chc0318

If you didn't rebuild your ECU recently, might be you should check ECU to see any capacitor leaks, since it is a LS400 common problem. best wishes.

You can find more info about how to replace LS400 starter info on the net, such as

Lexus LS400 instrument gauge failed is a common problem which caused by transistor leak. My 1993 Lexus LS400 (216000 miles) instrument repaired at about 150000 miles. I send it to https://taninautoelectronix.com/product/1990-2000-lexus-ls400-instrument-cluster-repair/ or you can google search "Lexus LS400 instrument gauge re[air service". If you have skill to change transistor. You can search the parts on Ebay and DIY. Replace knock sensor, you can reference the following link https://us.lexusownersclub.com/forums/topic/31948-replace-knock-sensors/ I change knock sensor when I replace my starter. It is not difficult, but it need remove the intake manifold and take time. when you change it, you'd better change your starter at the same time. I changed my starter around 190000 miles.

How many miles? You might need to replace your fuel pump control module relay.

You might can buy it from https://www.amayama.com But it is too expensive ($408.00 + ~ 31.15 shipping).

I turn off my alarm by insert the key.

Any Diagnostic Trouble Code? Does the engine stop when you stop on the traffic light? If yes, you need to check the EGR valve.

It is a discontinued item, I think you need to find used part. Search 1994 Lexus LS400 parts from Ebay, you can find some company sell used parts, then contact them to find one for you. Best Wishes. My 1993 Lexus LS400 with 217,000 miles, still runs very smooth. Best Wishes.

If no error codes, change gas filter might help.

As for my experience, it might caused by your COOLANT THERMOSTAT.

One more. https://community.cartalk.com/t/my-radio-cuts-out-when-i-step-on-the-breaks/45022

Hope you can get some answers soon. In the mean time, I google and get the following info. it might give you some hints. Best Wishes. https://mechanics.stackexchange.com/questions/41321/my-stereo-turns-off-when-i-step-on-my-brakes

I suggest you check the ECU first. You can open the ECU and check the capacitors to see any leaking capacitor ? If yes, you should send out to repair.

Hi, Carl: My 1993 Lexus LS400 EGR valve malfunction, I tried to tested it by the same procedure as IAC valve, but only click sound, not valve movement. I google search and found out you had the same problem before. Have you got the answer? Do you know can I use 25630-50020 (EGR valve for 95-00 LS400) instead of 25620-50020? Thanks.

As I know. Lexus and Toyota share the same parts with the same part number.

As for my experience on my 1993 Lexus LS400, you can try to check the following : 1. MASS AIR FLOW SENSOR 2. crank position sensor 3. camshaft position sensor Best Wishes.

If you haven't read this, might be it can helps. Best Wishes. https://www.clublexus.com/forums/ls-1st-and-2nd-gen-1990-2000/867836-no-reverse-and-neutral-drives-forward.html

Have you tried to search Ebay ?

You can try Step 1 https://www.clublexus.com/how-tos/a/lexus-why-wont-my-lexus-go-into-gear-365738

Yes. you are right. My passenger site switch button was broken. Since I can open it from driver site, so I know the motor is working, the problem must be the switch. Your problem is different. Sorry for the confusion.

Since your motor is running, might be your Power Window Switch Button broken, you just need to remove the button, to check. My fixed it by super glue, you can also buy one on Ebay. such as https://www.ebay.com/itm/Power-Window-Switch-Button-for-Toyota-Lexus-Camry-Corolla-Pickup-Truck/350862715030?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m1438.l2649

If your father didn't repair ECU before, check your ECU first.

I suggested you fix the instrument panel capacitors first.

Check diagnostic trouble codes first.