ABS pump or sensors?

[FireFury]

2003 facelift MR2, the ABS light is on and the speedo has stopped working.  I've read the ABS error codes and it says 3 of the wheel speed sensors are dead (front-right and both rear).  If I reset the ABS errors the speedo starts working again, but only for a mile or so and then its dead again.

I've put a multimeter across all of the sensors and they each read about the same resistance (about 1 K ohm)... So I'm thinking this is most likely a dead ABS ECU (which is integrated into the ABS pump on facelift cars) rather than the sensors.  Does that sound the most likely culpret?  (I don't particularly want to replace all the sensors only to find that they were fine and I need to replace the pump too)

Changing the ABS pump doesn't look too hard - just disconnect all the pipes, swap it out, reconnect and bleed?

Thanks.

[jonbill]

changing one of the failed sensors might confirm.

[Gaz mr-s]

If the abs light & the failing speedo occurred at the same time, prior to that do you know if your abs system worked?  If you think the car was ok beforehand, 3 sensors can't have gone at the same time....?

[FireFury]

If the abs light & the failing speedo occurred at the same time, prior to that do you know if your abs system worked?  If you think the car was ok beforehand, 3 sensors can't have gone at the same time....?

The ABS light had come on but the speedo worked at first and the local garage said it was saying 3 failed sensors and their assumption was that the ABS ECU had probably died since 3 dead sensors seemed unlikely.  The speedo failed a bit later, which is when I read out the code myself (I was expecting it to say the final sensor had died, but it was actually still saying 3 failed).

Several of the wheel bearings have failed over the past few years and the garage had to replace ABS sensors when they did the work, but the ABS light didn't come on immediately after that and I don't *think* the rear-right bearing was replaced.

Its a bit weird that the speedo works ok immediately after resetting the ABS, but then packs up again soon after without producing any additional error codes.

[Gaz mr-s]

Does sound strange....hopefully someone reads that has come across this.