1992 LS400 Interior Lighting Issues

[Spartan0536]

Hello, I picked up my 1992 Lexus LS400 from my mechanic today after he replaced the Alternator which died, and I had him look at the belt to see if it even had cracks in it, he said it looked like it had been changed a year ago and has less than 1,000 miles on it, so no need to replace. The alternator is of course a remanufactured one as I have been unable to find new production ones. The power steering is all good, with no leaking or signs there of as well.

After picking up the car, I noticed that it did not seem to have the power I have seen on youtube videos and when I test drove it where when you romp the gas that V8 will put you into the seat. But I figured that could easily be me getting used to a manual cable throttle as I am used to an electronic throttle that my 2002 Dodge Stratus used. Fast forward a few hours and I am checking the car again top to bottom for any nagging little things and I come across 3...

1. The remote unlock works and it works quite well, but it will randomly lock the car when the doors are open, perhaps the pressure sensor on the key is getting worn out and is becoming too sensitive?

2. The dome light works, but with all the doors closed it stays on, even if I have it set to door mode, so for now I have to leave it in OFF mode.

3. The passenger floor light (where your feet are when sitting down) will not turn off at all, I have the rest of the car "cold and dark" and yet that damn light is still on, is this supposed to happen, is there a switch I do not know about that turns it off?

WTF is going on here faulty/stuck door sensors? Wiring harness issues? I do not remember any of these being issues and I drove the car during the day and the night, any and all help is appreciated.

[CELSI0R]

It sounds like one of your door sensors is worn out, which are also referred to as courtesy switches. Since the car mainly had just a driver, it would make sense for the driver's door switch to be worn out a lot more than the others. This also makes sense, because you stated the lower courtesy light on the driver's side stays on when closed.

As a safety and security feature, the doors will automatically lock themselves when it thinks a door is being opened and the car is running. I do not think there is a problem with the keyless entry.

Open the doors individually, and try depressing the rubber buttons for each switch . See what happens with the interior lights. Every time you depress the button, the corresponding lights should dim and turn off. If this does not happen, you probably have found the faulty sensor.

Here are some useful references for you:
Door Sensor Issue
LexLS - Front Courtesy Switch Replacement Tutorial

Hope this helps you solve this problem.

Side note: I still have the fob key for my car as well, but I never use it. According to the owner's manual, it's only useful within 3 feet of the car and the fob switch must always be on, which wastes power. I leave this switch off and just unlock the doors with the master key to prevent any additional battery drain. The fob keys can also become brittle with time and break. This will not lead to any problems with the key itself, other than the button being unusable or missing.

[Spartan0536]

Update:

Started the car this morning, A/C controls DEAD, clock still works but the A/C system is non-responsive. Also this car seems to be accelerating very slow. I pushed my foot ALL the way down, and going from 0-60 took 12 seconds. The RPM gauge moved pretty sluggish for a 4.0L V8, it was not like this before I had the car serviced. I took it back the the mechanic, this car is costing me $$$ real fricking quick.

[CELSI0R]

I have no idea what would cause these exact symptoms, but perhaps check the trunk wiring harness on the driver's side (?).

Also, what was the last job performed on the car, before this occurred? 0-60 should take approximately 8 seconds in normal ECT mode (depending on the weight of your LS.. Higher optioned models could potentially take between 8-9 seconds).

It's good to learn how to do some DIY maintenance on these cars. It will save you a ton in repair costs.. Especially if the starter ever goes out.

[Spartan0536]

The work done by the mechanic was the following...

Replace the Alternator with a reman one (unknown what brand, will check, it has a warranty)

Flush and refill the Power Steering and Transmission

Refill the freon in the A/C and put dye in to determine if/where the leak may be

Full 4 point inspection (nothing else turned up according to the mechanic).

Prior to the work being done, the only issues I found with the car were no working A/C (control unit was functional, but no freon was in the system), and there was a high pitched whine when driving the car at slow speeds. The mechanic said that it was the alternator as the bearings were going out, then he said the next day it just died.

 

I took the car home from the mechanic for 1 day, exactly 1 day (24 hours), within that time I noticed the foot light on the passenger side would not turn off (drivers side is INOP, bulb is likely dead). The dome light when set to door will not turn off when the doors are closed (might require a new pressure sensor), and then the next morning the A/C controls were dead but the clock still functions perfectly.

On the drive over, I set the mode to PWR (Power) and noticed a 0-60 time of 8 seconds (calculated using my phones stopwatch feature), this is not what I felt before when I first test drove the car, it was pretty damn quick. I also noticed that the D light in the instrument cluster was SLIGHTLY dimming and then brightening again, it was minimal but you can clearly see it.

 

I am starting to wonder if this car is really worth my time or not, even at 84K miles.

[Spartan0536]

Update:

My mechanic looked at it (for free, which I am grateful for), he tested the wiring to the Climate Control system and it checked out ok, the control unit itself failed however, and it was not the LCD screen, the PCB (mainboard) is shot it looks like. The only thing that functions is the clock and the buttons associated with the clock. My mechanic left the climate control unit removed upon my request and I will be sending it out to Tanin Auto Electronix and yes I will be having its color customized, the LCD will be a Cool White color, the button highlights will be a Bright White, and the LED indicators will be red, something you would likely see in a modern luxury car, it will cost me $60 more but hey I get a repaired unit that works, with a lifetime warranty, and its unique but still stock.

 

As for the other lighting issues my mechanic found the cause after some testing and looking over the wiring schematics of the car, they found the cause to be a faulty relay that sits behind the dashboard, total cost to repair will be $360 and that is including parts, labor, and tax, the replacement will be a new production Toyota relay. As it turns out many of the interior and some of the exterior lights go through that relay, so this may actually fix all of my lighting issues.

 

As for the acceleration issue, I have noticed something and perhaps someone here can explain this to me...

I am under the impression that standard idle should be at 600-650 RPM, is this in park or in drive? The reason I ask is that while in Drive my RPM's are at 250, yes I mean 250, its LOW, but its not stuttering or stalling, its silky smooth.

I also noticed that if I just "gun" the throttle the car does not respond with a "kick in the !Removed!", it instead accelerates at a slightly faster than normal pace, but if I push about 60% into the throttle I get a better response from the engine and as it continues into the higher RPM's I can depress the accelerator for more power (this was all done in ECT-PWR mode). Again I am wondering if this is normal or if I need to prepare to put in some new NGK Iridium IX plugs and some new wires to get better fuel burn?

I am coming from an electronic throttle (2002 Dodge Stratus) to a mechanical wire based throttle, and its been some time since I have driven a car with a mechanical throttle, thoughts?

[CELSI0R]

Good to hear you're gettting the climate control circuit fixed and the interior light issue.

Have you given the door switches a try, too? I'm sure your mechanic tested them, but it would be much cheaper to just replace one of those, if that's the culprit. Some of those relays are a pain to access...

Regarding acceleration, I've never driven an electronic throttle car, so I can't really answer for pedal feel in comparison to other experiences. Your description seems about normal though; this car is heavy, so acceleration time seems to vary within a certain margin. When the cluster is off, does your tachometer needle look like this?



If your tachometer needle rests below the 0 marker when the car is off, it will lead to inaccurate readings. The idle should be around 650 rpm, but my car also reads around 200 rpm because my needle has popped out of place. I need to remove my cluster again to carefully pop it back in place... There's a procedure on this forum that I've reposted to fix that. I can find it again.

EDIT: Here is my old post.

[Spartan0536]

3 hours ago, CELSI0R said:

Good to hear you're gettting the climate control circuit fixed and the interior light issue.

Have you given the door switches a try, too? I'm sure your mechanic tested them, but it would be much cheaper to just replace one of those, if that's the culprit. Some of those relays are a pain to access...

Regarding acceleration, I've never driven an electronic throttle car, so I can't really answer for pedal feel in comparison to other experiences. Your description seems about normal though; this car is heavy, so acceleration time seems to vary within a certain margin. When the cluster is off, does your tachometer needle look like this?



If your tachometer needle rests below the 0 marker when the car is off, it will lead to inaccurate readings. The idle should be around 650 rpm, but my car also reads around 200 rpm because my needle has popped out of place. I need to remove my cluster again to carefully pop it back in place... There's a procedure on this forum that I've reposted to fix that. I can find it again.

EDIT: Here is my old post.

I will be attaching pictures to this post when I get home, however...

When the engine is off the needle sits SLIGHTLY (1/10 of an inch) below the 0, when I am in PARK its idling around 650-700 RPM, and when I am in drive it idles at around 300.

Addendum: My Odometer stopped working at 87,350, I am going to be sending it out to Tanin Auto Electronix as well, but I am wondering if the gauges are lit by bulbs or other electronic means. The reason I ask is that I could replace the stock bulbs with Philips Crystal Vision Ultra bulbs to give them a whiter, brighter light.

Also when using LED lights on the interior and parking lights, does that mess with the computer regarding voltages that might cause issues? I will NOT be using LED's for my brake, stop, turn, corner, or reverse lights.

[CELSI0R]

The odometer is definitely something that you want to keep synced with the car. Might as well have Tanin fix any and all problems with the cluster, since you're sending it to them.

I don't believe modifying the cluster lights will affect anything; however, some lights cannot be changed. Tanin will definitely know what can and cannot be done. LexLS details this on his website.

I have seen LED light mods for the interior and parking lights as well and have not heard of any negative side-effects, so it should be ok. The signals and brake lights are where problems usually occur.

[Spartan0536]

1 hour ago, CELSI0R said:

The odometer is definitely something that you want to keep synced with the car. Might as well have Tanin fix any and all problems with the cluster, since you're sending it to them.

I don't believe modifying the cluster lights will affect anything; however, some lights cannot be changed. Tanin will definitely know what can and cannot be done. LexLS details this on his website.

I have seen LED light mods for the interior and parking lights as well and have not heard of any negative side-effects, so it should be ok. The signals and brake lights are where problems usually occur.

I do not want LED's on the instrument cluster, just a bulb replacement with the Xenon infused bulbs for a whiter brighter light, they usually last about 8-10 years which is about how long I intend to keep the car if parts don't keep falling off of this infernal machine....

On a more serious note, the engine and transmission seem to be in excellent condition and are silky smooth when operating, especially with Overdrive on and ECT on Normal.

ALL and I do mean ALL of my current issues are electrical, and its beginning to annoy the crap out of me

[CELSI0R]

Sorry, I misunderstood. I don't know how those will differ, but I'm sure the Xenon bulbs will be fine. However, I would still not replace any of the bulbs listed on LexLS that could have negative effects on the cluster's performance.

The electrical problems you're experiencing have come up due to wear and tear from the previous owner over the past 25 years. Even though it's a little tedious now, it will pay off in the long run. I went through similar repairs when I got my car 7 years ago, but all have been resolved and have not acted up since.

As a cheaper alternative for the climate control, you could buy a working used unit online. A few are on Ebay. The faceplate and buttons can be swapped carefully, if you want to match the original pieces together.

[Spartan0536]

15 hours ago, CELSI0R said:

Sorry, I misunderstood. I don't know how those will differ, but I'm sure the Xenon bulbs will be fine. However, I would still not replace any of the bulbs listed on LexLS that could have negative effects on the cluster's performance.

The electrical problems you're experiencing have come up due to wear and tear from the previous owner over the past 25 years. Even though it's a little tedious now, it will pay off in the long run. I went through similar repairs when I got my car 7 years ago, but all have been resolved and have not acted up since.

As a cheaper alternative for the climate control, you could buy a working used unit online. A few are on Ebay. The faceplate and buttons can be swapped carefully, if you want to match the original pieces together.

 

So here is the latest....

I talked with my mechanic today, his parts supplier failed him on obtaining the required integration relay... from what I can gather, this relay is responsible for certain electronics within the cabin, but I do not have a full wiring diagram or chilton/haynes manual covering this. I found the part within 4 minutes of searching on Google at a Lexus of South Atlanta for $175, if the diagrams they have on their website associated with the part are any indication I could do the repair myself as it's a bolt on and not a soldering job (I can professionally solder, I am a certified PC technician, and I have soldered electronic parts before, I just hate doing it).

The instrument cluster - I will be waiting a few weeks for this to be fixed, all lights are currently working, the needles are a little low on the RPM side but still functional. Right now my focus is getting that A/C working again, so I have to send the control unit out to Tanin for overhaul/repair & upgrade.

A/C Control Unit - yep it's dead, mechanic stated they tested the connecting wires and they carry the correct charge, so the unit is done. I will be sending it out to Tanin, if they can not repair it, I will sell them the core and use that to offset the cost. They will then send me a remanufactured model for my year with the backlighting (White) and LED (Red) upgrades I requested to make it look more modern.

Entertainment Upgrade - Coming soon, but I have settled on the Kenwood eXcelon DDX594 double din receiver/monitor unit. My cars antenna is shot but I already have the replacement unit which will be installed and it features a thicker gauge shielded & braided wire which should help filter out EM noise. The stock speakers are shot aside from the Subwoofer which is staying and I will have the stock AMP wired to the new head unit via one of the pre-amp's. I think I am going with the JBL GT7-5C component rigs for the front and GTO429 coaxials in the rear, I was thinking of adding in a amp for the speakers but from what I have been told the receiver I am using meets the requirements as long as I do not crank the volume past 80% otherwise I will get massive distortion, and I am NOT going for loudness, I am going for QUALITY. I know its not going to match Mark Levinson 19 speaker rigs in modern Lexus's, but it will outperform 75% of the cars on the road today, and that is what I want. I am considering Dynamat Extreme on the doors and surrounding the rear subwoofer, this should help with road noise (of which the car is already fantastic at negating), couple this with good tires and it should be a wonderful ride.

Suspension Upgrade - Right off the bat I will be installing 2 strut tower braces (1 front, 1 rear), this will help with body roll, which the LS400 is notorious for. If the braces do not remove enough of the body roll I may opt for performance sway bars that will be installed and setup professionally. I love the way my fathers 2013 Mercedes Benz C300 handles corners, not much body roll, I want my car to handle SIMILAR, and I believe the front and rear tower braces will suffice, plus they are a cheap upgrade.

Tires - I am sold on the Cooper CS5 Ultra Touring tires, the research data looks very promising and they are sold at Walmart for $85 a piece. I will have my local tire shop install them, and I will have a balance and rotation done with the install like any sane person would.

Lighting - My headlights & Fog lights are only going to be bulb replacements, I am not interested in wiring in custom HID's. The bulbs I have chosen are both made by Hella, they are the Optilux Extreme White XB's. I currently have Philips Crystal Vision Ultras installed in the headlights, and I am NOT impressed, by old Silverstar ZXE's seemed better in my old 2002 Stratus. From what I have read and seen, the Hella bulbs are brighter than both the Philips and Sylvanias, but they are not "street legal"/DOT approved. However their color is 4300K which is DOT and OEM approved (most OEM projector lamps are using 4300K temps), this means there will still be some yellow in their color which you want. LED upgrades will be strictly limited to the doors, footwell lights, license plate, parking lights, dome lights, map lights, and courtesy lights. The glovebox will be using the standard halogen bulb in a long life factor (its currently burnt out).

Engine - I will be replacing the ignition system (cap, rotor, coil, & plug wires) with an MSD setup, and the spark plugs will be NGK Iridium IX's. The fuel system will be professionally treated/cleaned through a treatment service to clean out any carbon and unclog any injectors. After the treatment I will be replacing the fuel filter with a Bosch fuel filter to help keep the fuel clean when coming to the engine. I will be cleaning out the throttle body by hand as well as the IAC and the EGR filter disks in the UFO looking housing (My 95 Camry had these, they get nasty and the part is $2.99 for the filter media). I have already cleaned out the airbox and aux intake tubes, they were pretty nasty. I will be using a K&N drop in air filter, and I will be replacing the stock mufflers with performance ones that have alternating baffles to keep interior resonance to an absolute minimum while providing a more "factory sport" sound (these will be PROFESSIONALLY installed and MIG welded). While these mods may not actually translate into more horsepower due to the ECU programming being factory, what it will do is make it easier for the engine to produce a powerful spark easier, intake air easier, and atomize fuel easier making the engine do less work and should help with fuel economy and produce less carbon in the engine.

Routine Maintenance - I have already spent $160 on having my car professionally detailed (it took the team 5 hours to complete the detail), and it looks fantastic almost showroom quality. The transmission fluid and power steering fluid were just flushed and refilled with BG synthetic fluids. The oil will be AMSOIL Signature Full Synthetic 5W-30, paired with a Bosch Premium filter (it tested better than the AMSOIL filter), my average cost of a oil change every 10K miles will be $65, but AMSOIL is a fantastic synthetic oil.

This is pretty much where I am sitting right now, thoughts?

[sha4000]

Sounds promising. Where are the pics of the professional detail?

[Spartan0536]

It's been around a week since the detail, but I have been using detail spray to keep it looking good. I personally cleaned the engine bay by hand.

 

[sha4000]

Looks good, makes me want to go clean up my engine bay and find another battery cover.

[Spartan0536]

Here are the instrument cluster pictures as promised, sorry it took so long. I have the pictures with the car on battery power, idle park, & idle drive in that order...

 

[CELSI0R]

Your cluster actually appears to be fine. I noticed the tachometer needle is slightly below 0, but when the cluster is off, does it drop further below the 0 marker? If it does, it needs to be relocated.

I would still have Tanin take a look, if it won't cost more, since you're sending it to have the odometer fixed.

[Spartan0536]

12 hours ago, CELSI0R said:

Your cluster actually appears to be fine. I noticed the tachometer needle is slightly below 0, but when the cluster is off, does it drop further below the 0 marker? If it does, it needs to be relocated.

I would still have Tanin take a look, if it won't cost more, since you're sending it to have the odometer fixed.

Yeah when its off it sits far below the 0...

Also I just finished part of my LED lighting upgrade in my LS400, I have custom type 74 LED's and custom type BA9s LED's coming in through the mail.

I am also considering an LED headlight upgrade, but I am not sure if this is something I want to do, here are the kits I am looking at....

Kit 1

Kit 2

[Spartan0536]

Update:

 

After doing some intensive research for about 4 hours last night I came across some good forum posts and some very informative YouTube videos, I believe I may have found my Headlight LED set, I would like some feedback if possible on this endeavour.

*Note: According to all the documentation I could find on these LED headlights they have a CAN-BUS included in the driver.

GTR Lighting Gen 3 (9004/HB1)

[fsuguy]

If I am following all of this correctly, all your electrical troubles began after the alternator was replaced?  If that is correct, I would suspect the alternator. Have it thoroughly checked out first.  I think the original LS400 alternator is rated at 100amps - remember that the LS has a lot of electrical components all greedy for power.

Good luck

[Spartan0536]

Update....

I am scrapping that mechanic, I swear that guy is ripping my father off...

I sent my ECU out to LSCowboy for repair, he did a fantastic job, took about 25 miles to break her back in after the repair, with some idle issues until after 25 miles or so.

I have been driving it since I had the ECU replaced 2 months ago with no issues other than the splash guard falling halfway and destroying itself so I need a new underbody splash guard now.

My mechanic replaced that alternator 3, yes 3 ****ing times in 4 months! Each time charging $150 for the install and another $150 for the removal, for a total of $300 per trip! $900 in work in 4 months just for the alternator which turned out NOT to be the issue.


Also he tried telling me that my car does not like AGM batteries because of how they are designed.... even LSCowboy called BS on that claim.

I have replaced most of my interior lights with LED's from Philips (no chinese knockoffs here) and have had no issues over the last 6 months regarding them.

Replaced my stereo system with a Kenwood Excelon DDX594, 2x Pioneer TSD-1330C's, 2x Pioneer TSD-1302R's, Pioneer 8 inch B-flats 250W RMS subwoofer and all powered by an Alpine MRV-V500 4way Digital Class D amplifier routed to 5V preouts, all wiring was done by T-Spec using V-12 braided cables and all were professionally installed. The only gripe I have is that it is that the audio is too crisp, needs a little more bass outside of the subwoofer but the clarity rivals that of $300,000 Rolls Royce's. 

I have 4 new factory fresh tires coming from Michelin (Premier A/S) which will be replacing the 8 - 10 year old tires on the car right now which are a 1/2 mix of Michelin Premier A/S and BFGoodrich tires (I checked the manufacture dates on the sidewalls). I am quite sure the new tires will provide a much smoother and quieter ride than these really old ones.

I have permanently modified my fog lights by breaking the yellow glass inside the bulb housing and have replaced the bulb with a H3C 55w Hella Optilux H71071322 bulb set. This has a kelvin color of 4300K which is near perfectly matched with my 4500K PIAA headlights which cost me $70 for the pair.

As for those PIAA headlights, they are good no issues with the quality, however I feel that Silverstar ZXE's would give a "cooler" temperature range and about the same amount of light. So $40 v $70.... if I had to do it all over again.... I would probably go with Silverstar ZXE's or Philips Crystal Vision Ultra's.

My next upgrade I am considering and would LOVE feedback on is switching my headlights to LED's from GTR Lighting, using their Gen 3 Ultra Series, they have me intrigued.

All of my rear lighting is done by Philips, with the brake, backup and running lights being Crystal Vision Ultra bulbs and the licence plate bulbs being Philips LED's.

Also I picked up a few bottles of leather cleaner and conditioner from my local Lexus dealership, it's called Leather Only, and it's pretty darn good stuff, and Lexus recommends it for their leather, it's not badly priced either.

Soon I will have to replace all of the weather stripping and seals, that job might be $800+, and then I am also taking my car to my friends collision center where they are going to buff out and blend the damaged area's that came with my car at purchase (minor paint scuffs) and fix that dent in my floor board from improper jacking (again was there at time of purchase).