Yamae

I know this is an old thread but I dare write this for those who suffer and try to fix it inexpensively as a DIY job. Recently a friend of mine mentioned about Mark Levinson's amplifier and I posted this to the Clublexus. According to him, the popping/cracking/static noise is mostly caused by the oscillation of the voltage booster at the power supply block. All you need to do is just to replace worn electrolytic capacitors used there.

Catalytic converters glowing red simply mean that they are working properly because the unburnt fuel is burnt there. The problem is that the feed back system is not working right. Since you already have replaced the mass air flow sensor and and TPS, remainings are ignition related parts, injectors and the ECU. I would check the ECU first since it uses infamous QAS capacitors inside and they fail after aged. There were many people like you who were having the same problem with you and they now are happy with new capacitors.

No. you don't need to do so at all as long as the memory is not changed. But you must teach the ECU your driving habits. All you have to do is just to drive both in the city and the highway.

Yes. The link below may help you to know more about the NSS. https://www.clublexus.com/forums/ls-1st-and-2nd-gen-1990-2000/683483-does-this-sound-like-a-bad-starter.html#post7837082 One correction at my previous post : The line to brake lights (12V) ---> The line to back up lights (12V)

Sounds like the copper dust in the NSS is causing your problem. The line to brake lights (12V) and the starter relay line in it must be leaking each other. Remove it and see inside of it and you'd be amazed at the mess.

When was the last time to change engine mounts?

When I had begun to explain how those QAS capacitors used in the ECU were risky several years ago, almost no one has paid any attention nor understood me. May be because my English was limited. But LScowboyLS was the first guy who understood me well and also he had succeeded to fix his LS400's ECU. Then he decided to started the thread," All my crazy Lexus issues SOLVED!! (ECU-leaking capacitor)". As a Japanese engineer myself and a guy who knows some behind scenes of the car, I recommend you to replace those capacitors for a preventive measure. If you are not good at the soldering work, ask him for a help. He does have good knowledges, skills and the experience. My intention is to keep our precious LS400/Celsior on the road longer. One of the most serious problems is the ECU capacitors issue and I suggest you to replace those before the board is damaged by the leaked liquid which is very strong alkali.

Things are a bit more complicated. In order to send accurate speed signal to the cluster, following process is done in the ABS/TRC/VSC computer monitoring and processing 4 speed signals from FL, FR, RL and RR hubs. 1, When all 4 sensors are getting signals properly, averaged RL and RR speed signal is sent. 2, When either one of rear speed sensors is not getting the signal properly, the one getting the signal is sent. 3, When both rear speed sensors are not getting the signal properly, averaged FL and FR speed signal is sent.

You can test it only partially just measuring the resistance. The drive circuit is organized by semiconductors and the resistance varies depending on the measuring equipments since the applied voltage is not the same. Some shows 300 ohms and some other 500 ohms. Lexus_DK's method is a good choice. Another simple and useful method is to use an air gap of a half inch instead of a spark plug. A good arcing energy can travel more than a half inch in ambient atmosphere.

In case of LED brake lights, there is a way to modify the sensor circuit. You don't need to use any resistor. I have written it at the Clublexus Forum. http://www.clublexus.com/forums/ls-1st-and-2nd-gen-1990-2000/747365-how-to-modify-the-tail-lights-failure-sensor-for-ucf20-21-a.html

The sound level of the click is quite low to me and it makes me to think that it may be caused by the neutral safety switch. Have you tried to start at the AT position "N"?

How long does it run? If it runs only 3 or 5 seconds, I can give you additional ideas.

>3. Are there any other troubleshooting procedures that I could employ ? It seems to me that your symptom "150 miles run and then the check engine light comes on" is caused by the abnormalityof the emission system of your car. You'd better to check the efficiency of the CAT, vacuum leaks and others. In my experience, most of those were caused by the air leakage at the exhaust line. Some old cars had failed CATs.

The leaking power steering oil damages the slip rings and the brushes most. These have a rubber cap and the oil from above does not go into them directly and quickly but it does go in little by little and ruins them in a month or so because the airflow is there from backside to front side. At the early stage, the resistance between the slip rings and the brushes increases and the out put voltage becomes a bit lower. You can save the alternator cleaning the inside at this stage. But if you let it go, the voltage is getting lower and lower and finally the alternator is dead and stops the function. I have seen some of those dead alternators and found that the slip rings were deteriorated.

I have fixed this problem for several cars so far and every car is running as is new.Believe it or not, it is caused by the clogged throttle body and the clogged air mix path for injectors. Cleaning them well will fix the problem. LS400/Celsior after 98 does not have a IACV. The main throttle valve controls the air flow from the idle to the max power. When the throttle body is clogged too much, the ECU is confused and your type of symptoms occur as results. The link below may help you to act some more with photos. http://www.clublexus.com/forums/ls400/612441-still-low-idle-in-drive-at-stop-what-you-think.html#post8164859