92 Ls400 Reverse Light Never Goes Out. Please Help!

[Drparj]

Have a 92 LS400 that has a reverse light issue. It never goes out and thus is not able to be driven due to the transmission not wanting to shift out of 1st gear. As soon as you turn on the car the reverse dash light and reverse lights themselves are on and stay on no matter what position the shifter is in. The wife said it actually use to not come on and she had to wiggle the handle while in reverse to get the lights to come on and now it just stays on. Now the car is not able to be driven due to it being on all the time.

I have looked in trunk and found no shorted wires.

Is there a switch somewhere in center console that tells car when it is in reverse? I can't seem to find one. I did find a shift control computer? Does that have anything to do with it?

Lost with all the electrical here and need of help.

Thanks

[Drparj]

I think maybe its the reverse switch, does anyone know where to find this on car so I can check it, do I have to remove entire shifter or get under car?

[Lucky13]

Seems like a transmition prob. Not an electrical one.

[Drparj]

It has all the same issues as the hinge short problem its just not shorted there. A short in the wire somewhere else would cause same problem and a bad switch at the console might cause the same problem. If switch is bad and thinks it is in Reverse all the time then problem solved, but I can't check until I find where the damn switch is. Any idea?

[1990LS400]

Did you completely unwrap the wires in the left trunk hinge and separate them to check them closely. Even if the insulation isn't broken or cracked, a wire can still be broken inside the insulation. Check the hinge wires again and wiggle each wire to see if is broken inside the insulation.

This is sounding like the exact same problem that first bought me to this forum in 2003.

[jcrome04]

+1 Trunk wire harness

[eatingupblacktop]

It has all the same issues as the hinge short problem its just not shorted there. A short in the wire somewhere else would cause same problem and a bad switch at the console might cause the same problem. If switch is bad and thinks it is in Reverse all the time then problem solved, but I can't check until I find where the damn switch is. Any idea?

It's actually not a short but an open circuit. As 1990 suggests, unwrap the insulation and examine a bit closer.

[Drparj]

I did look at wires and they look new, not decayed, but I will I guess check bends and cut wire myself. I did find neutral switch on side of tranny and unplug harness and lights went out, but could not start car due to computer not knowing if its in park or neutral.

But the open circuit confuses me. All other people had to turn there lights on to have this issue.

I do not.

The dash still indicates what gear I am in and at same time keeps R lit up. SO it shows both park and R, D and R and so on. Would this still possible be the hinge issue?

[Drparj]

what wire at hinge is usually the culprit of this (white)? I think I heard before.

And could this be caused by the neutral safety switch going bad?

Showing correct gear and R at same time?

Anyone have a wiring or color code for wires coming from the Neutral safety switch?

[jcrome04]

http://www.lexls.com/tutorials/lighting/bulbout.html

[Drparj]

I found that link before and it just tells a lamon what to do. I know how to do all that. I don't see how that would cause my problem though.

This does not happen when the lights are on or I step on the brake. It is all the time. No matter what is done.

I checked all the wires and wiggled every part in truck and nothing still.

I do know the white wire is the ground wire, thus if it had a break it would be a ground fault.

The red wire is the backup lights

And the yellow and green are blinkers.

The more I dive the more I think its the safety switch or the wire might have a break but somewhere other then hinge. I think my safest bet is to trace where the harness leads to leaving the neutral safety switch on the tranny.

Anyone know that answer?

[1990LS400]

The hinge wire that caused the problem on my 90 LS back in 2003 was the "white with black stripe" wire: http://us.lexusownersclub.com/forums/index...94&hl=hinge

Have the trunk hinge wires been previously repaired? I sold my 90 LS in 2003 and its current owner told me that he has had to repair the hinge wires again -- they just keep breaking.

If your hinge wires have never been repaired (new wires spliced in), there is an extremely high probability that this is the problem. Few gen 1 LS400's make it very far past 10 years without the trunk hinge wires breaking.

Be sure to carefully check all the wires. Many people find multiple wires broken -- even when the insullation is completely intact.

[Drparj]

I understand this what I dont't understand is how it could cause my problem.

Everyone else with this problem either has to turn on lights or apply breaks.

I do neither

It is on as soon as I turn key.

Also if there was a break in the wire I would not get continuity through it and I am, tested with a volt meter.

SO at that I think its not wires but the neutral safety switch.

[1990LS400]

Also if there was a break in the wire I would not get continuity through it and I am, tested with a volt meter.

Because continuity does not = adequate or consistent voltage .... the wires separate and rejoin enough so that current is intermittently transmitted through the wire.

[Drparj]

How would a break in a ground wire cause this problem? I'm not new to working on cars but new to working on a Lexus.

If the white had a break the back up lights should not illuminate due to no ground but they do. If any one of the wires had a break something would not work but they do.

And again to the point that this does not happen when I stop on brakes or turn on lights thus powering the taillights and causing the R to illuminate.

This happens when no power at all is going to the taillights which would eliminate the problem being in the hinge. There is no constant power going to the tail and thus no way a broken wire could cause a problem like this.

I see it happening with the other scenarios but not mine it just makes no sense

[jcrome04]

If you don't want our advice don't ask for it.

Much useful info has been given and you're just shooting it down.

You need to go out to your car and expose ALL the wires. NOT just a couple you feel necessary.

Don't ask for advice if you won't take it please.

[Drparj]

OMG so far no one on here has listened!!!

I exposed all wires and all wires are fine, nothing wrong. 100% working and not broken. How do I make that any clearer. That is not the problem and all anyone wants to say is it is the hinge wires. It may be the most common problem but it is not mine

[Drparj]

Simple wiring

Open circuit means a wire can be cut and everything will function fine til that circuit is powered. Then nothing goes through

A closed circuit is usually constant with power (no switch) thus closed and if broken it will immediately cause a problem.

Thus when the lights or brake lights come on with this problem then yes it will happen with an open circuit which is what the lexus has.

My problem could only be occuring in a closed circuit if none of the above effects have been introduced.

So either I have a break somewhere else in the wire coming in contact with something or the neutral safety switch is bad.

I have already pulled the neutral switch and tested it, but without the proper wiring diagrham I don't know if that is indeed the fault or I should search for another broken wire.

I also do not know where the harness goes to from the neutral safety switch as it is above the tranny and extremely hard to trace unless tranny is lowered.

Does this make sense to everyone yet.

Getting frustrated as I have been out to the car with every suggestion and it has led me knowwhere.

[eatingupblacktop]

Simple wiring

Open circuit means a wire can be cut and everything will function fine til that circuit is powered. Then nothing goes through

A closed circuit is usually constant with power (no switch) thus closed and if broken it will immediately cause a problem.

Thus when the lights or brake lights come on with this problem then yes it will happen with an open circuit which is what the lexus has.

My problem could only be occuring in a closed circuit if none of the above effects have been introduced.

So either I have a break somewhere else in the wire coming in contact with something or the neutral safety switch is bad.

I have already pulled the neutral switch and tested it, but without the proper wiring diagrham I don't know if that is indeed the fault or I should search for another broken wire.

I also do not know where the harness goes to from the neutral safety switch as it is above the tranny and extremely hard to trace unless tranny is lowered.

Does this make sense to everyone yet.

Getting frustrated as I have been out to the car with every suggestion and it has led me knowwhere.

If the trunk harness checks out, then yes, your probs could be:

- neutral start sw shorting and sending the R position signal to to the combination meter

from every position

- short in the combination meter circuit board lighting up the R position

- the dsl solenoid not functioning properly

Here's the only diags I've got:

For more check out alldata.com

You also mention that your wife played around with the shift lever. Might check the connections there as well.

Oh yeah, and welcome to the club!

[Drparj]

OMG eatingup thank you, just what I was looking for.

I did test the safety switch myself and for some reason it shows the reverse terminal having output with the positive input on every position. I do not see how the switch could actually break but I think that is the problem. I took the whole switch apart and insides look fine but the continuity between the pins seems messed up.

Basically everywhere the positive input is present the reverse output is somehow also present and vice versa. Not sure again how this would happen as I can't see the pins since the back side is coated in a hard resin.

But $140 will hopefully fix this problem.

Thanks again

[Drparj]

And she didn't play with it, just giggled handle to make reverse lights go on, thus leads me to believe the switch was going. I did not know that was happening til all this happened of course.

[1990LS400]

OMG so far no one on here has listened!!!

I exposed all wires and all wires are fine, nothing wrong. 100% working and not broken. How do I make that any clearer. That is not the problem and all anyone wants to say is it is the hinge wires. It may be the most common problem but it is not mine

Good! I was just trying to make sure that you really, really took a close look at the hinge wires. Countless people have taken more than one inspection of the hinge wires to find broken ones.

You did not answer my question ... have the trunk hinge wires been fixed in the past? You should be able to tell. The reason I ask is that about 0% of gen 1 LS400's make it to 17 years without the hinge broken wire problem arising.

[Drparj]

they all look original and they still look new. The looms, tape all still there and factory. I even lightly stripped the wires at the ends and bypassed them and nothing thus I know its not them.

I did take out neutral safety switch and it seems to be somehow combining the positive in and the Reverse out wires inside the switch itself. I took the switch apart and all the brass is fine so it must be in the hard resin somewhere that is having an issue. Something I can't fix and have to replace.

Hopefully this $145 part will solve the problem.

Oh and to make matters worse the dame shift rod nut snapped off while taking out the switch so now I have to weld a new bolt onto the end to keep the shift rod attached.

Foreign cars are not made to be simple I tell you that.

[90LS400Lexus]

1990 - Sounds like the trunk hinge wires were original, untouched until today. :) I guess that was the only and last LS400 that still had the original untouched trunk hinge wires. Unusual that they were all still original and excellent. Hopefully todays tampering didnt cause any damage that may cause future issues. I never closely checked my old 1990 LS400 to see if it had been worked on because I never had any issues, but I am sure it had been at one time? It didnt appear to have been done though... if so, it was professionally. Does anyone have photos of an original, untampered trunk hinge wiring loom on a 1990-94 LS400?

Yeah Drparj - alot of problems crop up because of these trunk hinge wires, so I think thats why everyone was emphasizing on them. Apprarently the wiring gets all twisted and frazzled and causes an array of electrical woes. I dont think anyone was clear that you had completely checked all of the wires and no one meant anything bad by it. You will find there are alot of knowledgeable guys/gals on this site that will be able to offer alot of helpful info. I know that problems on these cars can sometimes be frustrating and hard to track down. I was having a "smoke from the engine" problem with my car that I thought was electrical and was told it would be trunk hinge related, but I think my trunk wires have already been tampered with at some point, so I didnt think that was the problem. I was frustrated, but found out the smoke is from a valve cover oil leak. <_<

I dont have any electrical issues, so I guess all is well, but from the looks of my trunk hinge wiring on my current 1991 LS400 (photo below) it looks to have been poorly done, but since all is well, I am fine with it. At any rate, I hope that part fixes your car properly. Good luck and keep us posted! , but s

OMG so far no one on here has listened!!!

I exposed all wires and all wires are fine, nothing wrong. 100% working and not broken. How do I make that any clearer. That is not the problem and all anyone wants to say is it is the hinge wires. It may be the most common problem but it is not mine

Good! I was just trying to make sure that you really, really took a close look at the hinge wires. Countless people have taken more than one inspection of the hinge wires to find broken ones.

You did not answer my question ... have the trunk hinge wires been fixed in the past? You should be able to tell. The reason I ask is that about 0% of gen 1 LS400's make it to 17 years without the hinge broken wire problem arising.

they all look original and they still look new. The looms, tape all still there and factory. I even lightly stripped the wires at the ends and bypassed them and nothing thus I know its not them.

[Drparj]

Yeah those are def changed on yours, mine where clean with no zip ties and fully hidden.