Replacing the sensor (especially a rear one) is the devil's own job. Depending on the age of your 164, the sensor will either be pushed into a hole in the rear upright casting itself or it will be pushed into a hole in a separate bolt-on casting on the side of the upright. Either way, because it is a stainless steel object being pushed into a cast iron hole, it corrodes in and generally refuses to come out. Its housing is very thin so any attempt at force will probably destroy it. It may be possible to remove the grub screw retaining it (although this is quite likely to shear) and then gently tap the tang backwards and forwards while applying plenty of release spray until it becomes loose but most efforts will be doomed.
On the cars where the sensor is fitted to a removable block, the complete block can be removed but only by withdrawing the two long bolts that hold the upright to the bottom of the damper. These are also generally corroded solid and the lower one often destroys the lower "wishbone" bush in the process of trying to withdraw it. If you are completely sure the sensor is faulty, the simplest solution is to smash it out and drill the central part out of the upright. Obviously, because of the difficulties in taking these things out, the chances of getting one from a scrapyard are small. At the time of writing, the cost of a genuine Alfa part was about £130 but places like "Alfashop" in Norwich sell them for nearer £100. Although all the sensors are electrically identical, the tangs that locate them are not in the same position so make sure you get the right one when ordering spares.
Finally, if the above tests show that there is nothing wrong with the fuse, relay or sensors, the problem must either lie with the control unit or the ABS pump itself or the wiring linking all the components together. From past experience, the "computer, ECU, Brain" or whatever you want to call it, is likely to be the last part to go wrong. It leads a pretty "cushy" existence inside the car where its warm and dry. It has no moving parts inside it either. The pump and valve block are also pretty durable but under the plastic cover on the pump assembly are a couple of relays which could possibly give trouble. The screw retaining the plastic cover over the relay housing generally corrodes up but it is possible to remove with a bit of effort!Top Previous Page
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by Ian Hopley.
© Ian Hopley / alfisti.co.uk 2002