Power steering motor doesn't get power

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Topic author
Nilsen
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Joined: 11/04/12 23:20

Power steering motor doesn't get power

Post by Nilsen »

Hi, I get fault code 11 on my power steering when I do the diagnostics.. The power steering pump doesn't kick in,, I have hooked the pump directly to the battery and then it turns on, so the pump works..

I have tested the relay that's usually faulty but it seems to work fine, I've tested it with 12v direct to the thinner wires and get continuity on the fat ones,, I've tried to bridge out the relay too and the pump still won't kick in..

I even borrowed the power steering ecu and driver from a friends car still no power to the pump

have anyone else had a problem with this and what did you do?? Thanks



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MR2DI4
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Re: Power steering motor doesn't get power

Post by MR2DI4 »

Have you got 12V power to the relay itself ?

If the pump works with direct 12V and the relay is switching and its still not working then the 12V to the relay itself is missing.

I found that the P/S is a common fault, its so random on my car occurring every 5 or so years that I put it down to a glitch in the ECU. I just disconnect the battery for a few minutes and the problem is gone.

Its not the relay, its a beast and can handle like 60 Amps. Got 2 of them in my car and neither of them have failed.

The P/S ECU simply doesn't switch the relay on.

Note that the relay is turned on by a "Low Side Driver" so one side of the relay is at 12V but the other side is switched to earth. If you have 12V on both side of the relay (the thin black and white wires from memory) then the ECU is not switching the relay on. That relay uses about 1.5A in the coil just to turn on.

Unplug the relay and put 12V direct across the coil of the relay does the relay switch and the motor run ?


Topic author
Nilsen
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Joined: 11/04/12 23:20

Re: Power steering motor doesn't get power

Post by Nilsen »

I will try on monday when I'm in the garage,,but I have my suspicions that the power steering sensor might be faulty. It's the only thing I haven't gotten to test as per the bgb test I can't do it as long as I have a fault code..

Btw If you see the pic I attached, I only need the black ring sensor (attached on the backside) for power steering to work, or do I need both black and yellow ring sensors??
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Topic author
Nilsen
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Joined: 11/04/12 23:20

Re: Power steering motor doesn't get power

Post by Nilsen »

when I put the thin black and white power direct on the battery there is still mo power to the pump,,, I have measured with the thin wires connected to the relay and than there is 5-6 volts when car is running and I don't touch the steering wheel,,as soon as I turn the wheel the volt goes up to 14 ,, but the thick wires is dead so the relay is definately not turning on,,could the steering sensor be the fault of this??

I have borrowed both power steering ecu and driver boxes from a friend and it was same problem with those..
I've even bought this relay https://www.mr2oc.com/threads/power-ste ... ap.355400/ and still same problem, doesn't turn the pump on,,,not even the 5 secs on startup before you start turning the wheel

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Re: Power steering motor doesn't get power

Post by MR2DI4 »

We seem to be getting this lost in translation it's really very simple.

When you connect the thin black and white wires direct to 12v then the relay made a loud click right ?

So then there is either an open circuit in the relay or it has no 12v to it on the thick wires that have nuts on them if the motor then doesnt run.


Topic author
Nilsen
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Re: Power steering motor doesn't get power

Post by Nilsen »

Yes, it makes a loud click when the thin wires get powered with 12v..

doesn't the power go from the thin wires through the relay and exit through the thick wires giving power to the pump/motor, if working properly?

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Re: Power steering motor doesn't get power

Post by MR2DI4 »

Nilsen wrote: ↑
22/07/20 2:01
Yes, it makes a loud click when the thin wires get powered with 12v..

doesn't the power go from the thin wires through the relay and exit through the thick wires giving power to the pump/motor, if working properly?
NO

The thick wires are the main supply to the motor. The thin wires are the control circuit from the ECU to the relay coil. Two totally different isolated circuits.

You have to have 12V on the thick wires all the time for the pump to work. This is the high current feed to the motor. If you short out the two thick wires on the relay then the motor should run, if it doesn't you have no 12V to the relay.

If you have already checked the motor runs with 12V direct to it then you have verified the earth from the motor is okay.

Sounds like you have no 12V on the thick wires and possibly the fuse is gone or a fuseable link is gone or there is a bad connection or melted connection.

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Re: Power steering motor doesn't get power

Post by jimi »

No, thin wires only energise the relay, power is then switched from one thick wire from the battery via a fuse to the other thick wire to the motor. Download the electrical diagrams from here https://www.mr2oc.co.uk/download-cats/c ... 1-mk2.html there's a section in there explaining how the EHPS circuit works.
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Topic author
Nilsen
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Re: Power steering motor doesn't get power

Post by Nilsen »

The problem with wiring diagram is that there are 2 different setups (as far as I know) and I can only find for the setup I don't have..

I have the pump setup where the blue wire loops in the plug (pic 3 & 4) and the wiring diagram I have for 1993 sw20 (probably american) shows the blue wire going from motor to power steering ecu (pic 1 & 2)..

My car is a 1997 jdm import
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