I may have to replace my ECM to remedy my auto trans shifting issues.

If I order just the ECM 89661-50781, do I need to do anything with my current SmartKeys to be able to start the car? I'm finding random posts in Google that indicate I might have to order new keys too and maybe have them programmed to the new ECM.

If anyone has gone through ECM/ECU replacement on a SmartKey LS, please let me know what was needed to make it all work.

Also if anyone knows of a place to order an ECM for less than $1300, (maybe a used one with the keys?), please let me know.

AN

 

i am pretty sure if you order a new ecu from lexus it will come with 2 keys and a valet key
if used i dont know.

 

on the toyota side. it doesnt come with new keys and needs to be programmed to the car.

 

Anyone want to break the tie? I think I'll give MyLparts.com a call and see if they know.

@jimbosr1 Do you know if the new key(s) that comes with the ECU would need to be "programmed" to the car/ecu or is it already setup for the new ECU?

Guess I need to find the ECU replacement part of the repair manual. That might clear some things up.

AN

 

the new keys wouldnt need to be programed.the keys would have to be cut for your locks from your old key i believe.

 

if you lost all your keys with the smart system you would have to get a new ecu.you need a master key to program a extra key.
if you could program a spare smart key without a master key,these cars would be pretty easy to steal.

 

I would just be sure the transmission issue is really the fault of the ECM. Did a technician give you that diagnosis? You might want to get a 2nd opinion.

A hard shifting transmission being a faulty ECM on an LS430 is a problem I've never heard of, I don't think there's a single poster that has ever had that issue.

Just don't want to see you throw expensive parts at a problem.

 

No technician. I was going to take it to the dealer until I realized they don't have an open timeslot for 2 weeks. I've actually found 2 or 3 places (along with the troubleshooting guide in the repair manual) that state the exact same thing I have. Harsh 2-1 downshifts, no codes, replace ECU.

See my post here: https://www.clublexus.com/forums/ls-...o-1st-2nd.html

AN

 

This looks hopeful:





Jeff at MyLParts was reasonably sure that you can use the current keys with the new ECM. The image above seems to concur.

 

Be sure that it is not the transmission control module. Most cars, there is one for the motor and one for the transmission.

I'm not sure, but if it is a separate transmission control module, I'll bet they may re-flash it. First, I'd buy a used one.

 

Trans is controlled directly by the ECM.



I would go the dealer/possible reflash route if it wasn't a two week wait just to get in to see them. I may hit up a couple of other shops that say they do Lexus before I order an ECU. I cannot find a used one so far, and to be honest, it's worth it to me to get a new one and be done with it.

 

that would be outstanding if you can use your present keys.

 

I think you may be misreading the flow chart. It says

"If a normal code is displayed during the diagnostic trouble code check although the trouble still occurs, check the electrical circuits for each symptom in the order given in the charts on the following pages and proceed to the page given for troubleshooting."


Have you checked the electrical circuits?



It THEN says

"If the trouble still occurs even though there are no abnormalities in any of the other circuits, check and replace the ECM."


To me, that says to replace the ECM only after all the circuits has been diagnosed. I think you may be skipping directly to this final step.



Just seems crazy to me to throw a guess on a $1,300 ECM and possibly other fees like programming the smart keys, flashing the VIN info etc before getting its properly diagnosed.

Even though a flow chart may seem to point to that, I don't think a single LS owner on this forum has had to replace their ECM over a transmission shifting issue.

There has to be other indie Toyota/Lexus service places that could do this level of troubleshooting.

This could be a grounding or wiring issue from the last car wash, that's when you said the problem started, the ECM could be fine. Or it could be a single solenoid that simply needs replacing.

Again, I would just hate to see an expensive part thrown at it until everything else was ruled out.

 

See my other thread. I have checked the circuits. Also, if a solenoid sticks or goes bad, the system will throw a code pretty darned quick. My primary concern is if I take it to a shop with no codes, they are going to throw parts at it. I can do that without their help. My 2nd concern is they will want to swap in a new trans.

Here are a few links I've found regarding hard 2-1 downshifts (they all end up with replaced ECU as the fix):
https://www.scribd.com/doc/295779954...B60-Comparison (page 62)

https://www.clublexus.com/forums/gs-...-a-stop-2.html (Post 25 and on)

https://www.clublexus.com/forums/gs-...and-1st-2.html (Post 23)

There is also this semi-weird web page. The description of post #6 (2005 Lexus LS430 105,000 mi, Visitor) seems too detailed to be made up: http://repairpal.com/poor-shift-qual...low-speeds-550

There is also this TSB for the GS300 which uses the A761E as the LS. http://valvebodypros.com/assets/a960_harsh-2-1.pdf

 

Clearly, thats why you're skipping to replacing the ECM because you can't get an appointment at the dealership.

It's an expensive guess.


I don't think it's your ECM, but let us know when you replace it.