I just continuity tested the (Brown) wire off the middle terminal of the tachometer (it is patched into a Red wire which terminates at the coil but is not connected to anything - in fact, when I first started working on the car it had a long plastic junction device on the end acting like a wire nut/cap)
Since my tach won't work if I connect a wire direct from that terminal to the coil my guess would be that the tach is shot!
Any rebuilders out there?
Has anyone rebuilt one on their own and can supply some "fix" direction?
'78 spider - Tachometer rebuilds
- MrBlimp
- Posts: 88
- Joined: Thu Jun 15, 2017 12:03 am
- Your car is a: 1978 Fiat 124 Spider
- Location: Chichester, NY
'78 spider - Tachometer rebuilds
69 Triumph Spitfire
70 MGB
78 Fiat 124 Spider
92 Mustang LX
00 Jeep Wrangler Sport 4.0L - Totaled
00 Ford Ranger XLT 3.0L
05 Hyundai Accent
70 MGB
78 Fiat 124 Spider
92 Mustang LX
00 Jeep Wrangler Sport 4.0L - Totaled
00 Ford Ranger XLT 3.0L
05 Hyundai Accent
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- Patron 2024
- Posts: 3015
- Joined: Fri Jan 27, 2006 11:45 pm
- Your car is a: 1981 Spider 2000
- Location: Wallingford,CT
Re: '78 spider - Tachometer rebuilds
Have you confirmed you have battery voltage on the + terminal on the back of the tack or the Yellow/black wire on the nylon connector?
Do you also have a ground on the white/black wire at the connector? The ground is shared for the internal dash lighting and the Tachometer section of the instrument.
If you connect a volt meter to the brown or brown/white wire at the tachometer connector while the engine is running do you have a voltage that is lower than battery voltage?? When the car is cranking but not running some meters will indicate a pulsing or changing voltage if the wire is properly connected to the coil - terminal.
One publication I find helpful to read is the Fiat publication "Spider 2000 Electrical Diagnostic Manual 1980-1981" Although it is not exactly for your car the principles of troubleshooting and the majority of wire diagrams are very close if not the same. You can find the manual on line and download it.
Do you also have a ground on the white/black wire at the connector? The ground is shared for the internal dash lighting and the Tachometer section of the instrument.
If you connect a volt meter to the brown or brown/white wire at the tachometer connector while the engine is running do you have a voltage that is lower than battery voltage?? When the car is cranking but not running some meters will indicate a pulsing or changing voltage if the wire is properly connected to the coil - terminal.
One publication I find helpful to read is the Fiat publication "Spider 2000 Electrical Diagnostic Manual 1980-1981" Although it is not exactly for your car the principles of troubleshooting and the majority of wire diagrams are very close if not the same. You can find the manual on line and download it.
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- Posts: 108
- Joined: Tue Oct 21, 2008 9:40 pm
- Your car is a: 1979 Pininfarina 2000
- Location: Cleveland Ohio USA
Re: '78 spider - Tachometer rebuilds
For what its worth, I documented the wires to the front panel from the connector kit on my 79 Pininfarina 2000.
I also had a problem with my instrumentation from a shorted IN4004 diode behind the gas gauge. It seems some of the wires to the front panel may not follow the same color convention as on the other side of the connector (the color which is shown on most of the electrical diagrams.)
Good luck
I also had a problem with my instrumentation from a shorted IN4004 diode behind the gas gauge. It seems some of the wires to the front panel may not follow the same color convention as on the other side of the connector (the color which is shown on most of the electrical diagrams.)
Good luck
- kilrwail
- Posts: 1100
- Joined: Wed Mar 04, 2009 6:49 am
- Your car is a: 1978 Fiat 124 Sport Spider
- Location: Perth, Ontario
Re: '78 spider - Tachometer rebuilds
To answer the OP's original question, Palo Alto Speedometer is a reputable instrument specialist, recommended in the Porsche world. Probably not cheap.
_____________________________________________________________
Peter Brownhill
1978 Fiat 124 Sport Spider - original owner
1977 Porsche 911S - track car
2022 Ram 4 x 4 - hauler
PCA National Instructor and Motorsport Safety Foundation Level 2 Instructor
Peter Brownhill
1978 Fiat 124 Sport Spider - original owner
1977 Porsche 911S - track car
2022 Ram 4 x 4 - hauler
PCA National Instructor and Motorsport Safety Foundation Level 2 Instructor
- RRoller123
- Patron 2020
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- Your car is a: 1980 FI SPIDER 2000
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Re: '78 spider - Tachometer rebuilds
Palo Alto Speedo is excellent! They repaired my clock and turned it around in less than a week at a very fair price.
'80 FI Spider 2000
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'74 and '79 X1/9 (past)
'75 BMW R75/6
2011 Chevy Malibu (daily driver)
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2003 Jaguar XKR
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- MrBlimp
- Posts: 88
- Joined: Thu Jun 15, 2017 12:03 am
- Your car is a: 1978 Fiat 124 Spider
- Location: Chichester, NY
Re: '78 spider - Tachometer rebuilds
Great diagram - Thanks.gchocevar wrote:For what its worth, I documented the wires to the front panel from the connector kit on my 79 Pininfarina 2000.
I also had a problem with my instrumentation from a shorted IN4004 diode behind the gas gauge. It seems some of the wires to the front panel may not follow the same color convention as on the other side of the connector (the color which is shown on most of the electrical diagrams.)
This seems to match my system. It would be great to know what the three wires are supposed to do and go to. That seems to be where my problem is. Especially since the brown wire doesn't currently connect to anything nor match the wire coming off the coil. I am going to try the other suggestion of connecting to the opposite side of the coil and see what happens.
69 Triumph Spitfire
70 MGB
78 Fiat 124 Spider
92 Mustang LX
00 Jeep Wrangler Sport 4.0L - Totaled
00 Ford Ranger XLT 3.0L
05 Hyundai Accent
70 MGB
78 Fiat 124 Spider
92 Mustang LX
00 Jeep Wrangler Sport 4.0L - Totaled
00 Ford Ranger XLT 3.0L
05 Hyundai Accent
- MrBlimp
- Posts: 88
- Joined: Thu Jun 15, 2017 12:03 am
- Your car is a: 1978 Fiat 124 Spider
- Location: Chichester, NY
Re: '78 spider - Tachometer rebuilds
YESspider2081 wrote:Have you confirmed you have battery voltage on the + terminal on the back of the tack or the Yellow/black wire on the nylon connector?
I believe so but will recheckspider2081 wrote: Do you also have a ground on the white/black wire at the connector? The ground is shared for the internal dash lighting and the Tachometer section of the instrument.
There is nothing on this wire as it wasn't connected to the coil - when I did connect it to the side of the coil as shown in wire diagrams I had a stead 12 volts.spider2081 wrote:If you connect a volt meter to the brown or brown/white wire at the tachometer connector while the engine is running do you have a voltage that is lower than battery voltage?? When the car is cranking but not running some meters will indicate a pulsing or changing voltage if the wire is properly connected to the coil - terminal.
Where can I get this book - I looked on line and can't find a copy anywhere.spider2081 wrote:One publication I find helpful to read is the Fiat publication "Spider 2000 Electrical Diagnostic Manual 1980-1981" Although it is not exactly for your car the principles of troubleshooting and the majority of wire diagrams are very close if not the same. You can find the manual on line and download it.
69 Triumph Spitfire
70 MGB
78 Fiat 124 Spider
92 Mustang LX
00 Jeep Wrangler Sport 4.0L - Totaled
00 Ford Ranger XLT 3.0L
05 Hyundai Accent
70 MGB
78 Fiat 124 Spider
92 Mustang LX
00 Jeep Wrangler Sport 4.0L - Totaled
00 Ford Ranger XLT 3.0L
05 Hyundai Accent
-
- Patron 2024
- Posts: 3015
- Joined: Fri Jan 27, 2006 11:45 pm
- Your car is a: 1981 Spider 2000
- Location: Wallingford,CT
Re: '78 spider - Tachometer rebuilds
Its on Mirafiori.com in the library. You have to be a registered member of the site and signed in to access their library.
Another location is www.njfiats.org Look under pull down menu "resources" then "Manuals & Guides" its a little over 1/2 way down this list.
The + side of a ignition coil connects to the ignition switch and is a constant voltage. The - side of a coil connects to the points or the ignition control module which ever you have. The tachometer connects to the - side of the coil as that is the side switching between ground and open to create your spark and drive the tachometer.
Another location is www.njfiats.org Look under pull down menu "resources" then "Manuals & Guides" its a little over 1/2 way down this list.
With the engine cranking and not running the - side of the coil should be a pulsing voltage. With the engine running the voltage should be less than the battery voltage. The higher the rpm the closer to battery voltage, the slower the rpm the lower the voltage and the more visible the pulsing should be. This is with the meter measuring DC volts. Not all meters work the same but this is worth trying.when I did connect it to the side of the coil as shown in wire diagrams I had a stead 12 volts.
The + side of a ignition coil connects to the ignition switch and is a constant voltage. The - side of a coil connects to the points or the ignition control module which ever you have. The tachometer connects to the - side of the coil as that is the side switching between ground and open to create your spark and drive the tachometer.
- MrBlimp
- Posts: 88
- Joined: Thu Jun 15, 2017 12:03 am
- Your car is a: 1978 Fiat 124 Spider
- Location: Chichester, NY
Re: '78 spider - Tachometer rebuilds
Thanksspider2081 wrote:Its on Mirafiori.com in the library. You have to be a registered member of the site and signed in to access their library.
Another location is http://www.njfiats.org Look under pull down menu "resources" then "Manuals & Guides" its a little over 1/2 way down this list.
That's what I assumed only NADAspider2081 wrote:With the engine cranking and not running the - side of the coil should be a pulsing voltage. With the engine running the voltage should be less than the battery voltage. The higher the rpm the closer to battery voltage, the slower the rpm the lower the voltage and the more visible the pulsing should be. This is with the meter measuring DC volts. Not all meters work the same but this is worth trying.
I tried both sides of the coil same NADA (and registering a steady 12 volts all the time)spider2081 wrote:The + side of a ignition coil connects to the ignition switch and is a constant voltage. The - side of a coil connects to the points or the ignition control module which ever you have. The tachometer connects to the - side of the coil as that is the side switching between ground and open to create your spark and drive the tachometer.
69 Triumph Spitfire
70 MGB
78 Fiat 124 Spider
92 Mustang LX
00 Jeep Wrangler Sport 4.0L - Totaled
00 Ford Ranger XLT 3.0L
05 Hyundai Accent
70 MGB
78 Fiat 124 Spider
92 Mustang LX
00 Jeep Wrangler Sport 4.0L - Totaled
00 Ford Ranger XLT 3.0L
05 Hyundai Accent
-
- Patron 2024
- Posts: 3015
- Joined: Fri Jan 27, 2006 11:45 pm
- Your car is a: 1981 Spider 2000
- Location: Wallingford,CT
Re: '78 spider - Tachometer rebuilds
This is strange. The - side of the coil needs to be connected to ground ( which it is when the points are closed) and then open when the points open this is when the coil produces the spark. So looking at the distributor cam one can see the points are closed for mor time than they are open. This means the ground is present more time than not. This should cause the voltmeter needle or digits to pulse when the engine is cranking and not running. If you have a constant voltage on both sides of the coil I don't see how you are getting a spark to run the engine.I tried both sides of the coil same NADA (and registering a steady 12 volts all the time)