Strange ABS problem in ´96 850

[B234R]

Well, I´m getting a bit desperate with this.

For a few months my ´96 850 R ABS/TRACS lights came on now and then, until they kept on persistently.
So it goes like this:

1-Key in position II- lights on for two seconds, then off
2-Start engine, lights on briefly (one second?), then off
3-Drive the car, when I reach 20 kph the lights go on, ABS and TRACS don´t work.

VOL-FCR diagnostic says "ABS-443: Pump motor electrical or mechanical fault". If I clean the code and start to drive again, the code reapears.

Module (part number 9162675) has been changed for one from Matty Moo, so it´s OK. I feared it would be the ABS pump wires; the insulation was peeled off. I changed the pump for another from a ´97 V70 (part number 9157654B, it came with a module with the same part number than my car´s and Matty´s), with the wires in good condition, but the fault remains.

Off course, the V70 pump could be faulty, but it would be too coincidental. If I test the resistance in the pump plug with a multimeter, it gives about 6 ohms, which should be OK.

VADIS says that

"The control module also checks continuously for breaks in the circuit. The control module checks the pump motor by activating it the first time the car reaches 20 km/h (25 mph) if the brake light switch has been activated during the same period when the ignition is switched on, or under normal ABS/TRACS control. If the control module registers that the pump does not start, runs continuously, or there is a break in the circuit, DTC ABS-443 is posted.”

I suppose that it could be a good idea to test the pump starting it. If it works, it could be the large harness that goes to the module. How can I activate the pump?

If someone could think of anything, I would be very grateful.

[Matty Moo]

check your incoming power and your grounds. If the incoming voltage is low or you have an iffy ground it's going to do the same thing. You can put 12 volts straight to the pump to activate it.

[B234R]

Well, it has been a few weeks, but until yesterday I couldn´t take another look at it.
I was checking the fuses, and I realized that nº 9 (ABS Pump Motor) was blown. It seems it happened just before changing the pump, the bare wires touched and blew up the fuse. Then I replaced the pump and I didn´t care to check out the fuses.

A new fuse, and ABS/TRACS lights are off! it seems to me so strange to drive the car and seeing there isn´t any single light on...

Thanks to the forum, and specially to Matty Moo.