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Has anyone jumped the relay for the ABS pump to make it run and remove air versus just taking it to the dealer and doing the Tech II purge?

If you have done this, which two terminals did you jumper?
 

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Discussion Starter #2
Are you telling me everyone does this with a Tech II?
 

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When you pull the relay there will be a small diagram on the side of it if you can read a schematic its easy to determine which cavitys to jump with a Fused jumper. The terminals are numbered on the bottom side of the relay just match them up with the fuse box.
 

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By the way the Tech2 purge function not only runs the pump but also opens the valves in the ABS valve block. You may not be able to purge all air from the brake system without doing the ABS purge.
 

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6SPDGTO said:
Are you telling me everyone does this with a Tech II?
I suspect the foregoing is a little strong. I did notice your question after I got to work this AM. 2 hours to go, I will crack my Helms' when i get home, it sounds at least possible, but I suspect FlFlash47 is correct.
 

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As drawn (p 5-115) the relay external to the Electronic Brake Control Module (EBCM) supplies 12VDC+ to both the valve actuation relay and pump actuation relay inside the EBCM. To get the valves to open and the pump to run (thus drawing clean brake fluid into the EBCM), you will need not only the 12VDC+ supply from the external relay, but also some kind of signal to close the internal relays so current can actually flow.

I wonder if HPTuners or LS1Edit can supply that signal? The EBCM is on both the secondary serial data bus (BCM, radio and IPC) and the ABS serial data circuit (apparently a stand alone line from pin 12 of the DLC to pin 12 of the EBCM connector, a BU/BK wire).
 

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Discussion Starter #7
swmn said:
As drawn (p 5-115) you will need not only the 12VDC+ supply from the external relay, but also some kind of signal to close the internal relays so current can actually flow.
I'm thinking, that jumping the relay while actually pushing on the brakes will cause it to cycle.

Can you ell where that signal normally comes from? Is it logic or something like the brake switch?

I guess my questions is, at what point does logic come into play. Logic being the wheel speed sensors, brake switch, etc. Does logic control the internal or external relays?
 

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I _think_ the external relay is going to power up as soon as the ingition is tuned to on/run without even starting the car.

Closing the internal relays, it looks like, is going to take logic. The schematic in the Helms for the inside of the EBCM is very general, probably the EBCM is not serviced at the dealer level.

I imagine the driver IC(s) for the pump motor and valve motor are just looking for a zero volt or 5 volt off/on command at pin #whatever.

Could it be that Rossi Pontiac has never done this and Dublin Motor Sports has never done this?
 

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Yes the relay is powered with the car as it is the main power supply side of the ABS system. What you really need to do is take the cable off of the ABS control unit and supply +12 volt and ground to 2 of those pins, and +5 to another set of pins to take up the signal from the computer to activate the ABS. I would need to look at the schematic for the EBCM pinout, and determine which pins, but how are you going to generate the +5 signal.

I would suggest purging the system once, then doing a panic stop to activate ABS, then purging the system again. It will be easier, becasue I think the Tech 2 is the only thing that will talk to the BCM (body control module) and the EBCM.

GTPrix: Does HPtuners or LSedit have the ability to talk to the other modules in the car, or just the PCM?
 

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Napalm said:
Yes the relay is powered with the car as it is the main power supply side of the ABS system. What you really need to do is take the cable off of the ABS control unit and supply +12 volt and ground to 2 of those pins, and +5 to another set of pins to take up the signal from the computer to activate the ABS. I would need to look at the schematic for the EBCM pinout, and determine which pins, but how are you going to generate the +5 signal.
8 of the connectors on the EBCM are the low reference and signal from each of the four wheels. It looks like internal logic. The brain inside the EBCM 'knows' how fast each of the four wheels is turning, and controls both the ABS (with the valving and pump motors inside the EBCM) and the traction control circuitry.

The EBCM can send a signal to the throttle relaxer. There is a dedicated pair of conductors, EBCM back forth to PCM, 'requested torque' and 'delivered torque'.

And the EBCM monitors the postion of the brake pedal.

I am sure you could bread board something up, but ultimately I think it will be more useful, more valuable, to find a Pontiac dealer who will actually do the work, rather than just bill you for it. Because then you have found a dealer you can visit again.
 

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Discussion Starter #11
swmn said:
I am sure you could bread board something up, but ultimately I think it will be more useful, more valuable, to find a Pontiac dealer who will actually do the work, rather than just bill you for it. Because then you have found a dealer you can visit again.
I'm starting to think that you are right. I used to have a dealer that would just loan me a Tech II for the evening but I don't have that connection anymore.

I've tried the bleed then make ABS work but that didn't instantly make them mushy again. However, doing another run to 140 did make them mushy again. I'll bleed them again and see what I come out with.

Did I mention how this started? I severely overheated my brakes on a road course. I believe I actually cooked the fluid as the brakes were pretty much useless until I bled them the first time and changed the pads.
 

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If you bleed the brake system clean, when you activate the ABS it should not make the brakes mushy again. Instead you may have a slight (tablespoon or less) amount of dirty old fluid now in the lines.

IE when you bleed again you should see a slight tinge of color, and then clean again. This fluid that is left over in the ABS valve body really won't hurt anything, also this fluid did not boil during your track day unless the ABS kicked in. Otherwise this small amount of fluid was trapped in the valve body behind a set of solinoid valves.

Again good luck
 

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Napalm said:
If you bleed the brake system clean, when you activate the ABS it should not make the brakes mushy again. Instead you may have a slight (tablespoon or less) amount of dirty old fluid now in the lines.
I have seen this idea a couple places in this section. It makes sense that activating the ABS is going to push X amount of dirty fluid from the ABS module into the lines, and suck the same X of clean fluid into the ABS module from the master cylinder.

Has anyone done this a second time to see if they get a second teaspoon of dirty fluid, or a third time? You know? How many times, how much brake fluid is that, to get clean brake fluid out of the ABS module?
 
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