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Power Steering using Toyota MR2 EHPS pump

223264 Views 72 Replies 39 Participants Last post by  remy_martian
Many EV conversions have to deal with Power Steering decision. If you decided to keep PS and looking how to drive PS pump, consider this all-in-one solution brought to you by Toyota engineers. Toyota MR2 has EHPS ( Electric Hydraulic Power Steering ) in which pump is driven by its own electric motor instead of pulley hanging off the main engine like most ICE cars do. First generation of MR2 had separate fluid tank, motor/pump assembly and controller, some EVers took motor/pump and wired it directly to 12V or via various switching circuits designed to keep the pump off while driving straight or at high speed to save power.

However, 3rd generation of MR2 also called Spyder has a single pump assembly combining motor, pump, fluid tank and controller, making it very attractive option for EV community.

To the best of my knowledge you are looking for 2000-2005 ( maybe some other years, I'm not sure ) EHPS pump from Toyota MR2 Spyder, call your local junk yards or check this one online . The pump looks like this:

Auto part Automotive engine part Automotive starter motor Carburetor Engine

To wire it use schematics below. If you don't have proper harnesses you can either solder directly or create your own connectors for each pin. I personally created connectors and then filled harnesses with caulk to keep wires in place. It can be removed later if needed.

Passive circuit component Circuit component Diagram Plan Technical drawing
Auto part Carburetor Automotive engine part Engine Vehicle

Although 50 Amp relay is stated, I couldn't find one so I used typical 40 Amp automotive relay, my testing shows that it doesn't actually reach 50 Amp current anyway.

You can wire VSS signal from your car to make the pump turn itself off at higher speeds, but I couldn't manage that because my Miata has unusual VSS signal. Even without VSS, the pump runs idle at 4 Amps until you actually turn the steering wheel, so the power wasted is very minimal.

You'd have to find a way to connect PS Pressure line from the pump to your car's rack and return line from the rack back to the pump. Return line is easy, just use 3/8 hose and clamps. As for pressure line, if you are lucky you can fit one from other Toyota models, if not, you can make custom one from separately purchased fittings and the pressure hose, I have seen those on Ebay and online shops like this one

Hope this helps, feel free to update this Wiki with more details, my main goal was to publish schematics and wiring, I am not very good with hydraulics, maybe someone can add details on making custom pressure hose.

Here are the Toyota part#'s for the electrical Connectors: These part#'s get the Plastic part only, The metal pin wiring parts are sold separately. Maybe someone can add the part#'s for those.
Part#'s Large connector 90980-12068
Middle connector 90980-10897
Small end connector 90980-10942

There are two part numbers for the wiring. They come with the plugs, rubber seals, & about 6 inches of wire. At $6.55/ea they aren't cheap for what you get, but they are made to fit.

Three pigtails for the small & middle connectors P/N: 82998-12440
Two pigtails for the large connector P/N: 82998-12500


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Do you know what adapter is needed for the high-pressure line?
This is what I'm using
Pegasus parts ( #3276-005 Male 16 x 1.5mm Metric Concave Seat to -6AN Male, Steel. Of course also a 16mm crush washer. I polished the edge of the pump provide a good seal. I've yet to turn the thing on so I can't say that it doesn't leak. Hopefully I'll know this weekend. If it works I'll add to the wiki.


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Dimitri, thank you for taking the time to post this very helpful information.
I have a question. I have a similar pump out of a 2005 volvo v50. The pump has only 5 leads, pos/neg end 3 other leads for "signals" from the host vehicle.
I have priced the MR2 pumps and have found that they are more expensive and harder to find. The volvo pumps are much cheaper and easier to find.
Can you point me in the direction as to where I could find info as to how to wire my pump?
Ill post a picture of my pump as well.
Thank you for any help.
Hey that's great to hear of another pump option. Best place to find wiring information will be the Factory service manual for the car it came from. Might be able to find it posted on the net or check to see if there are forums for that make model car. Let us know what you find.

Re: GM Hydroboost for brakes USING MR2 Power Steering EHPS pump

Hello Group I am starting my conversion, and I was wondering since the Gen3 MR2 pump is the best for Power Steering, is it safe to run the brakes off it using a GM hyrdoboost kit?
How do you measure safe? For me I think that is a hard question to answer. Since a failure at the pump still doesn't keep the car from stopping so not sure I would consider it a saftey question? However...

Does it work? I can answer that. In my conversion I am using a hydroboost from a mustang and a later model MR2 pump. Works great. People that have driven the car have actually been disapointed as it drives like a regular car. (the expect a EV to drive differently or somethign) I have the MR2 pump plumbed also into the power steering and hydroboost. Steering and braking feel is not noticably different from my ICE car.

I'll add this. The pump does make noise and mine is running all the time the key is on. When I brake hard it loads the pump a noticable amount. I'm considering having a shut down circuit or something so it turns off when not moving or something. I just love dead scilence when sitting still. When moving I don't notice the sound due to road noise etc.

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Now I am aware with the 3rd Gen P/S pump when you don't turn the steering wheel, the pump will not turn on...
That is from the circuitry in the MR2. If you don't have or wire in such sensors and circuitry well....
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