Weird symptoms of faulty ABS sensor

[anthonym]

For long and convoluted reasons that I'm not going into, I recently installed replacement used rear ABS sensors in my 98 type V MR2. These worked OK but I assume one had a break in the wire as every so often the ABS light in the dash would flicker on. That would be OK and understandable, only that as well as the ABS light flickering on, the rev counter needle would oscilate wildly and the engine would stumble . This did not happen with both rear ABS sensors unplugged (ABS light on constantly) and, now that I have replaced the faulty sensor, appears to have been fixed entirely. Basically I'm intrigued as to what would cause this, anybody know? The only expnanation I can think of is the intermittent sensor connection was causing the car to flicker in and out of some sort of limp mode.

[event2]

check you earths onto your battery we had a car at work that the tacho needle would go up and down and lights on dash would go on and off randomly and it had a seperate earth wire for dash that was lose and stuffing evey thing up. so u might not of needed a new abs sensor. i cant rember wat type of car it was but year. when the earth goes off power from another dash light might b back feeding into the abs light and it will cum on and the tacho needle will go down because it will b on the same power feed. hope this helps

[caldy :)]

hi nemesis,

sorry no answer to your question but can you please run through the steps you took to replaceing the sensor, from what ive tried theyre a biatch to get out without breakin them... what did you do?

cheers mate.

[anthonym]

check you earths onto your battery we had a car at work that the tacho needle would go up and down and lights on dash would go on and off randomly and it had a seperate earth wire for dash that was lose and stuffing evey thing up. so u might not of needed a new abs sensor. i cant rember wat type of car it was but year. when the earth goes off power from another dash light might b back feeding into the abs light and it will cum on and the tacho needle will go down because it will b on the same power feed. hope this helps

Um did you actually read my post?

[anthonym]

hi nemesis,

sorry no answer to your question but can you please run through the steps you took to replaceing the sensor, from what ive tried theyre a biatch to get out without breakin them... what did you do?

cheers mate.

Yep they can be a total arse to get out, I know of 2 methods:

1/. Burly mechanic with pipegrips.
2/. Copious quantities of WD40, and hard blows with a hammer using a screwdriver on the flange of the sensor as well as tapping the flange back and forth on the horizontal plane to loosen it. This will bend the flange but did not damage the sensor in my case, YMMV. I also had the hub out of the car which improved access and the SW20 hub has a small groove that exposes the bottom of the flange (presumably to enable whacking it with a hammer ).

[MartinNZ]

How many wires on the sensor and what are their functions? If its 3/4 wire its possible the sensor or wiring loom has an intermittant short circuit which could pull down one of the supply rails inside the ECU or put it into limp mode?

Cut it open and have a look?

Martin.

[anthonym]

How many wires on the sensor and what are their functions? If its 3/4 wire its possible the sensor or wiring loom has an intermittant short circuit which could pull down one of the supply rails inside the ECU or put it into limp mode?

Cut it open and have a look?

Martin.

The sensor is a 2 wire magnetic reluctor, like all Toyota ABS sensors I think. I don't think a short is likely given the construction.