Coach,
The speedometer is an electro-mechanical device. While the sendor and amplifier are prone to fail, may I suggest you lubricate the speedometer head as well? There is a product on the market that is an electronic parts cleaner/ oxidation protector and lubricator, Boeshield T-9 is the brand name. Remove the speedometer drive unit from the gauge housing and give it a liberal bath. I think you will find much smoother speedometer response.
Good luck!
hi all, thanks for the replies.
i spent half a saturday finding out what went wrong, and found out that the speedometer is somehow not supplying the 12v to the amplifier/sender. i think it has shorted somehow. the signal and ground connectivity all round seems ok though.
what i did, i tapped another 12v supply from a connector somewhere in the glovebox, and supplied that to the amplifier instead. did that, took the car out for a spin and it was like 15 minutes of driving before the speedo starts to work again!
however, the intermittent behaviour is still there...the first round of driving, the speedo couldn't get past 80kph...it will just start jumping around, and stabilized again if i let go of the gas pedal.
this morning, it was better...managed to reach 160kph without much problem. i guess i've mentioned it in this forum before where if the car has been left under the sun for a while, the speedo will not work...somehow heat related.
maybe i'll try brian's recommendation in lubricating the speedo mechanism and see if it helps.
as for the SGI-5 device, i think long term wise it would be a good alternative, but living in Malaysia, the shipping cost is almost as much as the price of the unit! heheh!
i spent half a saturday finding out what went wrong, and found out that the speedometer is somehow not supplying the 12v to the amplifier/sender. i think it has shorted somehow. the signal and ground connectivity all round seems ok though.
what i did, i tapped another 12v supply from a connector somewhere in the glovebox, and supplied that to the amplifier instead. did that, took the car out for a spin and it was like 15 minutes of driving before the speedo starts to work again!
however, the intermittent behaviour is still there...the first round of driving, the speedo couldn't get past 80kph...it will just start jumping around, and stabilized again if i let go of the gas pedal.
this morning, it was better...managed to reach 160kph without much problem. i guess i've mentioned it in this forum before where if the car has been left under the sun for a while, the speedo will not work...somehow heat related.
maybe i'll try brian's recommendation in lubricating the speedo mechanism and see if it helps.
as for the SGI-5 device, i think long term wise it would be a good alternative, but living in Malaysia, the shipping cost is almost as much as the price of the unit! heheh!
mcandiago,
Great thread! I just thought that I would drop one alternative to the Dakota unit that I had been thinking about before I was aware of the Dakota: MegaSquirt.
A person would have to program it themselves, of course, but a person who uses megasquirt already might be up to the task. Some megasquirter running a ford trans in a Jeep is most likely doing this already. Other components such as amplifiers might be needed as well, I suppose.
I am not saying this is a better option, but it is an idea. I dont even have MS so I really dont know. Just thought I would pass on this idea and see if anybody knows anything.
James
Great thread! I just thought that I would drop one alternative to the Dakota unit that I had been thinking about before I was aware of the Dakota: MegaSquirt.
A person would have to program it themselves, of course, but a person who uses megasquirt already might be up to the task. Some megasquirter running a ford trans in a Jeep is most likely doing this already. Other components such as amplifiers might be needed as well, I suppose.
I am not saying this is a better option, but it is an idea. I dont even have MS so I really dont know. Just thought I would pass on this idea and see if anybody knows anything.
James
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Que Boludo
- Gold
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- Location: Australia Sydney
Dennis,is the picture of the yellow gtv your car??This is beautifull in yellow-If it is,please mail me the pic..
Sorry to interrupt the thread guys.....
Sorry to interrupt the thread guys.....
French cars are shit and shit expensive to service and bloody awful and unreliable and expensive and friends don't let friends drive french cars and you wait years for parts.
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Que Boludo
- Gold
- Posts: 83
- Joined: Sun Nov 28, 2004 9:02 pm
- Location: Australia Sydney
hi all...have been away for quite some time...mcandiago wrote:Thanks zambon,
Coach, I would recommend either taking the speedometer itself to have tested or trying an alternate unit that you know works. By the process of elimination you can converge on the true problem.
Cheers,
Marco
marco, this is what i did after that:
1) replaced the speedometer itself with another unit. tested, and the same intermittent behaviour results.
2) replaced the amplifier itself with another unit. tested, couldn't even make the speedo work! hahahah!
3) speedo sender. my mechanic has tested with 3 news one before, same problem.
but the worrying thing is that when the spare units in (1) and (2) were put into an alfetta (which did a conversion to 75 2.0TS), it worked fine!
i'm beginning to suspect it could be grounding problem. would appreciate it if pointers could be given as to which ground point the speedo units are connected to.
if you leave the car even in the shade for a few days, speedo would *not* work until 10-15mins, and that also with a "top" speed which the speedo will work till. this "top speed" will increase the longer u drive it, until it gets too long, then it starts to work intermittently again.
the mystery of the speedo problem in my 75 continues.
as aside, my alfa romeo control unit decided to have the brake and lighting warning lights keep blinking now. suspect it's due to ground problems again...any tips on which ground to check as well?
many thanks.
Coach,
O.K
It looks like your speedometer and amplifier are fine since this has been verified to work in a different car.
Your mechanic has tested 3 speedometer sensors same result.
I can only conclude something has gone wrong with the wiring and an intermittent ground is the most likely cause. I am not familiar with your speedometer so I don't know where the ground point is. Perhaps some else can answer this question.
This is how I would trouble shoot.
1. Verify that you have a 12V supply to your amplifier
2. Connect a ground jumper lead from the chasis (make sure it is a good solid chasis grounding point) to the speedometer ground and to the amplfier ground and to speedometer sensor ground. This way you can be sure to eliminate any grounding issues
3. If you have a three wire sensor check that you have a 12V supply for the supply lead. For the two wire sensor you SHOULD read 12V from the signal lead, which is the actual input to the amplifier. I say should because of the nature of the two wire sensor open collector design.
4. Connect a jumper directly from the output of the amplifier to the signal input of the speedometer, or verify that you have less then 5 ohms resistance from the output of the amplifier signal wire to the speedometer.
5. Perform the same operation for the input to the amplifer comming from the signal of the speedometer sensor. Ideally use a seperate jumper wire if you can.
By doing this you will essentially eliminate the current speedometer wiring and have replaced it with a known quantity. If everything works you can eliminate jumpers to discover which section of wiring is problematic.
Let me know how you go.
Marco
O.K
It looks like your speedometer and amplifier are fine since this has been verified to work in a different car.
Your mechanic has tested 3 speedometer sensors same result.
I can only conclude something has gone wrong with the wiring and an intermittent ground is the most likely cause. I am not familiar with your speedometer so I don't know where the ground point is. Perhaps some else can answer this question.
This is how I would trouble shoot.
1. Verify that you have a 12V supply to your amplifier
2. Connect a ground jumper lead from the chasis (make sure it is a good solid chasis grounding point) to the speedometer ground and to the amplfier ground and to speedometer sensor ground. This way you can be sure to eliminate any grounding issues
3. If you have a three wire sensor check that you have a 12V supply for the supply lead. For the two wire sensor you SHOULD read 12V from the signal lead, which is the actual input to the amplifier. I say should because of the nature of the two wire sensor open collector design.
4. Connect a jumper directly from the output of the amplifier to the signal input of the speedometer, or verify that you have less then 5 ohms resistance from the output of the amplifier signal wire to the speedometer.
5. Perform the same operation for the input to the amplifer comming from the signal of the speedometer sensor. Ideally use a seperate jumper wire if you can.
By doing this you will essentially eliminate the current speedometer wiring and have replaced it with a known quantity. If everything works you can eliminate jumpers to discover which section of wiring is problematic.
Let me know how you go.
Marco
Marco
1985 Alfa 90
1985 Alfa 90
hi marco,
thanks for the pointer. i will do that...i tried doing it during the weekend but realized my multimeter batteries were dead
have to go get new batteries for it.
also, i tested by pulling a wire directly from the ground of the amplifier to the battery negative terminal (temporarily for testing), but that doesn't seem to help. so next one i'll do the ground of the speedometer itself. oh yeah, the 75 TS speedo sensor/sender is the 3 wire type.
will let u know how it goes.
rgds,
coach
thanks for the pointer. i will do that...i tried doing it during the weekend but realized my multimeter batteries were dead
have to go get new batteries for it.
also, i tested by pulling a wire directly from the ground of the amplifier to the battery negative terminal (temporarily for testing), but that doesn't seem to help. so next one i'll do the ground of the speedometer itself. oh yeah, the 75 TS speedo sensor/sender is the 3 wire type.
will let u know how it goes.
rgds,
coach
Mcandiago, I have a 3-wire set in my gearbox and a 2-wire standard speedo on my GTV6 as Steve R said. I do have that amplifier from the 75/milano in a box waiting to be used, Can I plug all together and see my speedo working again then calibrate it? What should I do to make this work WITHOUT the dakota stuff?
Thanks beforehand
Thanks beforehand
'84 Red GTV6 3.0
Jose_76
To get your 3 wire set to work with your amplier I would do the following.
Connect a 12V supply from the ignition to the amplifier DC supply input.
All the wiring should be present under the rear seat of your car.
Jumper the 12V supply from the amplifier to the 12V input to the three wire sensor.
Connect the sensor Ground to the amplifier ground. Connect the The signal output from the sensor to the amplifier input.
Connect the output of the amplifer to the input of the speedometer (you need to find out what is the speedometer input)
Check that you have ground continuit between the speedometer ground, amplifier ground and speed sensor ground.
I believe this should work. However I guarantee your speedometer will not be calibrated correctly.
SteveR said there was a calibration pot inside the speedomter, but that you need to drill a hole to access. I don't know where that hole is you need to find out.
My suggestion, however, is to use the SGI-5 unit and follow the instructions previously posted by SteveR .
Marco
To get your 3 wire set to work with your amplier I would do the following.
Connect a 12V supply from the ignition to the amplifier DC supply input.
All the wiring should be present under the rear seat of your car.
Jumper the 12V supply from the amplifier to the 12V input to the three wire sensor.
Connect the sensor Ground to the amplifier ground. Connect the The signal output from the sensor to the amplifier input.
Connect the output of the amplifer to the input of the speedometer (you need to find out what is the speedometer input)
Check that you have ground continuit between the speedometer ground, amplifier ground and speed sensor ground.
I believe this should work. However I guarantee your speedometer will not be calibrated correctly.
SteveR said there was a calibration pot inside the speedomter, but that you need to drill a hole to access. I don't know where that hole is you need to find out.
My suggestion, however, is to use the SGI-5 unit and follow the instructions previously posted by SteveR .
Marco
Marco
1985 Alfa 90
1985 Alfa 90
Hi coach
If it works with Marco's instructions and the speedo is reading albeit incorrectly, then you might be able to correct it with the info in post 2 on this thread:
http://www.alfagtv6.com/bb/viewtopic.php?t=920
regards
Steve R
If it works with Marco's instructions and the speedo is reading albeit incorrectly, then you might be able to correct it with the info in post 2 on this thread:
http://www.alfagtv6.com/bb/viewtopic.php?t=920
regards
Steve R
83' GTV6, 3.0 24v supercharged