Alfa Romeo Forums banner

1 - 20 of 21 Posts

·
Registered
Joined
·
274 Posts
Discussion Starter #1
Hi there,

So our rescue Milano Verde is coming along and responding appreciatively to our attention on the brakes. Making good progress there.

One major issue that remains is the Tach and Speedo do not work. They both do not ever return to zero. The speedo sits on 10 mph and doesn't move and the tach stays at around 500 rpms and does move up a but when revving the engine, but nowhere remotely close to actual revs. (see photo). The temp, oil and gas guages all appear to work normally or very close, so it is just the speedo/tach that seems inop.
@Caxny and I haven't done much to troubleshoot it yet, but we take off and clean the connections to the amplifier under the rear seat. Interestingly, the nuts were only hand tight and in flipping it over we found the letters APE in paint, so it looks like this item was replaced at some point.

What do we think - does it seem the guage cluster might be the culprit? We are planning to start with an R&R of that, cleaning connections, grounds, etc. and hoping to fix/find problems, but are all ears to ideas.
 

Attachments

·
Premium Member
Joined
·
15,431 Posts
Well, first thing, that's where the speedo and tach needles sit when nothing is happening. It's normal. Don't worry about that part. Pretty much all Alfas have that feature, lol.

As for not reading higher values, haven't dug into that. Others may know the answer right off but it sure never hurts to clean and tighten all electrical connections and grounds.
 

·
Registered
Joined
·
897 Posts
On GTV6s, the normal issue is that the needles warp and brush against the dial face. It only takes a feather's touch to prevent them from rotating. I had heard that the Milano needles were made of a plastic less prone to warping. But as that could be the simplest solution, check that first. If that turns out to be the gremlin, then you can gently wiggle the needle away from the dial face a bit, so it makes zero contact. The needles don't need to be pushed all the way on to work.

If the needles are found to be the whammy, you can shorten the tips a little with finger nail clippers, and sand the back side with 400 sandpaper to get more miles out of them. If they are warped into a pretzel, you'll need to find fresh ones of course.

Good luck with your project,
Peter
 

·
Premium Member
Joined
·
15,431 Posts
Good point on the GTV6, but the needles of the Milano do rest where he says they are with his, as they do with our Milano, which I checked. They always have from new, not bent at all. That is usually not a problem, certainly isn't with ours, but who knows, they could be bent all right (maybe sunbent) but I kinda doubt it.
 

·
Premium Member
Joined
·
13,093 Posts
The APE box is the speedometer amplifier. They sometimes fail but are usually easy to repair. I can test it for you (no charge) and probably repair it (no charge) if you think that it is the problem. I have a thread about them that you should be able to find easily. The sender can be tested without removing it from the transmission (which is likely to produce an oil spill).
 

·
Registered
Joined
·
78 Posts
When driving (road or on jackstands) do the mileage and trip counters work? If so, the speedo sensor and amplifier are working. If not, check those.

As for the tachometer, there is an adjustment screw hidden inside the cluster for the tacho. However first I'd check that the wiring from the coil-to chassis plug-to cluster is all in order
 

·
Registered
Joined
·
897 Posts
Good point on the GTV6, but the needles of the Milano do rest where he says they are with his, as they do with our Milano, which I checked. They always have from new, not bent at all. That is usually not a problem, certainly isn't with ours, but who knows, they could be bent all right (maybe sunbent) but I kinda doubt it.
Yours is a good point too. As the Milano needles seem to hold up better than on GTV6s, I've swapped those onto my GTV6 speedos in the past. Since it was hinted that some of those bits may have been purchased used, and needles can be swapped out in both directions... I thought I'd throw that out as an easy option to check. He might have had a Milano with GTV6 needles.
 

·
Registered
Joined
·
274 Posts
Discussion Starter #8
When driving (road or on jackstands) do the mileage and trip counters work? If so, the speedo sensor and amplifier are working. If not, check those.

As for the tachometer, there is an adjustment screw hidden inside the cluster for the tacho. However first I'd check that the wiring from the coil-to chassis plug-to cluster is all in order
No they do not. Amplifier then? But why is the tach also broken?
 

·
Premium Member
Joined
·
15,431 Posts
My own feeling based on my experiences with all my Alfas through the years is that the gauges themselves rarely give up, have never experienced a failure even with car having ~180k miles, the usual problem being either the connections in the associated wiring, or the senders.
 

·
Registered
Joined
·
78 Posts

·
Registered
Joined
·
274 Posts
Discussion Starter #11
The APE box is the speedometer amplifier. They sometimes fail but are usually easy to repair. I can test it for you (no charge) and probably repair it (no charge) if you think that it is the problem. I have a thread about them that you should be able to find easily. The sender can be tested without removing it from the transmission (which is likely to produce an oil spill).
Thanks @alfaparticle - we might take you up on that. particularly the repair. :)

The tacho could be a strange coincidence. Could also be faulty wiring somewhere.

Check your speedometer sensor via this method
http://www.alfabb.com/bb/forums/milano-75-1985-1993/599578-testing-speedometer-senders.html

Connector can be easily accessed under the backseat near the amplifier.
If it checks out, you can then pretty much pinpoint it to the amplifier. They do have a tendency to break
Thanks - sounds easy enough. So if sender checks out, most likely its the amplifier, right?
 

·
Premium Member
Joined
·
13,093 Posts
Thanks - sounds easy enough. So if sender checks out, most likely its the amplifier, right?
It could be other things but the amplifier is the most likely. You need to use a signal generator to test the speedometer. A bad connection somewhere is also a possibility.
 

·
Registered
Joined
·
274 Posts
Discussion Starter #13
It could be other things but the amplifier is the most likely. You need to use a signal generator to test the speedometer. A bad connection somewhere is also a possibility.
Thanks AP. I think we will test the sender and also pop the cluster out and cleanup the connections.
 

·
Registered
Joined
·
4,273 Posts
Slow or dead tachometers in a Milano are very common. It requires cluster removal and repair - there is a potentiometer and capacitor (from memory) that need replacing. Many gauge shops can do this. My tachometer was slow to sweep in my car, so I removed it and sent to Palo Alto. They fixed it and calibrated it for a very reasonable price, something like $100, price may be higher now.

Non op speedometer? Wonder what the REAL mileage is on this car after all... :D

For what it's worth - someone clearly has been into that cluster. Inop Verde speedometers are also somewhat common.
 

·
Premium Member
Joined
·
13,093 Posts
If the signal wire from the amplifier to the speedometer is accidentally grounded when power is on it will blow the output transistor in the amplifier. I have tested a few amplifiers including several for Rob. They were all either working OK or the transistor was blown.
 

·
Registered
Joined
·
1,102 Posts
Were do we go from here?

Thought about a new thread, or tacking on to one of alfaparticle's threads on the subject, but why not keep all of the pain and suffering together?

Patient is an '88 Milano that suffered an instantaneous speedometer failure while being hustled on a freeway on-ramp. Needle went straight to to bottom (10mph?).

So far the transaxle sensor has checked (resistance) out OK.
The amplifier has checked out OK on a scope with a spare inductor and then with a TA sensor while spinning the rear wheel.
The last worry was the lack of battery voltage at the amplifier but that checked out OK once the dash was reconnected. This voltage is supplied through the speedometer/cluster.
Wiring was checked from amplifier to speedometer/cluster and seems OK.

Sooo . . . where to go from here?

Well, what is left? Just the speedometer itself. Is the speedometer serviceable?
Any other thoughts? Anyone have a spare?

Thanks.

peakay, is your speedometer working now?
 

·
Registered
Joined
·
4,273 Posts
Just a more general FYI, Speedometer itself is a pretty common failure on the Verde it seems. Palo Alto is the solution, he re calibrates the other gauges too for a very reasonable amount.

Sent from my SM-G935V using Tapatalk
 

·
Premium Member
Joined
·
13,093 Posts
The amplifier puts out a 12 volt square wave. I am in an airport now so no notes available but the instrument needs a certain voltage, maybe 6 or 7 volts. I know that the voltage needed by the tach depends upon rpm. It needs more voltage as speed increases. Insufficient signal results in the needle working correctly up to a certain rpm and then it drops to zero. It picks up again when rpm drops.
The last tach that I checked had a sticky needle. It read low on increasing rpm and high on falling rpm. Tapping the instrument would make it move to the correct reading. I have only messed with the electronic side of these things and I don't plan to get into the mechanical movement.
 

·
Registered
Joined
·
1,102 Posts
Hi AP,
Been all through your detailed posts. Excellent.

Is your last posted directed my way? To be clear, the problem is with the speedometer. The amplifier is showing very similar waveforms to what you have posted. The problem seems to be in the 'head'. Everything else seems to check out. Is there a frequency to voltage converter in the head unit? Or does the duty cycle along with frequency of the square wave change with speed, allowing some sort of analog conversion?

I'll probably dive into the gauge to see what's there is to see . . . but caution is the word without a replacement.

Happy trails.
 

·
Premium Member
Joined
·
13,093 Posts
I "think" that I know the answer but I will have to set things up on the bench to see for sure. Maybe in a day or two.
 
1 - 20 of 21 Posts
Top