Attesa Pump/press. Switch/solenoid Interaction Question

[amerlo]

Hello all,

I have searched this topic quite a bit and looked through the FSM, but I cannot find a the answers I am looking for.

I have transplanted the running gear out of a GTR32 into my S14 240sx and am having trouble finding out exactly how the attesa pump, pressure switch, and solenoid work together to produce X amount of line pressure. Since I do not have the attesa computer or sensors, my torque bias will be set manually to a certain front torque percentage, but only be engaged under certain conditions. Don't want to burn up that transfer clutch pack.

Even after looking at the diagrams in the FSM and reading through countless 4wd threads, I still do not understand how all 3 of the aforementioned components work together. My limited understanding is this and please correct me if I am wrong:

1. The pressure switch tells the pump to operate to maintain pressure until it is closed.

2. Voltage to the solenoid determines line pressure and therefore front torque bias? If so, how does it perform this? Does it change the amount of pressure that engages the pressure switch?

I suppose my main question is how the pressure switch is controlled. If I know how to change the amount of pressure that the switch engages at, I will know how to adapt the system to my car.

[godsmind]

1. The pressure switch tells the pump to operate to maintain pressure until it is closed.

2. Voltage to the solenoid determines line pressure and therefore front torque bias? If so, how does it perform this? Does it change the amount of pressure that engages the pressure switch?

Hi There.

Im doing the same conversion on my S15 at the moment. Just gathering all the parts now. But I have went though the whole circuit I might be able to give you the answer you are seeking.

1. The pressure switch tells the pump to operate to maintain pressure until it is closed.

The Main Atesa pump is opperated by an relay which is controlled by the accumulation unit switch. Which means, once the fluid presure in the accumulation unit had dropped under a certain level, the swich inside will send signal to the motor relay to start the pump again in order to raise accumulator presure. If the accumulator is faulty or leaky, the relay will keep ticking as alot GTR owner experienced, this is due to the accumulator is unable to maintain the fluid presure.

2. Voltage to the solenoid determines line pressure and therefore front torque bias? If so, how does it perform this? Does it change the amount of pressure that engages the pressure switch?

As for the solenoid. Solenoids are controlled by current as you may already konw about. The current goes though the solenoid and activate the valve to a certain leve. If you have a look at the circuit diagram, one end of the solenoid is connected to the battery volvate, the other end is connected to the E-TS controller.

Now (as I am believe), during normal opperation where the car is running as RWD, the solenoid end where is connected to the E-TS controller should be Battery Volate, there for no current is being drawn into the ECU.

When the car requires certain amount of torque, the controller will control certain amount of current going though the solenoid there for the line presure is controlled. Thus, the front torque is controlled.

If anyone believe this is wrong, feel free to correct me . As I will have to start on my convertion this month or two.

Cheers.

[amerlo]

Hi There.

Im doing the same conversion on my S15 at the moment. Just gathering all the parts now. But I have went though the whole circuit I might be able to give you the answer you are seeking.

1. The pressure switch tells the pump to operate to maintain pressure until it is closed.

The Main Atesa pump is opperated by an relay which is controlled by the accumulation unit switch. Which means, once the fluid presure in the accumulation unit had dropped under a certain level, the swich inside will send signal to the motor relay to start the pump again in order to raise accumulator presure. If the accumulator is faulty or leaky, the relay will keep ticking as alot GTR owner experienced, this is due to the accumulator is unable to maintain the fluid presure.

2. Voltage to the solenoid determines line pressure and therefore front torque bias? If so, how does it perform this? Does it change the amount of pressure that engages the pressure switch?

As for the solenoid. Solenoids are controlled by current as you may already konw about. The current goes though the solenoid and activate the valve to a certain leve. If you have a look at the circuit diagram, one end of the solenoid is connected to the battery volvate, the other end is connected to the E-TS controller.

Now (as I am believe), during normal opperation where the car is running as RWD, the solenoid end where is connected to the E-TS controller should be Battery Volate, there for no current is being drawn into the ECU.

When the car requires certain amount of torque, the controller will control certain amount of current going though the solenoid there for the line presure is controlled. Thus, the front torque is controlled.

If anyone believe this is wrong, feel free to correct me . As I will have to start on my convertion this month or two.

Cheers.

Just to reiterate: The amount of current running through the solenoid determines the pressure at which the pressure switch closes, thereby stopping the pump?

[godsmind]

Just to reiterate: The amount of current running through the solenoid determines the pressure at which the pressure switch closes, thereby stopping the pump?

Hum..The pump is not controlled by the solenoid.

Go back to point 1, The pump is controlled by the an eletrical relay which stop starts the pump.

If you have a look at the hydraulic diagram, the pressure between the pump, accumulator and entrance of soenoid are at the same level. Once the accumulator's pressure (Pressure switch in here) had dropped to certain level, the pump will start again in order to bring the pressure up to the desired level.

On the otherhand, As you written, The amount of current running through the solenoid determines the amount of presure being released to the tranfer case. BUT THE SOLENOID WONT STOP THE PUMP as the pump is controlled by the pressure switch.

Is it clear now?

[amerlo]

Hum..The pump is not controlled by the solenoid.

Go back to point 1, The pump is controlled by the an eletrical relay which stop starts the pump.

If you have a look at the hydraulic diagram, the pressure between the pump, accumulator and entrance of soenoid are at the same level. Once the accumulator's pressure (Pressure switch in here) had dropped to certain level, the pump will start again in order to bring the pressure up to the desired level.

On the otherhand, As you written, The amount of current running through the solenoid determines the amount of presure being released to the tranfer case. BUT THE SOLENOID WONT STOP THE PUMP as the pump is controlled by the pressure switch.

Is it clear now?

Well, I suppose what I was trying to say was that once the pressure switch is triggered, it sends a signal to the attesa ecu, which in turn cuts the power to the pump relay.

I did however take apart the some of the pump components to see how they work. With your pump on the right, looking down at the top of the assembly, working from right to left: you have the pump, a large black cylinder (unknown purpose), and then the pressure switch (small black cylinder with 2 leads. Then underneath the pressure switch is the solenoid (medium gray cylinder with 2 leads). I haven't taken the piston assembly that the solenoid engages, but I now see how the solenoid controls how much pressure is fed to the transfercase actuator. It either has full pressure with no current to the solenoid or full. As I said, I will have to take the piston assembly apart at some point to clarify.

Do you know what the black cylinder in between the pump and the pressure switch is?

Edited March 3, 2010 by amerlo

[godsmind]

Do you know what the black cylinder in between the pump and the pressure switch is?

It is the accumulator, it stores the pressurised fluid in there.

[amerlo]

Ok, I should have gotten that based upon your other posts, but that was what I thought its purpose was.

Now, I would need to look at the pump assembly again, but the pressure to the transfer case must be released via the return line once the solenoid de-energizes.

I suppose that you plan on running your own control device without the Attesa ECU. Is that correct?

[godsmind]

Sweet, now you have somewhere to start with:).

For myself, I will start off with a R34 V spec ECU first, just to get it going as I still don't know what the computer with different inputs. I am sort of thinking putting a PLC between the ECU and the solenoid; that way I have full control of the 4WD system by changing the parameters in the PLC, which will act like an aftermarket engine ecu; but that is long way fancy plan. I have brought a R33 V spec hydrualic pack cheap and taking the risk that it will work with the R34 ecu (R34 Vspec one is quite expansive). The only thing might be different between the two would be the solenoid coil energizing current. Other than that I am sure the hydraulic circuit would be identical. I haven't got it yet, once i have it, All i have to do is to check the Ohm reading on the solenoid against the ohm specification on R34 sup manual. If they match, I will be laughing!!

What are you putting into your rear sub frame? putting the whole GTR frame in seems to be a bit of too much work. My plan was to swap both front and rear. I know front you cant get away from, not sure there is a short cut with the rear.

[jamind]

Hi you have got the two computers that are located in the boot up under the parcel tray i for the pump and the other cant remember ill check it and get back to ya. Jamind