How to fix dead tachometer and speedomter? - Alfa Romeo Bulletin Board & Forums
 1Likes
Reply
 
LinkBack Thread Tools Display Modes
post #1 of 21 (permalink) Old 04-30-2018, 07:52 PM Thread Starter
Registered User
 
Join Date: Sep 2013
Location: California
Posts: 225
How to fix dead tachometer and speedomter?

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.
Attached Images
  
peakay is offline  
Sponsored Links
Advertisement
 
post #2 of 21 (permalink) Old 04-30-2018, 08:30 PM
Del
Senior Member
Gold Subscriber
 
Join Date: May 2005
Location: seattle
Posts: 15,106
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.

Del

Seattle

1989 Milano, Shankle Sport
1991 164S, stock
1994 164LS (~Q)
1972 Morgan 27

previously owned since 1964:

62 Morris MiniMinor 850, 67 Austin 1275 Cooper S (Downton 3/4 race), 64 Giulia Sprint GT (1st red one made), 72 Fiat 128 Sedan, 75 Alfetta Sedan, 78 Alfetta Sedan, 78 GTV, 81 GTV6, 86 GTV6

Last edited by Del; 04-30-2018 at 08:35 PM.
Del is offline  
post #3 of 21 (permalink) Old 05-01-2018, 08:19 AM
Registered User
 
Join Date: Feb 2015
Location: Burlington, VT USA
Posts: 856
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
planetmojo2 is offline  
Sponsored Links
Advertisement
 
post #4 of 21 (permalink) Old 05-01-2018, 09:17 AM
Del
Senior Member
Gold Subscriber
 
Join Date: May 2005
Location: seattle
Posts: 15,106
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.

Del

Seattle

1989 Milano, Shankle Sport
1991 164S, stock
1994 164LS (~Q)
1972 Morgan 27

previously owned since 1964:

62 Morris MiniMinor 850, 67 Austin 1275 Cooper S (Downton 3/4 race), 64 Giulia Sprint GT (1st red one made), 72 Fiat 128 Sedan, 75 Alfetta Sedan, 78 Alfetta Sedan, 78 GTV, 81 GTV6, 86 GTV6

Last edited by Del; 05-01-2018 at 09:22 AM.
Del is offline  
post #5 of 21 (permalink) Old 05-01-2018, 09:29 AM
Senior Member
Platinum Subscriber
 
alfaparticle's Avatar
 
Join Date: Oct 2004
Location: Columbia SC
Posts: 12,568
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).

Ed Prytherch
79 Spider
85 GTV6 3L
76 Suzuki GT500
2011 Jaguar XKR

A little government and a little luck are necessary in life, but only a fool trusts either of them. - P.J. O'Rourke
alfaparticle is offline  
post #6 of 21 (permalink) Old 05-01-2018, 09:32 AM
Registered User
 
75Tickspark's Avatar
 
Join Date: Aug 2017
Posts: 70
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

Restoring a 75 TS aka the tickspark.
75Tickspark is offline  
post #7 of 21 (permalink) Old 05-01-2018, 09:43 AM
Registered User
 
Join Date: Feb 2015
Location: Burlington, VT USA
Posts: 856
Quote:
Originally Posted by Del View Post
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.
planetmojo2 is offline  
post #8 of 21 (permalink) Old 05-01-2018, 10:14 AM Thread Starter
Registered User
 
Join Date: Sep 2013
Location: California
Posts: 225
Quote:
Originally Posted by 75Tickspark View Post
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?

1978 Alfetta Sport Sedan | 1985 GTV Lemons Racer
Instagram: Alfaddiction
peakay is offline  
post #9 of 21 (permalink) Old 05-01-2018, 10:36 AM
Del
Senior Member
Gold Subscriber
 
Join Date: May 2005
Location: seattle
Posts: 15,106
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.

Del

Seattle

1989 Milano, Shankle Sport
1991 164S, stock
1994 164LS (~Q)
1972 Morgan 27

previously owned since 1964:

62 Morris MiniMinor 850, 67 Austin 1275 Cooper S (Downton 3/4 race), 64 Giulia Sprint GT (1st red one made), 72 Fiat 128 Sedan, 75 Alfetta Sedan, 78 Alfetta Sedan, 78 GTV, 81 GTV6, 86 GTV6
Del is offline  
post #10 of 21 (permalink) Old 05-02-2018, 10:01 AM
Registered User
 
75Tickspark's Avatar
 
Join Date: Aug 2017
Posts: 70
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/mila...r-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

Restoring a 75 TS aka the tickspark.
75Tickspark is offline  
post #11 of 21 (permalink) Old 05-02-2018, 04:48 PM Thread Starter
Registered User
 
Join Date: Sep 2013
Location: California
Posts: 225
Quote:
Originally Posted by alfaparticle View Post
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.

Quote:
Originally Posted by 75Tickspark View Post
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/mila...r-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?
peakay is offline  
post #12 of 21 (permalink) Old 05-02-2018, 05:26 PM
Senior Member
Platinum Subscriber
 
alfaparticle's Avatar
 
Join Date: Oct 2004
Location: Columbia SC
Posts: 12,568
Quote:
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.

Ed Prytherch
79 Spider
85 GTV6 3L
76 Suzuki GT500
2011 Jaguar XKR

A little government and a little luck are necessary in life, but only a fool trusts either of them. - P.J. O'Rourke
alfaparticle is offline  
post #13 of 21 (permalink) Old 05-02-2018, 05:40 PM Thread Starter
Registered User
 
Join Date: Sep 2013
Location: California
Posts: 225
Quote:
Originally Posted by alfaparticle View Post
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.
peakay is offline  
post #14 of 21 (permalink) Old 05-03-2018, 07:58 AM
Registered User
 
racingswim2006's Avatar
 
Join Date: Apr 2006
Location: SE Michigan
Posts: 4,222
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...

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

Rob
Alfas first, then everything else.
racingswim2006 is offline  
post #15 of 21 (permalink) Old 05-03-2018, 09:28 AM
Senior Member
Platinum Subscriber
 
alfaparticle's Avatar
 
Join Date: Oct 2004
Location: Columbia SC
Posts: 12,568
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.

Ed Prytherch
79 Spider
85 GTV6 3L
76 Suzuki GT500
2011 Jaguar XKR

A little government and a little luck are necessary in life, but only a fool trusts either of them. - P.J. O'Rourke
alfaparticle is offline  
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Alfa Romeo Bulletin Board & Forums forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

 
For the best viewing experience please update your browser to Google Chrome