1991 Lexus LS 400 - Page 2 - Answered Questions & Fixed issues

check engine light is obviously telling you that you need to take to a lexus approved mechanic who will have the diagnostic equipment for your age of vehicle which is known as OBDI , there are many reasons for these symptoms mostly electronic so would need to actually be with vehicle to help better

Have you checked fuses? Test them, don't rely on being able to see they're blown as they'll sometimes have a fine crack that's hard to see. If you need further help, I’m available over the phone at https://www.6ya.com/expert/oscar_403cc49e0f00cda7

Could be a bad brake light switch or the solenoid itself or wiring. See if brake lights work. If they don't then check brake light fuse, if thats ok then check at the brake switch for power or jump the two wire plug lights should light and shifter work unless solenoid bad. Good luck

Most all pressure regulators are located on the fuel rail under the hood. It should have a vacuum line attached to it

Try this site: www.lexls.com

Most likely if its anything like the old lincolns the airbag/shocks are blown. If this is the original set on this vehicle very good possibility. Best fix is a replacement set or if the coil over option is available much sturdier.

Dirty injectors...try adding 2 bottles of Lucas Oil Gas Treatment...drive a day or so and feel the difference...also old dirty gas...has your Lexus sat for awhile?

There are 2 fuse boxes on the Lexus. The first is the main power distribution box and is located right beside the battery under the hood. The second panel is located behind the plastic kick panel under the dash on the driver's side where your feet go. The panel is vertical and covers the area from the dash to the carpet on the floor, just forward of the door. I can't remember if it's a pull off or if there is plastic twist nuts holding it, so check carefully before pulling on it.

Disconnect the seat heater and use a meter to check if there's any continuity on the heater or if it's an open circuit. If open, then heater is bad.

display dtc codes

MAP sensors are not cleanable, MAF sensors are.

Nothing to clean. It either works or not. Make sure the vacuum hose to it isn't cracked or loose fitting.

Or maybe too much fuel-backfiring in the exhaust is the burning of the unburnt fuel in the exhaust. Check the fuel pressure. You can rent fuel pressure gauges at autozone, I believe. If too low, possibly a bad filter or bad pump. If too high, test the fuel pressure regulator. a failed regulator can let extra gas into the engine through the vacuum line on it. Take off the vacuum line to the regulator, and watch the regulator for a minute with the engine running. If gas starts oozing out of the vacuum port at the pressure regulator, the regulator has failed and must be replaced. If pressure is correct, at least you have eliminated that as a problem. Check the air filter, check spark plugs and plug gaps, more or less back to basic tune up.

Check to make sure that none of the wire harnesses are touching the exhaust manifold and that the fuses and bulbs are tight in their fixtures.

You may be able to clear debris out by using a long thin rod and pushing it into the openings on the front of the sunroof drain channels the pouring some water in to make sure it drains properly sometimes the drain pipes become disconnected inside the headliner but try clearing the obstruction first and see what happens.

This might be air intake temp sensor or vapor lock.

i have done a many of these on your type of car its a lil more difficult. you will have to locate it and get to it the best you can take a sharp object,preferably a small chizzle and pop a hole in it once you have a hole you can slowly start to pry down ward to try and pop it out once you have it out they offer a universal freeze plug at the autozone's i recommend the universal it'll be alot easier to put in....good luck

Fuel Pump it's inside of the fuel tank.

It is simple and complicated at the same time; do not do it by yourself since you may brake the fuel line and it will need to be replaced entirely. My advice is, go to the dealer, it pays to have peace in mind

I don't know about back seat access, but you may have a feasible idea about the 12volts -maybe. Does your vehicle have a button on the dash to pop the trunk?? If so, that button works with the ignition switch in the 'on' position. Obviously you can't use the button since you can't turn the ignition to on. However, if you can get to the contacts of that button, you may be able to energize the trunk opener. Hopefully there are only two wires on that button switch, which will simplify matters. If you take a wire from the Positive battery terminal to the button switch, you may be able to energize the opener. If it's a two terminal switch, one side or terminal is power (12v) in, and the other terminal is 12v out. If you put 12v to one terminal and nothing happens, push the button. Can you pop the hood to get to the battery???? If not any 12v battery can work, lawn mower battery, etc. : Negative terminal of battery to car frame, positive to switch. This would be a low current draw, so the wire can be anything like speaker wire. Since the wire is live, just be careful not to have it touch any other bare wire connections or part of the frame, etc.If this works, it will probably set off the alarm, since the ignition switch is off. I really don't know if this will work, but if I was in this dilemma, I would try it. After all said and done, someone might be able to tell you how to access the trunk by way of the back seat. GOOD LUCK!!!!!!!!!!