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Discussion Starter #1
Okay so perhaps this is not the best first post, but here goes.

Caveat: I have searched and followed others methods to no avail.

I am the proud owner of my third alfa 75, a 1987 2.5 V6, which is in all round pretty good condition. However the only thing it requires to get a roadworthy is to fix the speedometer which is completely dead.

I began by assuming it would be a faulty connection - or probably the sensor. By removing the sensor from the transaxle, and cleaning it I found it to be in good condition, I sprayed the connections with automotive electrical cleaner and put it back in.

Quick test drive showed a dead speedo.

This time I was more thorough, following the wiring with a test light and multimeter I found that the circuit for the sensor is intact and carrying current as it should.

Following the wiring back to the dash I removed the instrument cluster and found everything to be in reasonable condition. I cleaned what could be cleaned and bolted it back together.

Still no speedo.

I have replaced all the fuses even though the test light found them to be carrying current.

Now I believe the problem is one of two things a) a broken speedometer or b) a faulty sensor.

Now I am at a loss as to what to do, new sensors are pricey and ebay is devoid of second hand parts.

Anything I haven't checked? Could the speedometer sensor not be in place properly (there is a few milimeter gap between the sensor and being hard up against the gearbox casing)?

In any case I am at a loss and any help would be fantastic.
 

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Did you check the speedometer pulse amplifier under the back seat? Often called the Jaeger box.
 

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Do you have the TSBs in the Cardisc? There are procedures for making a digital test light and then testing at the speedometer and at the amplifier. This will tell you if the speedo is actually bad or if it's the amp/sender components.
 

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Discussion Starter #4
Did you check the speedometer pulse amplifier under the back seat? Often called the Jaeger box.
I had a look for it and the weird thing is its just not there :confused:

I will follow all the wiring properly tomorrow to see if someone has relocated it for who knows what reason.
 

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I had a look for it and the weird thing is its just not there :confused:

I will follow all the wiring properly tomorrow to see if someone has relocated it for who knows what reason.
Wow Guy, that sounds confused and incorrect.;) I hope you find it. They aren't especially easy to acquire anymore.
 

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Tiny crack in pcb track

Usually the problem is that the connection to the printed circuit board (PCB) has failed after all these years.
Remove sensor from transaxle, open up sensor, resolder wire to PCB.
Relace sensor.

see here with more details here
 

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Discussion Starter #7
Well today I pulled out the rear seat and underlay, sound deadening and so on and found two disconnected plugs one blue and rectangular and the other white.

I am yet to find the amp box. That could just be because I have spent five minutes looking rather thandoing a proper job but alas between three jobs I have little time.

My current theory is that the interior retrimmer (the whole car has been re trimmed) had accidentally disconnected something.

Or perhaps the above by XAR75X is correct.

Either way there is hope yet.
 

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That does not look like a Milano sender. Maybe it is from a GTV6? The Milano sender is simply a coil. It is part of an oscillator circuit, the other componts of the oscillator are in the box, under the back seat.
 

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The sendor in the links is for a Manual 75 V6 transaxle.
Perhaps you all are talking about an automatic transaxle?

The amplifier / Jaeger box in my 1990 75 TS (Manual) is the grey box shown at the base of the pic below.

Sorry if I have confused things.
 

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you should update you local . so I will ask where are you? maybe some one is very close to you that can help you sort this out.. but with the location blank no one knows.
 

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That might be why it doesn't work.
 

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Discussion Starter #13
Ha you reckon?

Its just too neat from what I can tell here, I followed all the wiring and its perfect, all sealed in the original alfa sticky tape (tm). The earths look fine (can tell from the pic). Its just strange.

I have a electrician friend coming along some time soonish to have a look, hopefully something can get sorted out. If not I know of a alfa 90 I can raid for parts (thats assuming they are the same...) and a few other 75's.



Apologies for the giant image.
 

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...Apologies for the giant image.
If you have Microsoft Windows Picture Manager, (it comes with MS Office, I think) it can compress pictures for web pages.
 

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Discussion Starter #15
Well I have done some more playing around and this is a few photos of a sender identical to the sender I pulled out.

From what I gather this is the same as a gtv6 sender - which is odd. However, the build date on my 75 is 1986 which makes it one of the first ones I guess, my question is: Is there a parts crossover or has someone put the wrong sender in?

Either way I am going to slice that tube open and have a look.
 

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75 speedo sender unit

G'day 75Guy

I have the same year model as yours and it also doesn't have the box under the rear seat.
My speedo works, but registers about 10-15kph over the reality. That's another story.
I get the feeling that all the electronics are in the unit in the gearbox.
You'll probably be able to enlighten us.

Happy hunting

mutters
 

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Discussion Starter #19
Does anyone know the best way to cut the sender open? Before I reach for the hacksaw it would be good to know...
 

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From looking at your pic & my experience in electronics, I wouldnt use a hacksaw.

Put the unit in a vice - dont crush it, cut carefully around edges of the red plug where the wires go in.
Cut between white plastic case & red plug down to step edge of holder. Prise out plug if necessary.
Lift out plug as a disk with wires in the center, internals should lift out with wires.

Reseal with glue - silicone or similar.

Hats off to those who do their own repairs.
Goodluck.
 
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