urben

I am completely new to the Lexus world and am feeling like a bit of a dummy. I've worked on my cars for many years, mostly with the aid of forum and youtube posts, but my wife's 2008 IS250 is stumping me. I've searched for quite some time on this forum and what feels like the entire internet, but nada, so here goes:

The car won't start, tried to connect an ODBII scanner and it won't connect. Tried another ODBII scanner and same thing. These scanners work on my other cars. Checked all the fuses everywhere and (skipping some steps here for brevity's sake) we figure it's got to be the ECU (aka EMU?, Engine Control Computer) and the next step is to replace that with a used one. My question, finally, is does the ECU need to be reprogrammed (for the key fobs, VIN, etc)? or is this a plug and play sort of deal.

MrHarris

iTrader: (1)

Is it your steering that's out? I have a 2008 Lexus IS250 steering ECU I just took out you can have. Replaced it with 2012 IS-F Steering ECU.

The steering ECU is located underneath the car battery. Check and see if theres any wires that melted.

urben

Thanks for the reply, MrHarris, but it's not the steering that's out. The car just won't start and I am unable to "talk" through the ODBII port with 2 known good scanners. I've also had a mechanic troubleshoot the car and he has narrowed it down to the ECU. Now, I just need to figure out how this whole ECU replacement thing works since I don't want to spend the $1000+ the dealer wants to do it.

Gville350

iTrader: (10)

What were the symptoms of the vehicle BEFORE this "ECU" failure? Is the fusible link still intact? Is the battery good? When you hit the start button WITHOUT depressing the brake, do all of the electronic work like they should?

urben

Foot on brake, start button pressed, green light on the start button, engine turns over, but will not start. It would do this a few times, then when the start button was pressed, all the gauges would jump around and do their thing, but it would not turn over. I charged the one year old Toyota battery and made sure the cells were full of electrolyte, same thing. I removed the battery for a few hours, then reconnected it. Same thing. I checked every fuse I could find and there were a considerable amount. We tried another fusible link from another Lexus (wife works at a body shop and the mechanic there had access to one), same thing. The check engine light does not come on. That's weird, eh? That and the fact I could not get 2 known good ODBII scanners to attach is what made us think it was the computer.

Thanks for all your help guys! Anyone ever replace their ECU and have to reprogram it? I think that's where we are, but if you guys have any more suggestions, I'm all ears.

minato

iTrader: (1)

Have you tried putting the shifter in N and starting it ?

LucianoLee

iTrader: (1)

So did the car crank when you try to start it? It sound like you said it did. Have you check the starter?

urben

The car is cranking. And cranking and cranking and cranking... well, you get the idea. :-) just not starting, even in neutral. 95% sure it's the ECU and was hoping someone with some knowledge or experience replacing one would be able to help me understand the necessary steps.

Gville350

iTrader: (10)

The ONE last thing BEFORE swapping out the ECU I'd check is if the shifter is truly in PARK. One time I read about a member that he couldn't get his car started, he ended up having to remove the cap over the safety release button on the center console and hit to release the shifter to access all gears. After he shifted through the various gears, and came back to PARK...he was able to start the car. Something about the neutral safety switch I guess.

If that doesn't help, then it just might be the ECU; would be the first one I've read about needing to be replaced. Boo!

andper10

There are many ECUs on these cars.

The smart access ECU handles key fob operation. If it needs to be replaced and you want to replace it with a used one, you will want to buy a used one with a key fob that is already paired (from the same model year IS250/350, and with the same FCC ID on the paired key fob as your current key fobs). Then you may be able to add your current fobs to the car with Techstream without reseeding the ECU (which takes more time (higher labor cost) and apparently requires the dealership to obtain and enter a code). But if the start button LED turns green with your foot on the brake pedal, I'm nit convinced the Smart Access ECU is the problem. It might be a different ECU that you need (or maybe just a replacement start button or part for the electrical, starting, or fuel system if you don't mind the OBD port not working).

Also if you haven't already, try connecting the OBD scanner when the start button has been pressed once (AUX) or twice (ON) without the engine running.

And try holding the fob right next to the start button when attempting to start the car and/or change the fob battery.

Might want to check the attached start button switch TSB to see if your VIN is in the potentially affected range.

Good luck with your investigation!

hirsch2is

Lexus and Toyota engine control computers usually have to be programmed to vin or you get a check engine light. Once they are programmed they are not able to be programmed to another car so you will always have an engine light. I haven't touched enough lexus vehicles but pretty much anything 2009 and newer Toyota I have replaced Ecu on needed a vin programmed are you positive you checked all fuses. The cigarette lighter and aux plugs fuse will usually power the old plug and most people skip it cause they figure it couldn't possibly be on the same circuit. And it is the most commonly blown fuse

hirsch2is

And if you didn't bring it to a lexus dealer for the diag that you mentioned I suggest you do. They have a plethora more info than 99% of aftermarket shops. It would be wise before trusting a shotgun diagnosis of a $1000+ Ecu.

4mula_J87

Good morning.... I think I’m having this issue also. My dash would light up but not starting. I replaced the P/S ecu under the u bee last year. Do you have to do anything if you just swap the ecu with another one? I link a small video to my YouTube page so y’all can better see the issues