Toyota MR2 Power Steering System

Posted on Feb 5, 2014

Wondered how to control the MR2 Power steering pump so that it is not a noisy power hog because it ’s always on full throttle. Designing some sort of motor controller or using a small off-the-shelf controller would not work for me. One, I ’m not that great of a designer of controllers (I ’ll leave this up to Otmar). Second, a small of

Toyota MR2 Power Steering System
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f-the-shelf controller would not work on high voltage systems. Plus, I would have to program some type of Micro or Basic Stamp to get all the functions I want. So I decided to get the original motor controller from a MR2 at the junk yard and try to wire it up. Well, it works better than I anticipated. One of the modes of the MR2 controller is to slow the hydraulic pump to a stop when there is no movement of the steering wheel or vehicle road speed: saves power! I have also wired it to enable itself when the Zilla Contactor is engaged. I`m using the original steering wheel sensor from the MR2, so it senses how much steering I`m applying. It is also getting road speed info from the cruise control speed sensor to limit over-steer at high road speeds. It uses the sensors in the pump to tell you when the brushes are worn or overheated. The P. S. schematics provided are from a ’94 and ‘95 MR2, so try and get all the parts from a Toyota close as possible to these years. There are a couple different versions of the schematics here, so use the one that best suits your needs. 1. I used the original cruise control speed sensor for my ’85 S10 to drive the ECU and it has worked with good results. Your results or pulse rates may vary. 2. The ICT (PSCT) is a control wire for the main engine ECU to enable the P. S. when the engine is running. The P. S. ECU is disabled when this wire is brought low (grounded). So I used a micro-sized relay...

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