95LS400Bob

I am trying to make a thread here for the many of those with low idle, engine quits after an extended highway cruise when coming to a stop, and a mysterious drivetrain jerk when you let off the throttle and get back on....sometimes...and usually happening over 40 mph.

My 95 Ls400 built april of 95 which now has 150,000 miles has these problems.
I've done full diagnostics. I've gone after the throttle body and the Idle control valve. All of which were working perfectly. After 3 days of reading threads at several different forums of similar problems with 95's, several emails and follow ups on who found what the problem was and how solved I wanted to put all the information here so the next guy could find it easier.
Some guys are driving around with the a/c on to keep the engine running at a faster idle to keep the car from dying.

I'm convinced all 3 problems are related to the ECM and it's controlling of the idle air control. While there were a couple of TSB's on this it was never a recall. Those of us who bought used or have high miles are out of luck for any dealer help...at least I would think.

Your Ecm is located behind the glovebox on the passenger side. If you want to read what number Ecm you have..you can do that by not removing it. Just remove the lower plastic panel below the glovebox and look up in there. You'll see "Engine Computer Label" and the numbers.

For 1995's:
Your original Ecm is either:
89661-50220 or 89661-50221 if Federal (49 state). Lexus new replacement on the TSB says to replace with 89661-50224

If California then your orginal Ecm is either 89661-50230 or 89661-50231. The TSB calls for 89661-50234
But searching a local Lexus parts site shows that number has been replaced with 89661-50235-85.

The cost of these Ecm's new is just total crazy. But there might be another solution.
One member bought a used pcm from a wrecking yard #80661-50224. He paid about $150 for it and it solved his issues. I did some searching in wrecking yards and there are some of these #'s out there.

If you have a California car then there seems to be few out there. Mine is a California car. I don't know if a 49 state Ecm will work...I suspect it will...but unknown at this time.

Another member bought a remanufactured Ecm for his 49 state car. He paid $300. for it and it has a 1 year warranty. He also stated that it cured all problems. The company he purchased it from was Auto & Truck Electronics in West Palm beach, Florida. He said the part number was #95 Int 56834. (That was a 49 state unit).

There are other places on the web where rebuilt Ecu's are sold. The problem is most are listed by the old number. We have no way of knowing if the old units are rebuilt and then "reflashed" to the later specs which we are looking for to solve these issues.
I'll try to find out about that and post here what I find out.

For 1996's: The Ecm you want is 89661-50303. Original's were 89661-50302. A wrecking yard buddy did a nationwide search and there are used 89661-50303's out there. Evidently these work in all 50 state cars.

Ps: A 1996 Ecm will not work in a 95. It turns the check engine light on. That's been tried.

Update: I just received an email from the gentleman who bought the remanufactured pcm from Auto & Truck Electronics(mentioned above). He confirmed with them that the Ecu had the latest software upgrade before he bought the Ecu. He also commented the car shifted smoother than it ever did. So I will be ordering one from them.

JBrady

Good research.

I would also suspect the throttle position sensor.

la013oi

im new here, well i have this problem too but it didnt start getting bad untill i installed an aftermarket intake on it...before it whould only happen once a month or not even at all but now it jerks every time i hit 60 and when i come to a stop it shuts off after a long drive. i have a 92 ls400 with 174,000 miles....is there another reason why it does this more now then with the stock intake. and will this happening to my lex damage my motor...i really need the help because i just bought this car and i dont want it going wrong on me......

95LEX400

I know it's a double post but it applies here too:

"got the car back today. Runs great and no hint of the stalling problem after prolonged freeway drives or the jerking during throttle tip in at cruise after extensive testing by the dealership and myself. They ended up replacing the ECU after trying a few other things that didn't work. I originally also had an additional high RPM miss that was fixed by changing the sparkplugs. The dealership even delivered the car 75 miles to my house and drove the loaner back.
It might cost a little more to get a clean used Lexus from the dealership but in my case it really paid off. They really stand behind these cars and have gained a loyal customer for any future Lexus purchases. If anyone is in the market for a used Lexus call Larry Gentry at the Lexus Store of Lexington 859-621-0391.
Sorry for the shameless plug but these guys really came through for me."