When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Do you now have power at the PSD? I.e., you were able to connect power to the pump motor and build up pressure in the collector in ~20 seconds and after that you were able to trigger the solenoid and bleed fluid at the PSD and the slave cylinder? Just not sure where you're at in your diagnostics.
Yes I did that for bleeding the system, although I was bleeding for approx 7 sec , than disconnect & than again manually powering pump & solenoid...
Have you cleaned the lateral acceleration sensor under the driver seat? If it is sending an implausible signal to the PSD control the system will be disabled. Remove the sensor, pop the plastic cover off and rinse with some electronics cleaner. Allow to dry completely and reassemble. The sensor contains a magnet. When enough ferrous debris collects on the magnet the field is able to capture the senor moving element. This will create a false signal.
Today while I turned on ignition my 30A fuse was blown. So I tried to replace the fuse & found that it blows everytime I turn the ignition on... So I started disconnecting wiring from PSD unit... Unplug solenoid connector wire, check fuse , it was blown... Than put new fuse, unplugged pump connector, again fuse blown...... Now when I removed the 3rd connector ( don't remember exactly it had 5/6 pin) fuse does not blow...
is my PSD unit internally short
Today while I turned on ignition my 30A fuse was blown. So I tried to replace the fuse & found that it blows everytime I turn the ignition on... So I started disconnecting wiring from PSD unit... Unplug solenoid connector wire, check fuse , it was blown... Than put new fuse, unplugged pump connector, again fuse blown...... Now when I removed the 3rd connector ( don't remember exactly it had 5/6 pin) fuse does not blow...
is my PSD unit internally short
The 5-pin connector is on the pressure switch, but none of those wires are fused by the 30A fuse. However that pressure switch does control the relay, which connects battery voltage through the 30A fuse to the pump motor. So if the fuse blows with the pump disconnected, and doesn't blow when the pressure-switch is disconnected (and the relay does not actuate), then there is a short to ground on the large (4.0mm) black wire from relay to motor. Pull the fuse, disconnect the motor, and check resistance to ground with a multimeter (ohms scale-- should be open-circuit).
The 5-pin connector is on the pressure switch, but none of those wires are fused by the 30A fuse. However that pressure switch does control the relay, which connects battery voltage through the 30A fuse to the pump motor. So if the fuse blows with the pump disconnected, and doesn't blow when the pressure-switch is disconnected (and the relay does not actuate), then there is a short to ground on the large (4.0mm) black wire from relay to motor. Pull the fuse, disconnect the motor, and check resistance to ground with a multimeter (ohms scale-- should be open-circuit).
Thankyou for the reply sir, I believe this should be what exactly wrong with the wiring..... I will check & update tomorrow....
I wonder if something happened to your wiring when your high pressure line was damaged/removed(?) That's probably the area I would start at and see if there's any gashes in the insulation/cord.
Today I checked the wiring for short, but the black wire does not has any short to ground.. the fuse is blowing when relay clicks, only when the pressure switch plug is connected regardless the connection of other 2( pump & solenoid)... Now I am thinking is it possible that a bad switch can cause this fault.... ?
it has 5 wires,I don't know how to check this switch ...?
I wonder how much a switch is? I dont thinks its part of a rebuilt unit, is it?
Pressure switch from Sunset Porsche is $539. Part #964-606-904-00. 928 Intl has it on their site for $229. I assume it's used but it doesn't have the "U" prefix. http://shop.928intl.com/Ss-To-964-60...06%2D904%2D00/
Today I checked the wiring for short, but the black wire does not has any short to ground.. the fuse is blowing when relay clicks, only when the pressure switch plug is connected regardless the connection of other 2( pump & solenoid)... Now I am thinking is it possible that a bad switch can cause this fault.... ?
it has 5 wires,I don't know how to check this switch ...?
The 30A fuse that is blowing is the power for the motor, which doesn't go through the switch. The fuse is blowing when the relay closes, and the switch is controlling the relay. But it is not the cause of the short-circuit.
Here is the wiring diagram (page 9 of the '93 wiring here, but they are all the same): The 12V high-current path to the motor is highlighted. The motor power comes direct from the battery on a 4.0mm red wire (the C83 reference to the next page). It goes through the 30A fuse to the relay. When the relay contact is open (as shown here) everything is fine. But when the relay clicks and closes, the fuse blows. Follow the circuit-- it goes to the motor, and then through the motor to ground. It doesn't go to the switch at all-- just the fuse, relay and motor. If the motor is jammed then the fuse will blow, but not instantly.
There is one more possible path to ground, and that is the diode inside the relay. That is there to protect the relay contacts. When the relay opens, the motor continues to spin for a moment and will generate current in the same direction. That current will flow through the diode from ground instead of arcing across the relay contacts as they open. But if that diode is shorted, then it will blow the fuse just like a shorted wire.
So if the wiring is OK, then the next step is to replacing the relay. Or take it apart and replace the diode, but if you listen carefully you can hear the chanting on the list: "relay, relay, relay ...". Just replace it, relays do go bad.
You can also try checking the diode with a meter, but that is sometimes difficult because of the low voltage that some meters use. If the meter has a diode-checking "beeper" function then you can try that. The diode should show 0.7v drop in the direction of the arrow, and open-circuit in the reverse direction.
The motor does run OK when jumpered direct to battery, correct?
Once the pump starts getting gummed up it puts major stress on the motor, which in turn creates heat and causes it to burn out. I rebuilt 2 PSD pumps this week and this is why it's so important to keep your unit serviced. Of the 4 we've rebuilt in the last month, 3 of them had motors that were shot, blowing fuses.
The 30A fuse that is blowing is the power for the motor, which doesn't go through the switch. The fuse is blowing when the relay closes, and the switch is controlling the relay. But it is not the cause of the short-circuit.
Here is the wiring diagram (page 9 of the '93 wiring here, but they are all the same): The 12V high-current path to the motor is highlighted. The motor power comes direct from the battery on a 4.0mm red wire (the C83 reference to the next page). It goes through the 30A fuse to the relay. When the relay contact is open (as shown here) everything is fine. But when the relay clicks and closes, the fuse blows. Follow the circuit-- it goes to the motor, and then through the motor to ground. It doesn't go to the switch at all-- just the fuse, relay and motor. If the motor is jammed then the fuse will blow, but not instantly.
There is one more possible path to ground, and that is the diode inside the relay. That is there to protect the relay contacts. When the relay opens, the motor continues to spin for a moment and will generate current in the same direction. That current will flow through the diode from ground instead of arcing across the relay contacts as they open. But if that diode is shorted, then it will blow the fuse just like a shorted wire.
So if the wiring is OK, then the next step is to replacing the relay. Or take it apart and replace the diode, but if you listen carefully you can hear the chanting on the list: "relay, relay, relay ...". Just replace it, relays do go bad.
You can also try checking the diode with a meter, but that is sometimes difficult because of the low voltage that some meters use. If the meter has a diode-checking "beeper" function then you can try that. The diode should show 0.7v drop in the direction of the arrow, and open-circuit in the reverse direction.
The motor does run OK when jumpered direct to battery, correct?
'93 GTS wiring, page 9
thanks a lot Mr. Jorseman,
you have done a tremendous job by highlighting wiring diagram & explaining things in easy terms...
My 1st relay was bad, which had open between terminal 85& 86( control side).. I installed a new normal relay( same no. of pins but not original)..... & It still blows... I will confirm if the new relay is ok.. by taking measurements as per your instructions...
& Yes motor works ok while jumping directly..
Once the pump starts getting gummed up it puts major stress on the motor, which in turn creates heat and causes it to burn out. I rebuilt 2 PSD pumps this week and this is why it's so important to keep your unit serviced. Of the 4 we've rebuilt in the last month, 3 of them had motors that were shot, blowing fuses.
Thankyou for the input Mr. SeanR.....
I operated the pump manually while switching solenoid.... The flow coming out was not very fast although it was smooth & continuous... Is there any way to know motor is shot ... ?
...
My 1st relay was bad, which had open between terminal 85& 86( control side).. I installed a new normal relay( same no. of pins but not original)..... & It still blows... I will confirm if the new relay is ok.. by taking measurements as per your instructions...
& Yes motor works ok while jumping directly..
That is not a normal relay-- and that may be the problem. A normal "53" relay has 4 terminals: two for the coil, and two for the normally-open (NO) contact. A normal 5-terminal relay is the same and adds a normally-closed contact. The PSD relay has the NO contact of the 4-pin, plus a diode to ground on a 5th terminal... So substituting a "normal" relay may be causing a direct short to ground.
I don't have a part# for the PSD relay, and it is not listed in PET. I'll try to find some info, or maybe someone here can come up with a part#. Mark?? Roger??
I don't have a part# for the PSD relay, and it is not listed in PET. I'll try to find some info, or maybe someone here can come up with a part#. Mark?? Roger??
02-05-2020, 11:27 AM
