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Discussion Starter #1
Took truck into the shop for the abs light and brake light coming on and saying service brake system. They determined that the ABS Modulator Valve needs replaced and quoted me $640 plus an additional $150 to flash the ebcm and ecm once done. I found the modulator valve on rockauto for $134, and would like to just replace myself. I generaly do all my wrenching on my vehicles but I am unsure on replacing the modulator as I have heard that to bleed the brakes after replacing the modulator you have to use a tech 2 to be able to acuate the valves in the modulator while bleeding. Has anyone heard of this? Or had to replace the modulator?
 

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ok well which part are you replacing? The actual hydraulic portion, with the valves in it? Or the top part, with the electronics in it?

If you are replacing the bottom metal part that the brake lines go into, yes, you'll need to do an automated bleed procedure with a Tech 2.
 

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Yes I am replacing the hydraulic portion, the modulator. I have already replaced the ebcm on the top. So it looks like I am stuck having the shop do the repair as I don't own a tech 2.
 

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you can do the repair, and then just take it to the shop and have them do an automated bleed.

If you bleed the brakes manually "the old school way", they will work fine and feel normal. BUT if you slam on the brakes and the ABS kicks in, air will suddenly enter the system (as the solenoids and valves open/close) and the pedal will drop to the floor and you could lose your brakes.

So if you replace the BPMV, bleed the system normally...then just carefully drive it to a place that has a Tech 2.

You can kinda "ghetto bleed" the BPMV without a Tech 2, but its obviously not desirable/correct.

To do that...bleed the system manually so the brakes feel fine. Then go find a long straight dirt road (or snowy road, or something thats slippery), get up to speed, then slam on the brakes so you get a good long several-second-long ABS activation. The brakes will then feel really spongy, like theres air in them (because there is).

Go back and then bleed them manually until they feel good again. Then go out to the road and get ABS to kick in again. Then do it all over again.

That will probably get you 90% of the way there to what a Tech 2 will do during a real automated-bleed procedure as far as getting all the air out of the BPMV. You will know when you've gotten all the air out of the BPMV by how the pedal feels during an ABS event. If all the air is out and its properly bled, when the ABS kicks in, the brake pedal should not drop to the floor, it will stay firm and push back at you.

ben
 

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Discussion Starter #5
Hey thanks for the info! How do I releive the pressure on the brake lines when disconnecting the BPMV? I assume that they are pressurized.
 

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Hey thanks for the info! How do I releive the pressure on the brake lines when disconnecting the BPMV? I assume that they are pressurized.
only when you're pressing on the brake pedal.....

if they were pressurized all the time your brakes would never release.
 
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