ABS Master Cylinder / Pump Assembly

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Ed Lijewski
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Re: ABS Master Cylinder / Pump Assembly

Post by Ed Lijewski »

Mirabile dictu! (wonderful to behold).

Re-read several recent posts above re my saga with ABS light On after installing new (remanufactured) wheel sensors on my 88 and my 89.

I've been driving my 88 exclusively the past few days. ABS light was always On. This morning I started the engine, shifted into D and gently began to roll forward...in less than a full wheel turn length I noticed the ABS light go Off.

I've not touched/tweaked anything ABS related since prior posts above.

I drove for just a few trips today, overall the system cycled Off with ignition Off and then On with ignition On after normal system self-check of ~5 seconds during maybe 5 starts/stops.

I can't explain it. I hope it continues to function normally. The brakes work okay when the ABS light is on, but the brake pedal action is higher and firmer with ABS boost.

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Re: ABS Master Cylinder / Pump Assembly

Post by brokencase »

It is very strange. I'm guessing it is a connection issue that finally resolved itself with seasonal temperature change.
Don't be surprised if it should act up again in the fall :)

Hey, I am curious as to the sensors the MPM is "manufacturing". I don't believe MPM manufactures anything. Are they exact like the originals? Is it possible he is using the Transit sensors I alluded to earlier? Does he offer the rears?

You can tell apart the originals from the Transit sensors easily. The original sensors have a metallic cylinder whereas the Transit sensors are all plastic.
See side by side pic I posted here:

Trust me Ed, the sensors are inductive. They are not Hall effect. If they were Hall effect then there would have to be at least three wires going to the sensor. In addition, if they were Hall effect they would not be tested for a specified resistance as the Helm's manual states 800-1400 ohms.

They are coils of very fine copper wire, many turns, along with a magnetic pole piece, just like an electric guitar pickup.
Instead of measuring the vibration of a guitar string, they measure the passage of teeth on the ABS ring gear.

FYI you can get Scorpio specific ABS sensors from Europe, several brands to choose from...
https://www.onlinecarparts.co.uk/car-br ... html#10106

But I am confident the Chinese Transit clone sensors will work fine, even though I have yet to to install them. Recall that I did install one into the hub and spun the wheel and saw the proper waveform on my portable oscilloscope.

Just waiting for my originals to fail...
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