp dial on the instrument cluster dives to cold for that period of time,then,all goes back to normal.This happens usually after a 5-10 minute drive when the car seems to have got up to temp.

2.The rear parking sensors work normally when approaching an object,however,upon selecting reverse there is another constant tone above the usual beeping noises.This isn't always happening but most of the time.

3.The headlights turn on when the ignition is turned off and the drivers door is opened and wont turn off unless the fuse is removed.

I have had the car to Lexus Newcastle twice to fix the various problems,they managed to fix the climate system(this was blowing very cold or very hot) by replacing the system at a cost of £710,and the Alarm system was going off for no reason and the central locking wasn't working(keys reprogrammed,battery top up etc at a cost of £73.All the above problems,with the exception of the head lights,all happened at the same time approx 2 months ago.I have also taken the car to a very highly recommended Auto Electrician in Newcastle who had the car for 3 days and couldn't diagnose the faults.The final straw was the headlight problem which happened 2 weeks ago.Since then the car has spent the last 10 days with another highly recommended AutoElectrician who can't diagnose the problem so we have agreed that he has one last go at it tommorrow and then i must explore the possibility of selling the car with the faults,which i really don't want to do as i love it to bits.

So people,you are my final hope that someone may know what is happening to the car:crybaby:

Heres hoping!!!

Thanks,Justin ;)

[nicnac]

Hi Justin

Is there any possibility that a wiring loom has been damaged ? maybe on a past repair and is now corroding etc....the reason i say this is that all the faults seem disjointed!

Has anything been welded on in the cars life ?I have seen this in the past where a sill repair had partially melted the witing loom and weird faults croped up 2 years later.

just a thought!!

Oh or water corroding your fuse box/boxes due to a bad repair?

[Straight-Six]

Hi Justin

Is there any possibility that a wiring loom has been damaged ? maybe on a past repair and is now corroding etc....the reason i say this is that all the faults seem disjointed!

Has anything been welded on in the cars life ?I have seen this in the past where a sill repair had partially melted the witing loom and weird faults croped up 2 years later.

just a thought!!

Oh or water corroding your fuse box/boxes due to a bad repair?

Thanks for the reply mate

Lexus's initial thought was that it was water getting in to a fuse box as they knew there was a fault on the early 1999 IS200 this happened to where the water came in through a corroded seal in the base of the windscreen but they couldn't find anything.Also today after speaking to the current AutoElectrician looking at my car he has said he has checked the wiring everywhere and can't find a fault.

He is going to try and disconnect the rear heated windscreen function tommorrow to see what happens...were clutching at straws now i think.I can handle the dash faults but im not going under the bonnet and pulling a fuse everytime i want my lights to turn off!

Its very disheartening.When i asked Lexus about it they admitted they didn't have a clue how to repair it as they just don't have these types of faults.

[nicnac]

ask your electrician to use an insulation tester(safety type) on your cable looms .If he has a wiring diagram he should try and find the light staying on fault first as ovbiously a relay is being energised by some + supply .(cable loom leak).

if he goes down this road he should disconnect the ECU before doing any meggar tests.we dont want any thing worse to happen.

Its a pity i dont live in uk or i would be happy to sus it out

another possibility is bad earthing ...he should be able to see this

[Straight-Six]

ask your electrician to use an insulation tester(safety type) on your cable looms .If he has a wiring diagram he should try and find the light staying on fault first as ovbiously a relay is being energised by some + supply .(cable loom leak).

if he goes down this road he should disconnect the ECU before doing any meggar tests.we dont want any thing worse to happen.

Its a pity i dont live in uk or i would be happy to sus it out

another possibility is bad earthing ...he should be able to see this

Thanks again,i am going back for the car tommorrow afternoon so i can ask if he has tried this yet(in a non patronising way!!)

Your help is most appreciated mate

[Monster-Mat]

has the car had a new windscreen at any point.

i suspect there is water getting into the right hand fuse box, also hence the headlight issue

ask your electrician to use an insulation tester(safety type) on your cable looms .If he has a wiring diagram he should try and find the light staying on fault first as ovbiously a relay is being energised by some + supply .(cable loom leak).

if he goes down this road he should disconnect the ECU before doing any meggar tests.we dont want any thing worse to happen.

Its a pity i dont live in uk or i would be happy to sus it out

another possibility is bad earthing ...he should be able to see this

its not so easy to find cluster faults as it is connected into the multiplex system, meaning single wires carry multiple signals

Edited March 16, 2006 by Monster-Mat

[nicnac]

@MM

Have never had the need to look at the wiring system on the Lex and to see if they use a common bus type of communication but it should be fairly straight forward for a competent electrical/electronic engineer armed with a circuit diagram a multimeter and a half decent oscilloscope .

[Monster-Mat]

@MM

Have never had the need to look at the wiring system on the Lex and to see if they use a common bus type of communication but it should be fairly straight forward for a competent electrical/electronic engineer armed with a circuit diagram a multimeter and a half decent oscilloscope .

oh i agree....unfortunatly my book is being used elsewhere.

i still suspect a fuse box issue.......

[Straight-Six]

has the car had a new windscreen at any point.

i suspect there is water getting into the right hand fuse box, also hence the headlight issue

ask your electrician to use an insulation tester(safety type) on your cable looms .If he has a wiring diagram he should try and find the light staying on fault first as ovbiously a relay is being energised by some + supply .(cable loom leak).

if he goes down this road he should disconnect the ECU before doing any meggar tests.we dont want any thing worse to happen.

Its a pity i dont live in uk or i would be happy to sus it out

another possibility is bad earthing ...he should be able to see this

its not so easy to find cluster faults as it is connected into the multiplex system, meaning single wires carry multiple signals

Im pretty certain the windscreen hasn't been replaced,Lexus did say they had checked this "known fault" with the windscreen and found nothing wrong.

[nicnac]

@mm

It does sound like corrosion around a common sorce or dodgy earth connections which are allowing floating voltages to be present.thats why i wondered if body repairs have been carried out which could allow such moisture ingress.

the fuse boxes would need to be physically inspected at their rear for any corrosion signs.

in a past life I saw a lot of terminal block corrosion caused by salt water on Nimrod aircraft and its possible for multi confusing symtoms to occur.

its one case where you need to get in and at it!!!!

[Monster-Mat]

@mm

It does sound like corrosion

yep...thats what im thinking

the fuse boxes would need to be physically inspected at their rear for any corrosion signs.

yep, there located in a hollow in the A pillar, this iw where the water collects and dmagaes the open back of the fuse box and relay boards

in a past life I saw a lot of terminal block corrosion caused by salt water on Nimrod aircraft and its possible for multi confusing symtoms to occur.

its one case where you need to get in and at it!!!!

ah Nimrods....such a fine aircraft

[nicnac]

@mm

ah Nimrods....such a fine aircraft.................yep i alaways felt safe in them but i knew how well they were serviced.thats why i dont fly if i can help it...i dont trust comercial carriers where the buck means everything!!...im a bit of a dinasoar really

[NetOne]

The problem may be related to one of the following issues...

1 - Look very hard for any corrosion on the metal part that cause bad earth.

2 - Water got in the wiring system or fuse box that cooked some of the relay or electric component.

3 - The On/Off switch stick might be faulty. It sounds silly but possible

[Straight-Six]

The problem may be related to one of the following issues...

1 - Look very hard for any corrosion on the metal part that cause bad earth.

2 - Water got in the wiring system or fuse box that cooked some of the relay or electric component.

3 - The On/Off switch stick might be faulty. It sounds silly but possible

Thanks for the help everyone.Something else worth mentioning is the timing of the temp.dial dropping and drive light cutting out,it almost feels like its the element of the rear heated windscreen kicking in for ..say 5 seconds,and causing the power to drain from these othe parts.You can physically hear a clicking noise coming from below and to the right of the steering wheel when this happens.However i have no explanation to the headlights turning on when the ignition is turned offAND the drivers door is opened.I always tend to leave the lights switched on auto and what happens is the exact opposite to what would normally happen...strange :duh: