Simple circuit for an ABS valve body bleeder. No need for a T90P-50-ALA
Iíve put together a cheap and easy ABS brake bleeder circuit for us! After pouring over the electrical schematics and finding a nice source online (I will edit and give credit due to them when I find it again), I found it pretty easy to do. All you need are two cheap switches and some wire. The pump motor, relays, and valves/solenoids are all ground switched. Attached will be a quick schematic of what I used and Iíll write a description below in case the attached image disappears or someone wants more info. Feel free to modify it or let me know of changes and Iíll update it. I have not seen the insides of the T90P-50-ALA but imagine it does about the same thing, minus a microcontroller to handle the automatic timing of the motor (we all can count to 20 and 60secÖ).
This is designed and tested on my 1996 TBird, 4.6L, with traction control
1) Disconnect connector to ABS control module (55pin connector in driverís side wheel well)
2) Pins 1 and 19 are grounds. You only need one of them. Connect either one of them to one side of each switch.
3) To activate the pump (via its relay) and main ABS relay (under hood), from the other side of the first switch, run wires to pin 15 (pump relay) and pin 34 (under hood main relay). Side note: you can jumper 1 to 15 (or 19 to 15) at any time to run the pump motor. The key doesnít need to be on. However, the key needs to be on RUN for the main relay under the hood to activate (needs to be activated to open OUTLET valves). Thatís it for switch 1
4) Switch two needs four outputs going to pins 2, 18, 21, and 36. These are the OUTLET valves/solenoids within the ABS valve body. The INLETS are always open so you do not need to mess with them at all. So switch two is simply; ground coming in one side and four leads out to the four outlet valves. Thatís it!
I put the two switches in a crappy box to make myself feel better. Then hooked up all the wires (with the key off). Then with the key in the RUN position, I activated the pump switch, waited 20 seconds and then pressed the valves switch to release the trapped air. Remember, you can get the pump to run without the key on but the main relay (under hood) with not ďswitchĒ without the key on. Meaning, the valves will not open without the main relay. Thought my design was flawed until I realized I simply forgot to turn the key onÖ Ford service manual says their T90P-50-ALA runs pump for 20sec., then press valve button for 20sec., and then let pump run another 20sec. after you release the valve button. I donít like rules so I pressed the valves open and closed a few times while not counting.
Future modifications: I have not added control to the traction control OUTLET valve yet. I was more concerned with getting this to work and getting my car moving again. That valve is virtually the same as the other valves so an extra (5th) wire to pin 40 may be all that is needed. Without seeing the inside of the ABS valve body, Iím not sure if it really is necessary to have, put on a different switch, or clump it with the other OUTLET valves on the same switch. It would be easy to put all this on a ďtimedĒ circuit, if you so desired. The ground switching in this circuit only has to supply a signal to the relays so it doesnít need to handle the high current sides. Again, I am open to ideas. Enjoy!!
Trust me. I was almost a doctor once.