GS - 2nd Gen (1998-2005) Discussion about the second generation GS300, GS400 and GS430 (1998 - 2005)

Modify steering ecu DIY

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Old 02-10-12 | 11:46 AM
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Default Modify steering ecu DIY

After reading all the posts about loose steering on the highway i was looking around for a newer version of my steering ecu.I have a gs400 and it came with the steering ecu 89650-30570.

L-tuned steering ecu's are not available anymore and the newer model ecu's are not easy to lay a hand on here in europe. So why not make a tuned steering ecu yourself.

In the attachment is a pdf with instructions how to modify the steering ecu with a simple 10Kohm potentiometer. Really cheap and great satisfaction.


Just in case... Mod is at your own risk!
Attached Files
File Type: pdf
Steering ecu.pdf (90.5 KB, 1320 views)

Last edited by jjm1975; 02-11-12 at 04:46 AM.
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Old 02-10-12 | 01:53 PM
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What does this do?
Old 02-10-12 | 01:58 PM
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Originally Posted by justablkv8
What does this do?
I imagine it makes the steering feel better and more responsive.
Old 02-10-12 | 02:08 PM
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Originally Posted by justablkv8
What does this do?
The same as a L-tuned or post 2002+ steering ecu does...

Last edited by jjm1975; 02-10-12 at 02:18 PM.
Old 02-10-12 | 02:20 PM
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hmmm not to be debbie downer but how do we know this wont just fry your ecu and what do you have to prove this is the same as the L-tuned,S.D. or gs430 steering ecu?

heads up to the US guys... the l-tuned ecu is supposed to be very similar to the GS430 OEM steering ecu and the S.D. steering ecu is also supposed to be similar
Old 02-10-12 | 02:55 PM
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I have GS430 so does that mean that my steering ecu is similar to L Tuned ecu? Is there a big difference between OEM GS430 and L Tuned ECUs or it's very minor?
Old 02-10-12 | 02:56 PM
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Originally Posted by jjm1975
After reading all the posts about sloppy steering on the highway i was looking around for a newer version of my steering ecu.I have a gs400 and it came with the steering ecu 89650-30570.

L-tuned steering ecu's are not available anymore and the newer model ecu's are not easy to lay a hand on here in europe. So why not make a tuned steering ecu yourself.

In the attachment is a pdf with instructions how to modify the steering ecu with a simple 10Kohm potentiometer. Really cheap and great satisfaction.


Just in case... Mod is at your own risk!
Sounds very cool and very doable!
Old 02-10-12 | 03:09 PM
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Originally Posted by sakataj
hmmm not to be debbie downer but how do we know this wont just fry your ecu and what do you have to prove this is the same as the L-tuned,S.D. or gs430 steering ecu?
Google(Where someone did this before just in a different way (http://autospeed.com/cms/title_Modif...8/article.html) and logical sense. The only thing the steering ecu does is sending a voltage to the solenoid valve on the steering rack and this voltage varies regarding to the speed you are driving.

On the board is a empty spot with a potentiometer symbol at the left side of the standard resistor. I don't have a prove but i guess its there for test cases. I de-soldered the standard resistor and readout its resistance. Then dialed the potentiometer in at the same resistance and soldered it in place of the old resistor. Nothing will fry in this situation because i created the same resistance with the ability to adjust. Then i slightly dialed in a lower voltage (± -0,06v) mentioned in a TSB (as a pdf attached).

Result is a more heavy steering wheel and no nervous highway miles anymore...
Attached Files
File Type: pdf
L-ST001-98.pdf (25.7 KB, 803 views)

Last edited by jjm1975; 02-11-12 at 01:30 AM.
Old 02-10-12 | 03:14 PM
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Originally Posted by krispl
Sounds very cool and very doable!
https://www.clublexus.com/forums/gs-...ering-ecu.html

You could check what kind of ecu you have:
9/97-1/02 = 89650-30570
1/02 + = 89650-30610
SportDesign = 89650-30600
Old 02-16-12 | 12:56 AM
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Great find. I'm going to look into this.
Old 02-16-12 | 06:22 AM
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Great find, But you can also order the Toyota Aristo JZS161 from Japan.
Old 02-16-12 | 06:54 AM
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Originally Posted by jjm1975
https://www.clublexus.com/forums/gs-...ering-ecu.html

You could check what kind of ecu you have:
9/97-1/02 = 89650-30570
1/02 + = 89650-30610
SportDesign = 89650-30600
I am going to do this mod and I purchased a second ECU (just in case I mess up something...)

It's a 89650-30560. Is it any different from the 30570??
Old 02-16-12 | 07:23 AM
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Originally Posted by YviE
It's a 89650-30560. Is it any different from the 30570??
I dont know exactly, but from what i read of totodiy the 30560 is used in the european spec gs300 and 430 through all the years...
I also dont know to which ecu it can be compared... Lets find out!
Old 04-19-12 | 02:49 AM
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Some pictures for this thread!

Power Steering ECU:


Removed the stock resistor and soldered in 2 wires:


Soldered a 5kΩ potmeter on the 2 wires:


Made a little hole in the housing for adjustment:


Haven't tried it out yet.
Old 04-19-12 | 08:27 AM
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^ thats awesome, post a review?


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