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Hi.
I have a 93 LS400 with 190k on it. I am suffering the infamous Trac Off - Service engine light symdrome. The SES light comes on followed by the TRAC Off light. A moment or two later they go off. I've read many posts that seem to narrow this down to the TPS or the O2 sensors. I am also experiencing Idle problems. High Idle, Low Idle, sometimes dying at stop lights. So I would tend to blame the TPS, except that an O2 sensor could probably do this also. Ok, here's my main questions.

#1. When I check codes, it comes back with a code 22, which is supposed to be ECT sensor signal.

#2 Every pic I've seen online of the TPS shows only one. I seem to have two of these buggers on my Throttle Body. Which is the TPS? I'm assuming the one closest to the Plenum.

Any help or advice would be appreciated since I dont wanna take it to the dealer after reading the posts here about people having the dealer fix everything else first at big cost before finding the true problem.

Thanks in advance.



Randy

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No Input?

stuart browne

Code 22 is water temp sensor circuit. When trac light and check engine light come on it is alway the two front oxygen sensors. If your trac light came on yes you have two tps sensors, the first one is trac control second is throttle position

stuart browne

The TPS sensor that is throttle is the one near the drivers side, passenger side is trac. If you have never replaced the o2 sensor change them now with 191 on it your convertors will go. Get the universal sensors they are about 60 bucks each Walker makes them.Stay away from dealer they are 150 each . When o2 sensor goes the computer does not know it it needs more gas or less gas, high idle low idle

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Thank you, I will try that. About the code 22. I was going by the code site I found listed on this forum.

http://www.troublecodes.net/Lexus/

Is that site's codes not correct? And, if so, where is one with the correct codes?


Randy

stuart browne

Code 22 is water temp sensor this is out of the master Lexus LS 400 service manual. We get code 22 all the time on older 1990-1994 LS 400, the sensor gets coated from high levels of ph from the anti freeze. You can change the sensor for about 20 bucks any auto parts store can get it for you. To get the codes right all the time you need a code reader or obc1 scan tool, not codes from the radio display.

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Ok. I replaced the front two sensors with the walker sensors. Still does it. Trac OFF light and SES light are still coming on and off. TPS sensor, or what else could it all be?

Randy

stuart browne

Did you clear codes from computer? When ever check engine light comes on and you replace part or parts you have to clear code. To clear code remove EFI fuse it is 20 AMP fuse in fuse block, big black box by battery it is marked under cover. Go buy yourself a proper code reader it is Toyota-Lexus for $30 bucks any parts store can get you one. The way you are getting codes by jumping wires is a hit and miss, when code 22 shows up you can miss code 13-24-41-47. Hope this helps if not get back to me.

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I cleared the computer via disconnecting the battery for a 1/2 hour while I installed the sensors. That is sufficient, isn't it? Also, I will buy a scan tool. I've just seen OBD2 ones advertised for $89. I didn't know OBD1 ones were so cheap.

Randy

stuart browne

Get code reader from www.midwayautosupply.com. Part number is Equis EQU 3173 $29.95 you can also get it from any auto supply place. This is the best one for OBC 1. Before you go any further seeing you left battery cable off do the following. On the check connector that you used to get codes jump TE1 and E1 see how many blinks you get on check engine light leave it hooked up for 10-15 seconds. Do you still have trouble with high and low idle plus stalling?, how long have you had the car?

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OK. I got that scan reader you said, and it still comes back code 22. It died on me twice the other day even. One time it took two minutes until it would restart. Can a bad Temp Sensor cause that much trouble, and where exactly is this baby so I can pull it and ohm it or just replace it?
Also, where online, can I fond a correct listing of the error codes for a 93 LS400, since you say the ones on troublecodes.net are not correct?

Thank you
Randy

stuart browne

The water temp. sensor is located beside the upper water inlet housing, this is next to righ hand ignition coil. To check it pull plug off check when engine has reached full operating temp 180 , resistance should be 0.2-0.4 ohms. The swithch has only two terminals does not matter how you hook it up. Yes the switch can be a big problem the fuel injection system gets it signal when cold to increase fuel volume. When code 22 comes up the ECU runs in open loop this means no extra fuel when cold car dies.Also check switch that goes to sensor turn igniton on do not start car, there should be 1-3 volts present.Have you had this car for a long time or did you just buy it. All the codes on internet are generic codes for OBC 1 to get the code that shows what part is connected to that code number you need Lexus service manuals.

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Thank you.
I checked the ohms on the sensor and it came back at 1. Thats assuming that thelil plug infront of the right hand dist is the right plug. Does anyone know where detailed ( take this off, take that off) instructions for the removal of this sensor may be located online. Do I need to take off the dist cover? I couldnt exactly locate the sensor itself. From the plug I mentioned, one set of wire goes up and to the left to next to the water inlet, but two other harness's from elsewhere seem to dive into that same area. Or, is it located to the lower right of the mentioned plug, under the dist? Lexus told me 2-300$ to change this sensor, and I'd prefer to do it myself if it isn't too hard. Any help would be appreciated.

Thank You
Randy

stuart browne

To replace water temp sensor. Remove intake air connector pipe,remove upper spark plug cover, two engine wire covers, two no.3 timing belt cover and lower high tension cover. Remove righ hand ignition coil then remove water inlet housing. Seeing that you want to do this work yourself invest in the Lexus repair manuals they are about $125.00 for the two books. The above job takes up 3 full pages in my manuals. Note you have to drain rad if not anti freeze gets into timing belt and good by timing belt.

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Yeah. Definatly. Because the timing belt was just put in 10,000 miles ago. I don't wanna mess that baby up.

Thank you again, very much.
Randy