Is200 Check Engine Light, Fault Code P1633. Please Help.

[munkinutz]

Hi guys, new to the forum and the Lexus club...

I am having an issue with my 1999 IS200. I bought the car around 2 weeks ago and everything was running smoothly up until a couple of days ago.

I went to go out in the car and have lost acceleration, the engine management light is on, TCS light is flashing and my scantool is giving me error code P1633: ECM Malfunction (ETCS Circuit). I have tried clearing the code but as soon as I start the car the fault code comes back.

I'm hoping someone can shed some light on what might be going wrong. Has anyone else had this problem and has anyone managed to solve the problem? I have googled for hours and hours but can't seem to find any kind of guide or information on how to solve this issue.

I hope some one is able to help and apologise if this has been discussed in a previous thread.

[Lance]

According the the Lexus repair manual for the code 1633/89 what you have to do is replace the Engine ECU.

[munkinutz]

Hi Lance, thanks for your reply. I have read somewhere that several people have replaced the ECU and the fault still persists. I have been advised to check the Throttle Position Sensor but everything looks OK. I have noticed that the throttle cable is slightly loose, would this have anything to do with it? The cable never used to be slack.

[Lance]

There is information about the throttle body too so it could be worth investigating.

Here is the procedure for testing the throttle body... see the attached PDF

When you say the cable is slack what do you mean? The cable should be tight and be responsive to the throttle pedal.

What is the idle speed of the engine?

Does the throttle body move when you press the accelerator?

Throttle pos.pdf

[munkinutz]

Hi Lance,

Thanks again for the fast reply and thanks for the pdf. I will definitely have a look at the throttle body.

The cable is quite loose and I have had to pull the throttle cable tighter on the engine. The cable looks to have gained around 35-45mm which is making it loose.

I can't remember the exact idle speed (car is at a friends so can't check right now), but I vaguely remember it being around 830 rpm. I will check this for you though.

Yes the throttle body moves when I press the peddle but only when I re-tension the cable. It used to be very responsive until the morning I came to the car and found the fault.

Could I ask where you got the service manual from? The one I have is all jumbled up and all over the place making it difficult to read.

[Lance]

It sounds to me like the fault lies with the accelerator cable or some part of the linkage. I would try and find out where that slack has came from before looking at anything else.

I got the service manual from this man: http://www.ebay.co.uk/itm/Lexus-IS200-300-Workshop-Manual-Technical-CD-/321179705276?pt=UK_CarParts_Vehicles_Manuals_Litterature_ET&hash=item4ac7cd5fbc

Works fine on Windows 8 if anyone is unfortunate enough to have it.

I just copied the disc onto the hard drive so have access to it right away.

[munkinutz]

Ok thanks for the info and the link to the manual. Looks like a worthwhile investment.

I think your right... Will definitely investigate the linkage and cable. I don't suppose by any chance you have any pictures of what the linkage should look like. Would be handy to cross reference to see if anything is missing from my linkage.

Thanks again Lance, your a true gent.

[clifton 94]

hi you could always try a second hand throttle body

[Lance]

This is the best I could do unfortunately. This is a pic of the throttle linkage of a 2001 supercharged IS200 I removed the supercharger from to put on my own car. There will be little differences as in the extra cable but everything else should be the same.

[munkinutz]

Hi Lance, thanks for the picture... It is ideal!

I will be going over to the car tomorrow so will give everything you have suggested a go.

Thanks again for all your help, will report back tomorrow on how it goes.

[munkinutz]

Hi Lance, been to the car today and still scratching my head...

I have checked the throttle linkage and everything is exactly the same as yours. When tugging the cable it moves about half inch before moving the throttle.

The car is idling at 1100 RPM and the throttle position is 16.7%.

I have tried a different throttle body and nothing changes, still have same fault.

I also got hold of another ECU from another IS200 and noticed a difference... Obviously the car wouldn't start as the key was not programmed but I noticed that the throttle operated properly on the replacement ECU.

On the replacement ECU the throttle operated the same as this -

(http://www. youtube.com/watch?v=hl4YsXjEGY4)

http://www.youtube.com/watch?v=hl4YsXjEGY4

However when I use my original ECU the throttle body does not operate the same... If I twist the throttle (or push accelerator pedal), the "inner motorised" pulley wheel doesn't move at all unless I turn it manually.

Would I be right in thinking that at this stage the fault is the ECU itself? I'm stumped now.

Hope all of the above makes sense. Thanks again in advance.

[Lance]

Sounds like your ECU is faulty as it is not making the throttle motor work.

Good work on sorting it out.

[ColinBarber]

Hi Nick

Did you managed to get a new ECU fully working?

I'd be willing to take a look at your old ECU to see if it can be fixed. The throttle motor is directly powered from the ECU, it may just be the output stage of the ECU can failed. If there is an easy fix we can post up a repair guide for other members and you will have a full working ECU which you could sell.