Anyone any good with the electrical side of things, have found a job I want to get done on my car, so have been doing some research into it & sadly only have found a write up in the States for it. So I’m pretty sure I’ll be having a hard time getting getting the relay & circuit breaker here in the UK, anyway have a look at the circuit & if anyone can help, advise or suggest an alternative please do so many thanks, James
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Looks like the circuit breaker is a self resetting type.
Looking at the circuit - it\'s basically turning on the PS pump from a switch inside the car - which seems a little odd ?
My guess is the pump can trip the breaker quite easily - so a fuse would be useless in this circuit. The relay is quite a beast too - most standard automotive relays are rated upto 40A - so they\'d be no good here either. You want to find a spare \'main\' relay for a job like this - like the one on the passenger side bulkhead.
I\'m sure the standard pump in the FC/FD has a pressure switch and also a magnetic clutch to disengage the engine pulley from the pump itself when it\'s not needed. I wonder if whatever drives that logic could be used to switch the power relay on and off, and then just take it via a 100A fuse from the Main fuse distribution / battery positive. That way the pump is only on when the steering is used. The 100A relay is just to protect the wiring in the event of something going amiss with the pump.
Panel mounted circuit breakers are available here...
http://www.autoelectricsupplies.co.uk/product/286
And brutal relays are available here...
http://www.autoelectricsupplies.co.uk/product/177
All in the UK.:D
The circuit breakers are not of the auto reset variety but personally if something happens where it trips I\'d rather it stay tripped until any fault was rectified. It would be easier if you knew the power consumption of the pump-there would be a power factor calculation to take into account to allow for the initial surge when it fires up though. As long as your cabling is rated to you\'re protective device you can\'t go wrong-but make sure there is a seperate fuse for the smaller control cabling through that switch-just an inline blade fuse holder would do the trick.
if its a self contained unit and the ecu is with the pump unit then there would be no need for a switch inside the car. i assume from the description "hot in run" they mean only switched on when engine is running- to save the battery. on an fd you could run the relay via the alternator warning light circuit or even better go to any good tow shop like towsure and buy a smart charge relay, they are used for split charge on caravans and basically will automaticaly switch on when the battery volts rise above 13.0 volts- engine running. then you should be able to get a standard relay up to 70amps which will run your motor, they peak at around 60-70amps on start but run around 20-30 amps. try maplins online, i think a fuse would be ok for the motor - manufacturers use them and have no issues but i would measure the pump current draw loaded to be certain of what size to use personally. thought about doing it myself but ever convinced myself it would be worth the hastle. jon.
Thanks alot guys some great info & help!
The whole idea behind thie is to get me powersteering in the FC but can\'t use the standard pump as I have a Renesis engine in her, which means I also have no speed sensor to tell the powersteering when to cut out & don\'t wanna be running a pump with it on full power all the time as it would be dangerous on the motorways & high speeds. So the idea of using the electric MR2 pump is I want have to mess about with pulleys & the idea of the switch is to be able to turn the pump off at high speeds.
i wonder if you could use the speedo signal as an input for the speed signal. either that or a hall effect sensor and pick up mounted on a drive shaft- thats how my old sat nav got its speed signal, an alpine in dash system i think it was. a dash switch seems a bit hit and miss. i think i woulds start with measuring the output to the speedo head if its electronic and see if thats anywhere near.
I agree with Jon, I would avoid using the switch for that method of control if you can. Tricky one though, I don\'t know if there is a centrifugal switch that will make/break at a specific speed? Or like Jon said a Hall effect sensor, but then you need something to process the information that the sensor is offering. I\'ll have a browse see if I can find anything.
the pump will already have an input on the ecu for a speed signal, the hard part would be finding out exactly what infomation its looking for and recreating that info, those type of sensors are typically 0-5 volt with a working range of 0.5 volt - 4.5volt. i dont think you will need an exact match just something in the ball park on an older sytem like the mr2. an abs sensor and home made pick up might well do the trick. jon.
Looking at the stock circuit - it\'s a stepper motor controlled by the vehicle speed pulses - there is a small ecu - somewhere in the passenger footwell or behind the glove box, that controls the stepper. The stepper is just a valve regulating the amount of pressure - and hence steering effort - so the stock system is speed variable.
If you just go with a on/off switch - you\'ll get a much more abrupt change in steering feel. It might be possible to use the valve from the current PS pump with the electrical pump - then you just need a mechanism to turn that on and off.
For the power steering pump - it only needs to be on when you\'re turning - so maybe take a signal from the turn signals canceller unit - it feeds a signal to the indicator switch to trip the motor that resets the switch - the opposite of that signal could control a pump motor maybe ?
Found this in my searches :
http://www.evalbum.com/tech/mr2_powersteering.html
Seems the toyota PS pump is speed controllable, might be worth trying to get hold of the PS ECU from an MR2 as well then :)
Not sure what format the steering sensors have - but the FC has a steering angle sensor (variable resistor) which might be adaptable.
what about an early saxo system, much more common so should be cheaper from scrappys,and its a one lump deal ecu and pump in one. thats the one i was looking at. nice basic system. again speed dependent and so need some sort of speed input. what type of air flow sensor does your fc have- i think they are the old flap type so the output on that might poss work. the only thing i think i found on my fc which was a year newer was the ecu inputs where 0v - 7.5v and not 0v - 5v like all modern systems but it was a few years ago, you might want to double check that on yours. the other easy fix might be to run a feed to the speed input on the ecu through a variable resistor and just have a play, that way you might find a fixed point that is usable across the range, just bear in mind the pump wont like running flat out for long periods.or dash mounted you could tweak it for in town. i think you have a nice little project here and good luck, wish i could give you some hands on help. jon
sorry if i am being dumb but have just re read your post. you had power steering before? and done an engine swap. in which case you should have everything already there.. i have just had a quick skim of an old diagram for the fc and it shows a speed pulse in a 17 pin plug behind the dash going to the inst. cluster. The car already has an ecu/control unit for the power steering and if you have the oe rack still on it should have the pressure switch as well. whats the details of your car- i have a 1988 fc diagram, but someone on here must have whatever years yours is then if you need a little help with reading it give me a shout at
jon103a@googlemail.com (jon103a@googlemail.com)
jon.
if I am not careful I amy well end up being accused of being a salesman for Atomic, but, it might be worth giving him a call. he has developed an elecric power steering system for his manual racks, but could possibly used for your set up as well? even if not he should be able to point you in the right direction.
how much commision do you get i could use some extra cash, lol. jon