Alfa Romeo Forum banner

1 - 16 of 16 Posts

·
Registered
Joined
·
4,117 Posts
Discussion Starter · #1 · (Edited)
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
 

·
Registered
Joined
·
30,126 Posts
Really useful & timely thanks.

Mine dropped from 85 to 35 mph the other day yet it was cruising at the same speed:lol:

The car has been laid up for 8 weeks with the battery off but Leigh reconnected it today and when he took it out everything was back to normal.

The previous owner paid to have the speedo re-calibrated and the binnacle reconditioned so hoping it's just because of lack of use:confused:
 

·
Registered
Joined
·
1,841 Posts
Check if you can whether the calibration was done using the original potentiometer (variable resistor) on the speedo head unit or whether the reconditioning included swapping the old one pot. for a new one.

The old potentiometers were pretty poor to start with and with age get a bit unreliable so give intermittent faults (on/off) and the resistance can also change from day to day so the speedo reading changes. I replaced the one on mine with a new variable resistor from Maplins at a heady cost of about 90 pence! I calibrated it by checking using my TomTom satnav and altering the resistance until it matched the satnav. Its been totally accurate since then.
 

·
Registered
Joined
·
139 Posts
Probably a stupid idea, but is it possible to dismantle the pod? If so has anyone ever seen replacement dials for the speedo, gauges etc? I feel that the dials look dull in comparison to the S2.
 

·
Registered
Joined
·
1,841 Posts
Its pretty easy to dismantle the pod.

I have seen some alternative dials, white faced, on the Bulletin Board that SS4 references but I can't remember which thread. Probably somewhere in this very helpful but now very long thread. This thread also explains how to get the pod apart.

The white dials look more modern and sporty.
 

·
Registered
Joined
·
528 Posts
I too have a Spider S4 1990 the speedometer is fine but the odometer has just stopped working, any ideas please?
ditto. It moves on a few miles every now and again. The binnacle was replaced by a p.o. a couple of years back and the replacement was zeroed. I'm thinking that's probably the cause
 

·
Registered
Joined
·
4,117 Posts
Discussion Starter · #10 ·
I too have a Spider S4 1990 the speedometer is fine but the odometer has just stopped working, any ideas please?
Firstly a tip: the absolute worst thing you can ever do is to reset the tripmeter when the car is moving....you wouldn't drive up the motorway and then try select reverse gear.....think about it.....:)

just been speaking to a german alfa forum member who specialises in the S3/S4 monopod instruments here in Germany.....
the odometer is quite fragile he says, by design.....there are ultra thin wires soldered to the 'motor' which with vibration, break.
If you do not know what you are doing and try solder them back you can destroy the solder points and then you need a new instrument. If you are successful, the wires need to be placed carefully before putting it back (he is a TV technician and says you need experience to use exactly the right temperature and a solder iron with extreemly fine tip)

iow. your halfords soldering iron ain't no use;)

A much rarer occurance is the little cog breaks.

Alfa Romeo Bulletin Board & Forums - View Single Post - How to fix your slow reading speedometer or tachometer on 91-94 Spiders
 

·
Registered
Joined
·
202 Posts
Thanks all for these tips.

My 1991 LHD Spider Veloce's speedometer appeared to have failed (along with the odometer) and I normally use a He-Man HUD thing or my Tom Tom to keep me honest on speed.

Recently, however, I noticed that it started working again above 40 mph but only when the aircon was on. The only other change I had made to the car was to put the hardtop on it, but I had not connected the rear screen heater. (The hardtop was on in high summer because I was taking the car back to the UK for an MOT and respray before anybody asks:))

Very odd but I can only replicate this intermittently. I suspect a bad earth somewhere.

The car is an automatic if that makes any difference.

Peter
 

·
Registered
Joined
·
2 Posts
Thanks for the information to be honest I think that I tried to zero the odometer whilst moving, can this be repaired easily? Do you know of anyone that can do this please? I am in the UK.
 

·
Registered
Joined
·
4,117 Posts
Discussion Starter · #13 ·
Thanks all for these tips.

My 1991 LHD Spider Veloce's speedometer appeared to have failed (along with the odometer)
Very odd but I can only replicate this intermittently. I suspect a bad earth somewhere.

The car is an automatic if that makes any difference.

Peter
first check connections at fusebox behind fuse #7 (this controls speedo, reverse lights, heater fan and cigar lighter, so if any of those work, the fuse is OK)

as both speedo and odo have stopped it could be the speedometer pulse generator.
Anglospider (Nick) knows far more about the autos speedo set up. Maybe he'll chime in.

being an automatic, the speed generator is quite different to manual cars, and replacements are very hard to find, if at all (see photo of what it looks like: alfa PN 60575205 or Veglia Borletti 68.0529.0_G2 12V)

recently I came across this site which explains how to test the generator (sensor) on a ferrari...the type 2 (on the right) seems very similar to the S4 spider's, maybe the tests are the same for the alfa sender......??
Veglia Borletti Speedo Sensors 68 1005, 68 1041, 68 0517
 

Attachments

·
Registered
Joined
·
1,841 Posts
I don't think I know any more than you about these, Dom, apart from some hands on experience!

The problem is unlikely to be a bad earth as the pulse generator earths through its casing. If you compare it to a manual cars generator you will see that there are only two wires, vs. three for the manual car. One of the three in the manual car is an earth wire.

One of the two wires on the automatic car generator carries the signal (blue grey colour, from memory) to the speedo head, the other (pink, again from memory) feeds 12v to the generator. The wires can fray so its worth connecting up separate wires to see if that is the problem. You can get to the connectors if you can get under the car, the generator is screwed into the side of the gearbox.
 

·
Registered
Joined
·
202 Posts
I don't think I know any more than you about these, Dom, apart from some hands on experience!

The problem is unlikely to be a bad earth as the pulse generator earths through its casing. If you compare it to a manual cars generator you will see that there are only two wires, vs. three for the manual car. One of the three in the manual car is an earth wire.

One of the two wires on the automatic car generator carries the signal (blue grey colour, from memory) to the speedo head, the other (pink, again from memory) feeds 12v to the generator. The wires can fray so its worth connecting up separate wires to see if that is the problem. You can get to the connectors if you can get under the car, the generator is screwed into the side of the gearbox.
Thanks. I have a lift at my second home, so I can get under the car quite easily once I have the S4 back there. I shall do as you suggest.

Peter
 

·
Regional Support, For Lincolnshire - AOL
Joined
·
16,411 Posts
I don't know if the set up on the Spider is anything like it is on the Alfetta but here is how I solved my problem on that.

Step 1 of today was to check the wiring from Sensor to Head for continuity and shorts, all OK except for one bizarre thing which I will get to in a tic.

Step 2 was to check the ignition switched 12 Volt feed which joins in the game at connector S2, all OK.

Step 3. Looking at the Speedo Head I found that the 12 volt into the Head had been disconnected on the Head itself. Why ? Was it blowing fuses or was this a " Clocking " attempt ? I suspected the latter.

Step 4. Reconnected this and checked all fuses and services, all OK.

Step 5, the crafty bit !!!! Disconnected the plug from the Sensor and connected two pigtails to the plug that goes to the Speedo. One pigtail was connected to a an ordinary metalworkers file tang, the other pigtail is then scraped along the face of the file. ( Ignition has to be 'ON ' for this of course. ) Wow, the Speedo starts flicking about, result !

Full of hope as I thought a previous owner was trying to stop the miles from clocking up I went for a drive, sadly still no Speedo.

Step 6. Removed the Sensor from the Gearbox, easy job, undo one bolt and the unit pulls out. No oil is lost at this point. The way this unit works is a mag pulse generator driven by a square ended Speedo sort of drive. Across the two terminals you should be able to measure the coil resistance, mine showed to be so high I considered it to be open circuit. Then twist the drive cable with your fingers, you should feel a bit of " jerkiness " as the magnets interact with the coil, mine did.

Step 7. Can't vouch for this bit of the testing. Connected a drill to the drive to spin it and tried to measure the output with a DMM, got no readings at all either DC or AC Volts which is what I would expect if anything on this method. A 'scope would have been handy at this point but sadly I no longer have one.

Conclusion. The coil in the sender is open circuit, I need a new one, or at least one that works. It is made by Veglia and the markings on the case read :-
68 - 1027 - 2D
12v - 4 - P/G

Finally solved it In the end by replacing the two Transistors and the Zener Diode in mine ( BC 327 & 33 Volt Zener ) and that got it going, I suspect that it was one of the Transistors. If you are, or know someone who is, happy working on Printed Circuit Boards, then it’s a fairly simple job, the hardest part is Splitting the Unit itself, the rest is easy.

First thing though is to make sure that it is the Sender. Check the connections are clean and tight. Check that the 12 Volt supply from the car is present. To test the Sender disconnect the connections from it and attach flying leads to the wires that go to the car. Connect one of these firmly to the tang of a normal metal work file, switch on Ignition, scrape the other wire along the File, the Speedo should flick around at random. If this doesn’t happen remove the Speedo Head and check all connections and the 12 Volts there.

It could be that you have dry joints on the PCB, this is the next thing I would try, remove all the old solder, clean up very carefully and resolder.
 
1 - 16 of 16 Posts
Top