No Check Engine Light

[Be_Kind]

I have a 1993 ls400 that im having issues with the fuel and sensors anyway , I noticed my check engine light going off and on and now that I want to read the codes ... there is no check engine light at all ! Im taking it to Oreillys and have it put on the code reader since I cant do it myself but just wondering what would cause it to go off ?

...and of course the instrument cluster is out , that's another issue for another day !

Thanks for being such a helpful forum ...I always come here for info ! Be_Kind

[landar]

I would not bother with O'reillys, just do it yourself with this procedure -> http://www.lexls.com/tutorials/intro/codereading.html

[Be_Kind]

I have always used this method to get the codes and I would do it myself now but there is no check engine light ! It has stopped working , stopped lighting up , I don't know why or how to fix it ! Oriellys couldn't read the codes for me because of the same reason...no check engine light !

[landar]

Engine codes can clear out on their own and then the CEL would be off so maybe that is what you mean. Lets cut to the chase...what is your main issue with the car?

[Yamae]

Your type of problem is often caused by the failed ECU which has too much ripples at the processor's DC line. Check electrolytic capacitors inside of it.

[Be_Kind]

My trouble started last summer which resulted in a new fuel pump , filter, and all that that applies but some of the issues never got fixed ! It is a fuel problem and I need to replace a couple of sensors but I wanted to be sure which ones so I need to get the codes again. what its doing is....The first start of the day takes a little time but ones the fuel like builds up , it will stay running until it starts dying at random times,sometimes it starts right back up and sometimes it takes a while, and its mostly at stop lights when it dies so the ppl behind me get a bit up tight, or the rpms rev up and down very fast (up down up down up down) or the rpms shoot way high and stay that way till I turn the car off ! I need to get the car winter ready , I have 2 grandsons one is a 9 month old and a 5 yr. old which I take to school so I need it to be safer than it is at this time and there are to many problems for them to fix its self altho that would be a dream come true !lol Is the check engine light and the cig.lighter tied in somewhere together? Seems like I heard someone say that ! It doesn't even flicker when I start the car !

[Be_Kind]

Have an appt.to have car put on big scanner this after noon ! Crossing my fingers that it works !

[landar]

The Check Engine Light (CEL) and cig. lighter really have no common link other than the battery as does every thing else.

What is the history on this car? How many miles, how long have you owned it?

Have you or a previous owner, ever had the trunk wiring harness looked at? Weird electrical issues occur when the wires are intermittent.

[Be_Kind]

Heres what the scanner came up with that I need....all 02 sensors, throttle pos.sen., coolant temp sen. and tune up ! Can you list for me all the 02 sensors ? That would be great , im looking up parts now at Rockauto.com and auto parts warehouse.com or is there a better cheaper place I should look ?

I have owned the car about 8 yrs, it has about 240 thousand miles and all I know is the owner b4 me kept up everything at the dealership!

[landar]

Sounds like they are taking the 'shotgun' approach. Here is some reading for you -> http://www.lexls.com/tutorials/EFI/

[SRK]

Find a technician that knows what they are doing and don't buy any of those parts. The O2's will not cause surging like you are experiencing, and all four will not fail at the same time. All four could be out of range, or pegged at one end of the scale or the other, but that would be in RESPONSE to something else causing a poor fuel ratio.

TPS and Coolant sensor will pop codes specific to themselves.

Surging can only be caused by air flow - the idle air control valve is not at fault, but probably responding to something else, which causes the ECM to command and IAC valve change.

Whatever it is it will be a simple thing. Find it, and fix that one thing. To do that will require a tech who can investigate further than just reading a code number and running a finger down the list.

Your choice is to believe the folks on this board, or the less-than-capable mechanics you've found who want your money.

[Be_Kind]

I ALMOST fixed it ! I took my dash apart and replaced the capacitors and after a yr of not having dash lights or knowing how much gas I have ....I fixed it except for the odometer didn't light up. Now im trying to see what that fix will take so I can go get new tires ...I need that working for the warranty on the tires !

I ordered a throttle position sensor from rockauto.com ...gonna start there on the fuel fix !

[SRK]

So you've determined it's the TPS then?

[Be_Kind]

That's one sensor that we are sure needs replaced

[Be_Kind]

I need to find out about the odometer and how it wires in to the instrument cluster

[LSPaul]

One other thing to check is the bulb for the "check engine" light, itself. I've had to replace that particular bulb on my LS. IIRC, it's mounted in the bezel, not the instrument cluster.

Paul

[Be_Kind]

Here is an update...

About the odometer not giving a read out , It was there the whole time , but reading 252miles , apparently when I took the dash out and put it back in , it reset the odometer , I know that sounds crazy but the only other answer is that the miles rolled over and that cant be right ! I looked it up and it has happened to others ! By it only reading 252 miles I over looked it , I was looking for 250,000 miles ! Every mile I drive ... its adding on as it should !

And as far as the fuel issue , Please understand , I am single and rely only on myself for any money coming into my hands , if I don't work I have no money , work has been hard to find and as you know lexus parts and in shop time cost a pretty penny , not just any one can work on a lexus and I have 2 people I trust and they aren't always handy so Im learning to do some of my own troubleshooting , and trust me , Im just a learner doing what I can to fix my car , the colder it gets the harder it is to start , and with that being said ....I do trust those here who have sent input and tried to help me and Im pretty sure the Idle air control valve isn't clicking !

[Yamae]

 

I ALMOST fixed it ! I took my dash apart and replaced the capacitors and after a yr of not having dash lights or knowing how much gas I have ....I fixed it except for the odometer didn't light up. Now im trying to see what that fix will take so I can go get new tires ...I need that working for the warranty on the tires !

I ordered a throttle position sensor from rockauto.com ...gonna start there on the fuel fix !

Why don't you replace ECU capacitors as you did for the dash aparting all by yourself. Electrolytic capacitors do not last long especially Nichicon's electrolytic capacitors that containing quaternaty ammonium salt" in the ECU fail easily. For a person like you, replacing ECU capacitors is not a diffucult job. I'm sure some of your problems will be disappering doing so. You can find the detail at below.

http://www.clublexus.com/forums/ls400/656360-all-my-crazy-lexus-issues-solved-ecu-leaking-capacitor.html

[Be_Kind]

Thank you so much for your advise ... I ordered the capacitors to be replaced before I saw this last post , they are in(from Digi-key) and I am getting ready to get ready.. haha the capacitors are going in today ! I will keep you posted !!!!

[Be_Kind]

I need your help again.... Since I was last here I have replaced the iacv (took mine out it was broke inside) Took out the Icu and replaced the capacitors with new ones from digi-key , replaced the throttle position sensor with a new one , and its been running good , not perfect but way better than it was , No trouble starting it and it hadnt been dying untill one day last week it died and wouldnt start again, so I replaced the fuel pump AGAIN today but it still wont run , it starts for just a second then dies out ! Its been setting in walmarts parking lot since last week so I need to get it somewhere to work on it , my friend has a car dolly but im unsure about messing something up !

Any suggestions on what to look at now as far as fixing this dang car ? Thanks again guys , be_kind

[landar]

I am not sure why you replaced the fuel pump the second time. If you do not want to just be throwing money at this car, you are going to have to do some fairly simple troubleshooting. That involves determining whether the issue is lack of fuel or lack of spark. Once you have determined that aspect, you can start further testing the components responsible. The main problem that seems to frustrate owners is this lack of logical, progressive troubleshooting.

So, I would suggest that you try checking for spark when it won't run and if it is there, check for fuel. How you do that requires some mechanical skill but not much. You will have to pull a plug wire or the main distributor wires to check for spark and you could spray(carefully) some starting fluid in the throttle body to check for fuel delivery.