Just thought i would post a few tips on the electronic speedo of the later spiders, as mine suddenly stopped working.
Basically if the speedo and the mileometer (tripmeter) stop working together it usually is a sign that the fault is not in the speedo itself (phew!)
If the speedo stops but the mileometer is still working, then the problem is in the speedometer guage itself. Alfa BB has many tips on repairing that, but it is not easy.
First thing to check is, is the blower fan working? no? then replace fuse 7, as fuse 7 runs the speedo and the blower fan, and the reverse lights on the S4 (possibly late S3 as well?).
If fuse is Ok, then next simple check is the black plastic plug connecting the wire coming from impulse generator up into wiring loom on bulkhead, which is situated (on the S4) just up by the brake servo unit. Check this, clean contacts, replace once satisfied.
Next possible cause is the speedometer cable.
Remove speedo cable from this pulse generator, and try turning and pulling the inner cable to see if it comes out in one piece (if it does check condition, oil it up and put it back, making sure it engages in the gearbox end, ie does not stick out too much) Mine came out Ok, but only 6 inches of the darned thing, so I knew that was the problem.
Replacing the speedo cable is a fidgity job unless you have the car up on a lift, but I just did it and it is Ok. I removed it, then fed a piece of coathanger wire through, and on the other end bent it around the new cable and fed it through that way. Worked fine. I tried taping the old to the new, but as the old cable was so oily, it just pulled off!
An easier way is just to replace the inner cable, but my outer cable was frayed and cracked in places.
If all the above checks out Ok, then the impulse generator itself is the most probable cause-this is the expensive part (if you can find one!)
Ebay.com has them secondhand once in a while, but only the version with the short wire, so you have to adapt
See link with one on Ebay for the later S3 models with electronic speedo, short wire version:
http://cgi.ebay.com/ebaymotors/Alfa-Romeo-Spider-Speedometer-Impulse-Generator-Cable-/230574983948
The original for the S4 with the long cable that has to reach up into the engine compartment are impossible to find.
The pulse generator is a simple hall effect pulse generator, meaning the speedo cable from the gearbox goes in one end and 3 wires come out the other through which a pulse is generated as the cable turns and that pulse feeds the speedometer.
I would suggest checking this with an electric drill and an old speedo cable. The one end fixed correctly to the pulse generator, and the gearbox end inner cable (which sticks out a fair bit) clamped into the drill. Operate the drill (preferably one with speed control and one that turns both ways, as I am not sure which way the gearbox turns the cable!) and get someone to see if the speedo (ignition on) is working, even slightly. I have not tried this, but i bet this method will work!
The speed impulse generator on later S3's (earlier S3's had mechanical speedos) should be near the clutch master cylinder under the bonnet, but that on the S4 is mounted underneath, near the exhaust on a chassis member, protected behind a small heat shield held on by two M8 bolts, quite easy to get at once underneath the car. With heatshield removed, there is one largish phillips head screw and the thing comes off - it has a small locating pin, you need to be aware of when putting it back, but that is obvious when you see it.
My speedo is working again, oh happy days
Note: rhd cars might have slightly different locations!
The illustration shows the short cable late S3 version
Basically if the speedo and the mileometer (tripmeter) stop working together it usually is a sign that the fault is not in the speedo itself (phew!)
If the speedo stops but the mileometer is still working, then the problem is in the speedometer guage itself. Alfa BB has many tips on repairing that, but it is not easy.
First thing to check is, is the blower fan working? no? then replace fuse 7, as fuse 7 runs the speedo and the blower fan, and the reverse lights on the S4 (possibly late S3 as well?).
If fuse is Ok, then next simple check is the black plastic plug connecting the wire coming from impulse generator up into wiring loom on bulkhead, which is situated (on the S4) just up by the brake servo unit. Check this, clean contacts, replace once satisfied.
Next possible cause is the speedometer cable.
Remove speedo cable from this pulse generator, and try turning and pulling the inner cable to see if it comes out in one piece (if it does check condition, oil it up and put it back, making sure it engages in the gearbox end, ie does not stick out too much) Mine came out Ok, but only 6 inches of the darned thing, so I knew that was the problem.
Replacing the speedo cable is a fidgity job unless you have the car up on a lift, but I just did it and it is Ok. I removed it, then fed a piece of coathanger wire through, and on the other end bent it around the new cable and fed it through that way. Worked fine. I tried taping the old to the new, but as the old cable was so oily, it just pulled off!
An easier way is just to replace the inner cable, but my outer cable was frayed and cracked in places.
If all the above checks out Ok, then the impulse generator itself is the most probable cause-this is the expensive part (if you can find one!)
Ebay.com has them secondhand once in a while, but only the version with the short wire, so you have to adapt
See link with one on Ebay for the later S3 models with electronic speedo, short wire version:
http://cgi.ebay.com/ebaymotors/Alfa-Romeo-Spider-Speedometer-Impulse-Generator-Cable-/230574983948
The original for the S4 with the long cable that has to reach up into the engine compartment are impossible to find.
The pulse generator is a simple hall effect pulse generator, meaning the speedo cable from the gearbox goes in one end and 3 wires come out the other through which a pulse is generated as the cable turns and that pulse feeds the speedometer.
I would suggest checking this with an electric drill and an old speedo cable. The one end fixed correctly to the pulse generator, and the gearbox end inner cable (which sticks out a fair bit) clamped into the drill. Operate the drill (preferably one with speed control and one that turns both ways, as I am not sure which way the gearbox turns the cable!) and get someone to see if the speedo (ignition on) is working, even slightly. I have not tried this, but i bet this method will work!
The speed impulse generator on later S3's (earlier S3's had mechanical speedos) should be near the clutch master cylinder under the bonnet, but that on the S4 is mounted underneath, near the exhaust on a chassis member, protected behind a small heat shield held on by two M8 bolts, quite easy to get at once underneath the car. With heatshield removed, there is one largish phillips head screw and the thing comes off - it has a small locating pin, you need to be aware of when putting it back, but that is obvious when you see it.
My speedo is working again, oh happy days
Note: rhd cars might have slightly different locations!
The illustration shows the short cable late S3 version