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ABS Issue/Anti-Lock Light

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    ABS Issue/Anti-Lock Light

    Hi All,

    Anti Lock light behaves normally on startup but kicks on intermittently/randomly during a drive when either of the rear sensors are plugged in. It doesn't seem to have rhyme or reason behind it. I've been driving around for a couple days with front sensors unplugged trying to figure out what behavior might trigger the light but no luck.

    Unplugged all the sensors and did spin test - Both front sensors set the light off and both new rear sensors do not. So this is what I'm working with -

    Two new GKN axles with abs rings
    Two new rear abs sensors
    Two abs modules (1 came with car, 1 in stock)
    New ABS Relay under dash
    New Speed Sensor in Differential

    Checked resistance on both rear sensors and got 1.08 ohms. I did not buy them for this problem, they are about two months old, but not sure how new OEM sensors that ohm out could be the culprit here. Replaced the relay and the module under the dash for under 40 bucks...Same behavior.

    Time to tap into the knowledge-base!!!

    From what I've read over the past few hours there isn't much to this. I have carefully examined all wiring underneath the rear section of the car for damage. I also inspected wiring to the pump under the hood, all looks pristine. There are two relays on the ABS pump itself but I don't see how they could be causing this. Signal from sensors go straight from sensors to module under dash. If the light turns off after starting it up but doesn't kick on from spin test then the module isn't getting a reading from the sensors. Do I need to buy two new sensors (again?) I pulled them from the hubs to take a peek and they look perfect. EDIT: I have successfully tested continuity and resistance from the connectors under the rear seat all the way to the large female connector for the ABS module under the dash.

    Just to pose a couple questions - Is there any component to this system that I might be missing? Or something in the innerworkings of the rear hubs that might be causing the sensors to get no reading? Could I have mucked something up during my recent bearing and axle replacement (this is how I ended up with two new sensors, pressing out the old wheel bearings without removing the sensors)? I did do the spin test after replacing the sensors and the test was successful at that time.
    Last edited by E30Bastard; 08-13-2019, 09:19 PM.
    "It wouldn't be there if it wasn't..." - Milton Berle

    1988 325iS - M20

    Buy two new sensors it is... Sent from my Pixel 2 XL using Tapatalk
    "It wouldn't be there if it wasn't..." - Milton Berle

    1988 325iS - M20