1990LS400

Take the car to a real mechanic who can tell if it is a fuel starvation problem or something else. Don't even think of removing the fuel tank at this point.

You might first swap the bulbs to verify they are OK.

Vixster, any chance you can find someone with a 98-00 LS400 with Nakamichi to test your amp in? It is easy to remove the amp in a 98-00 LS without removing the front passenger seat. Run the seat all the way forward, tilt up the back of the seat cushion and remove the plastic cover and a few screws. The front of the amp is held in place by one or two metal taps that slip into a slot - you would likely need somebody to guide these tabs in the slot when reinstalling the amp like I did. Remove the plastic amp cover in the "donor car" and unplug the connectors from its amp - it is not necessary to remove the amp. Lay your amp on the rear floor of the donor car and plug the donor car's amp cables into your amp. If your amp works in the donor car, you know that the problem is likely in your head unit.

It's hard to say what the cause of your problem is. When the right channel of my identical 2000 LS400 Nakamichi started cutting out and eventually quit working some years ago, everyone said that the amp was the problem. I tested my amp in a friend's 99 LS400 and found that my amp was OK. I sent the Nak head unit to http://www.carstereohelp.com/lexus.htm in Florida and they fixed the problem by resoldering the balance control. Last I heard, the Florida shop won't touch Nakamichi's due to parts not being available. You might still contact the Florida company .... or http://factoryradioservice.com/index.php in California if you want to try a repair or buy a used replacement. It would be best if you could first figure out which component is the problem. There is always ebay - always lots of Nak's for sale there. My friend who used to have the 99 LS400 bought a complete 98-00 LS400 Nakamichi system from a ClubLexus forum member for a few hundred dollars except we later found out the problem with his original Nak was caused by the phone transciever in the trunk shorting out and muting all the speakers.

Just one more thing. I've never heard of cylinder compression failing and falling uniformly. When an engine is worn out or damaged, the cylinder compression is (I hate to use the word "always") all over the map. You might have multiple cylinders with the correct compression and one or more with far less and even no measurable compression. It would be extraordinary and maybe unheard of for all eight of your engine cylinders to uniformly test between 80 and 90 psi.

The cylinders not dry? A proper compression test is done by testing each cylinder mutliple times and averaging the readings. Then for each cylinder, a small amount of fairly heavy oil (30W or 40W) is squirted through the spark plug hole before testing compression again. The compression in a worn cylinder should jump significantly after the heavy oil is squirted in. I guess you could buy a compression gauge and test it yourself. They are pretty inexpensive and it's certainly not brain surgery. You would also need a remote starter button if you do not have someone to assist.

Audio system diagrams are available on the EBSCO ARRC website - available at no cost through many public libraries. I've never seen general wiring diagrams for Lexus cars on the Internet or on Lexus forums where I have been hanging around for about 10 years. $15 for a 2-day subscription to TIS is cheap compared to the $250+ I paid for each set of manuals for my Lexus cars.

Not really unless you are a car audio repair shop. It takes no more than 15 minutes to replace the head unit in a 98-00 LS400. Be very careful taking out the center vents - they break and/or fall apart very easily. There are small release tabs on either side of the vents that you can reach by sticking a small screw driver through the vent louvers. The wood console trim/ashtray unit usually can be pried up without much effort. My favorite tool for this is a stiff blade putty knife with the blade wrapped with electrical tape. The radio head unit is held in place by four 10 mm bolts - two top, two bottom. Be careful not to drop anything or you will be searching the top of the transmission tunnel for lost parts. Spread a towel on the console so that you don't scratch it when you pull out the head unit.

I sold my 1990 LS400 in 2003 so I cannot take a photo. The rear lights of 1994-1994 LS400's sold in Europe were wired differently than those on LS400's sold in the U.S. In Europe there were two different versions -- the "German" version and a version for the rest of Europe. You should be able to tap into a wire leading to the stop light in either the left or right rear fender to power the center stop light you add. I think all you will need is an electrical test lamp to find the brake light wire. This is usually easy. I have added center or twin rear window stop lights to three cars: twin Hella rear window stoplights to a 1983 Honda Accord, a Porsche 944 center stop light in a 1984 Honda CRX Si and a 1986 Mercedes 300E center stop light in a 1979 Mercedes 240D. It was never very difficult to do.

The UCF10 sold in North America had a center stop light in the back window. Attached is a photo of the 1990 UCF10 that I used to own. The shape of the subwoofer speaker unit in European generation one LS400's seems quite different than those in LS400's sold in North America.

Michelin Primacy MXV4. We have them on both our LS and Camry and they seem to be extremely popular with Lexus owners. Why would you want to use a difference size? "Road howl" happens as tires wear. How many miles on them? Are they the original tires? There is a remarkable variation in the amount of noise various brands and models of tires produce. The Michelins are known to be unusually quite. Consult the customer feedback on the Tire Rack website for opinions on the noise that various tire models produce. Don't get me started on Volvos - I owned three in the 1970's: 1971 145, 1972 P1800E, 1978 242DL SRO.

Does your 1994 LS400 have a center stop light? The shape of the center stop light in the UCF10 is very different than in the UCF20. In the UCF10, the center stop light is integrated with the subwoofer speaker grill. In the UCF20, the center stop light is completely separate and not attached to the subwoofer speaker grill.

I've recently seen LS/GS400 motors on ebay for about $1,000 but not with the transmission. If this is a "hobby car", have you considered doing your own rebuild?

The possible causes are many. Has the vehicle been repainted? Has it been garaged? Has it been waxed occastionally (i.e. minimum of twice a year) since new? Has it been regularly parked in an industrial area where there are chemical plants? Do you live in a high polution area? The paint on a friend's car started pealing off after parking in an industrial area for several years - in the "west bottoms" of Kansas City. I hate to think of what that polution did to her lungs - but heck, she's about to turn 62.

The only conversion kit source I am aware of is http://www.strutmasters.com/Lexus-LS-400-Air-Suspension-Front-Conversion-Kit-p/-ls400-f.htm

How many people in the U.S. do you think have done something like this? Two, three? Why don't you buy components from an LS designed for the U.S. The Japanese market engine ECU might get you the Japanese market speed limiter -- but "only" 112 mph should be way more than fast enough. The speed limiter was 150 mph on North American LS400's and the equivalent of 156 mph on those sold in Europe.

The 1994 LS400 owners manual on the U.S. Lexus website has diagrams of the fuse boxes and description of what each fuse is for: http://drivers.lexus...49U/pdf/6_4.pdf Yours may not be exactly the same if you have an LS that was not made for the U.S. or Canada.

Just checking: You have the ignition switch in the ON position; the transmission is in Park; you press and hold the SET button and then press L1 or LS while continuously pressing the SET button. I checked the repair manuals for my 2000 LS400 and see that there is a fairly lengthy diagnostic procedure for this issue which involves the use of the Lexus handheld scan tool. We could speculate about the cause of the problem but the lowest cost solution is probably to have someone familiar with the diagnostic procedure figure out the problem.

Let's not celebrate until after the valve cover gaskets and rear seal are replaced. The compression figures are low but that could be related to the testing method; it's more important that they are consistent. Let us know how it turns out.

I don't think you will find a more detailed diagram than the one I provided. I've got the full set of official Lexus repair manuals for my 2000 LS400 and there are no console disassembly instructions in them. From my experience disassembling the consoles of Toyota and Lexus vehicles are generally the same - wood and plastic panels held in place by friction fittings and sometimes a screw bolt or two hidden under a pry-off removable vent cover or similar. I'm guessing that your console box can be pried out like the one in my LS. Sets of hard plastic interior trim removal tools can be purchased at auto parts stores. One of my favorite tools for interior trim is a stiff metal blade putty knife with the blade wrapped with a little electrical tape to prevent damage. The main thing to remember is to be gentle but firm. Work your way around a trim piece and pry a little at a time. If something doesn't want to let go, stop and look for hidden fasteners. Sometimes interior panels and trim can be pretty hard to remove. The first time I removed the console wood in my current LS, it was a real bear -- I've removed it several times since and it has been easier but maybe it is now because I know exactly where are six hidden friction fasteners are located.

Wow! Five years ago and they still did the work for free long after the car's basic warranty had expired. Very unusual.

Was the TPS defective per the diagnosis procedure or was it replaced assuming it was defective?

Ask your Lexus dealer. I would expect that oil consumption of one quart per 3,000 miies would be considered well within the "normal" range. Maybe you should meet the author if this thread: http://us.lexusownersclub.com/forums/index.php?showtopic=72849&hl=&fromsearch=1

Is that what an upholstery shop wants? The leather for redoing your entire interior is just over twice that price from https://www.leatherseats.com It's a 14 year old car. How much are you willing to spend?

You need to be checking the oil level frequently and not waiting for the low oil light to come on. The low oil light on most vehicles comes on when there is very little oil is left in the sump - as little as one quart. Exactly how much oil is being used between 5,000 mile oil changes? Quarts? Gallons? Barrels? I think you need to have a compression test done. I don't know what the design of the compression and oil control rings on your GS is but usually a good compression test is a good sign that the oil control rings are likely OK. My main advise is to take your time unless this is some kind of emergency. Get other opinions.