jd04401

Hello, I just recently purchased a 1992 LS 400 with 127,000 miles, the car has a check engine light on and the "trac off" light is on. I checked for code and codes 25, and 52 were present. I believe this is a knock sensor and a lean fuel mixture, the "trac off" light is also on. I dont have a Lexus mechanic close by and will probably have to use a mechanic that is not familiar with this car. I am hoping for some direction on were to start if these codes may be related to one another. Any suggestions or info would be greatly appreciated.

deanshark

First, welcome to CL, hope we can help.
The manual shows the trouble area as;
For the code 25: Air-fuel ratio lean malfunction;
Open or short in main heated oxygen sensor circuit
Main heated oxygen sensor
Ignition system
Engine coolant temp. sensor

Code 52: Knock sensor circuit;
Open or short in No. 1 knock sensor circuit
No. 1 knock sensor (looseness)
ECM

I don't see how they are related but someone else might chime in who knows more about it and say different. Is this how you checked for codes; http://www.lexls.com/tutorials/intro/codereading.html
Did you check for "trac" codes? For that you place the jumper wire in Tc and E1. If there is codes for the trac system remember, you count the blinks on the "trac" light, not the "trac off" light.
This may be a dumb question but, for the trac off, did you try using the button on the shifter to turn off the trac control? For the code 25 you might want to try changing the ECT first, it's the cheapest and easiest. Check the wires for the rest for loose connections. If you end up having to change the knock sensor, it would be a good idea to rebuild the starter at the same time b/c of the labor to get in there. (they're both under the intake manifold)

jd04401

Thank you for the response, and the welcome. I did not check for "trac" codes, but I will and reply back. Unfortunately right now it looks like my best option for repair would be to bring this car to my local toyota dealer, quite possibly the most expensive as well but I figure I can at least hold them accountable on repairs, or so I hope, before I do though I am curious to hear some more feedback so if at least I end up spending alot on repairs I get the most value for my dollar. I did try pressing the "trac" button to see if the "trac off" light would go out and it did not. I will check that code and post it on here as soon as I have it. Thanks again for any and all help.

jd04401

Ok I just checked for "trac" codes and it gave me a code 51 , I read this is a problem for engine control system, hopefully this may shed some light and maybe these issues are related.

deanshark

Code 51 for trac: Engine malfunction detection circuit;
Short in TR5 circuit (This is the connection between the ECM and the TRAC ECU)
ECM
TRAC ECU
Diagnostic Chart says;

Check the diagnostic trouble code for the engine (which you did)
Repair engine control system according to the code output.

Then it says; If the malfunction indicator light remains on;
Check for short in all the harness and ECU connected to malfunction indicator light.

It sounds like if you take care of the engine codes, the trac code will go away also, I'm not 100% sure though. About the dealers; Toyota will be cheaper then a Lexus dealer but still expensive. You might be able to find a good independant shop that deals with these cars for alot cheaper, ya just gotta check around.

vicious

also have the same problem.. i recently was gonna attempt to replace the stereo and stopped midway through cuz the air vents werent comming out smoothly, so i re-attached the harnesses and put it back. shortly after the "trac-off" light at the bottom, "TRAC" light and "check engine" light came on.. at one point they turned off, so i figured problem solved itself and until couple days ago they came back on

jd04401

Thanks for the info, I figured I would provide a little more information on my recent investigating. I went out and pulled the EFI fuse and cleared codes, I then took the car out on the interstate and around town for a while to see if codes reset, before I even reached the end of my street, both the CEL and the TRAC OFF light were on, I kept going to check on performance, it idles great but feels sluggish, when getting on the interstate it was quite slow to come up to speed, and felt some intermittent hesitations, possible misfiring. Upon my return I checked codes again, the only engine code present this time is code 52, and still the same TRAC code of 51. So I am thinking when I take it into Toyota to ask them to do, both knock sensors, check wiring, and obvious intake gaskets. Do you think a tuneup is necessary as well? I have never driven one of these cars prior to now, but assumed there would be a little more power. Also maybe I should get the starter done, it seems to be fine, however if the intake has to be torn down, I do not know that they would rebuild it though, as they would probably replace it, that may get expensive. These are my thoughts, I welcome yours. Thanks in advance...

deanshark

Well, you did the right thing with checking, clearing, and rechecking the codes. I don't think you would have to change both knock sensors, (they're expensive) just the one that's giving the code. (If it's actually bad) As for the starter, there's a kit that's sold by the dealer which includes the contacts and plunger. That's what I meant by rebuilding it. That's what most members here do when they have starter problems. It's common. So they can do that while the intake is off, shouldn't take too much more time if they're already in there. Use the search feature (it's a big help) at the top of the page and check for "starter replacement" and you'll get all kinds of info on it. As for a tune up; I usually do it as soon as I buy a car but I don't know your financial position so that would be up to you if you think it needs it. Do you know when it was done last? The ECT should be changed no matter what, it's about $25 at Autozone, changing it does amazing things. Search on that too.

jd04401

Thanks again for all the info, I will be sure to post all of my results.

jd04401

Well here is an update, I had my apoointment at the Toyota dealership, and well things took a strange turn, they said the CEL is a result of the Throttle Position sensor..... ???? I asked multiple times if he was sure, they said that would fix it so I scheduled it. They also picked apart the rest of the vehicle, fuel lines, steering rack, power steering pump, steering lines, transmission pan seal, oil pan seal, rear cv boots leaking, and gave me a ridiculous quote. I scheduled the throttle position sensor repair estimated at $260.00, as I was promised it would take care of the CEL, is it possible a faulty tps could cause these codes??? As for the other items how many hours labor for the rack and pump, the cv shafts? I think I will do the repairs I can and find a local shop to do the rest. I saw the rack, and pump and other items on EBAY pretty inexpensive. Anyways, theres an update, curious what is thought of the TPS diagnosis. Thanks in advance.

deanshark

Wow they found alot wrong. But then again, being a dealer, they're gonna pick out everything they see. That is alot seeing how it only has 127K on it, but you are from Maine. We use alot of sand and salt here in New England. About the TPS clearing that code; ya know, I think it just might. When I was searching old threads the other day about your codes, (nothing better to do) I think I saw someone who had changed the TPS and it went away. I didn't mention it b/c it just didn't sound right to me. Check out these tutorials for any kind of repairs you can do yourself. http://www.lexls.com/tutorials/ You might want to get a second opinion on some of the other stuff like the steering rack, is it leaking or maybe just the filter needs cleaning in the solinoid. If the power steering pump is leaking, that's something you would want to get done soon b/c they leak onto the alternator and kills that.

vicious

so wait, did u find a solution to the TRAC OFF. TRAC, ENGINE light being on?

jd04401

Thanks for the reply and thats reassuring that you have heard that, it didnt sound right to me either, im still unsure but hopeful. I am definately going to get a second opinion on the rack a friend has a lift I can use, is the filter in the rack hard to do? The fuel lines I can do myself, The oil pan and tranny pan gasket I will inspect and see how bad they are, and yes I have heard many storys about the issues a leaking power steering pump can cause, ie the alternator. How is the power steering pump to change?

Oh and vicious, as of right now the dealer stated my "cel" which was a code 52, knock sensor code, and my "trac" code 51 engine malfuntion code, are related to my "Throttle position sensor" they are charging me about $260.00 for the repair and are going to replace it with a OEM toyota sensor, im unsure if this will correct it just yet, but it is a cheaper repair then the potential knock sensor's repair.

Anyways I will post the results as soon as I can, it may not be until sunday or monday, taking the family on a weekend trip unfortunately not in the Lexus. lol