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[Webby the Bear]

Lad at college bought himself a 2004 Fiat Punto (1.2 I think  ).

Anyways, he said his speedo didn't work and that occasionally it flickered between 0 and 10mph but infrequently; most of the time it doesn't read anything!

So, he decided (without doing any testing  ) to buy a new speed sensor and replace it. He gets his new sensor and I can hear him from across the workshop moaning that he cant find the hole for it  . So he eventually fits it and his speedo is still not working.

He said that the only place he could fit the sensor (and which Autodata confirmed) was at the back of the gearbox but he had to take a blanking cap out of the hole  and there was a connector just hanging near it so he used this to plug in. 

SO.

We know this sensor wasn't hooked up yet he has had it flickering. So I'm thinking a couple of things....

1.) Is the speed actually taken from the ABS sensor? I don't think so but a possibility that it is and one of those is playing up?
2.) The speed is taken from the gear box speed sensor and perhaps the connector that's just flopping around is occasionally getting grounded by the engine when its moving causing sporadic jumps occasionally and the second hand sensor is junk?


I'm thinking his next steps are to see if there's a voltage coming out of the connector? if so then he can check the component for resistance? Or hook it up, back probe and look for voltage?

Any other ideas?

[Stemo]

Ideas for a 2004 punto? Plenty. All involve petrol and matches. 

[Webby the Bear]

 

Sensible answers please? 

[YZ250]

.................

SO.

We know this sensor wasn't hooked up yet he has had it flickering. So I'm thinking a couple of things....

1.) Is the speed actually taken from the ABS sensor? I don't think so but a possibility that it is and one of those is playing up?
.................

My daughter-in-law has a Grande Punto Sport (I think that's what it's called  ) and I seem to recall that if it's the model with ABS it won't have a Vehicle speed sensor as the readings are taken from the wheel sensors feeding the ABS ECU.
Don't quote me on that though as I'll have to check with my lad. 

[Webby the Bear]

.................

SO.

We know this sensor wasn't hooked up yet he has had it flickering. So I'm thinking a couple of things....

1.) Is the speed actually taken from the ABS sensor? I don't think so but a possibility that it is and one of those is playing up?
.................

My daughter-in-law has a Grande Punto Sport (I think that's what it's called  ) and I seem to recall that if it's the model with ABS it won't have a Vehicle speed sensor as the readings are taken from the wheel sensors feeding the ABS ECU.
Don't quote me on that though as I'll have to check with my lad. 

Thanks mate. If you wouldn't mind finding out I'd much appreciate it.

So if it is taken from the ABS sensor then we need to look for a duff sensor.... although I would have thought he'd have an ABS warning light on too?

 

[martin42]

It could be the speedo on the instrument panel has failed

[Webby the Bear]

It could be the speedo on the instrument panel has failed

An excellent point Martin.

How the break would you test the gauge?

[martin42]

Swap the dash with another that is know to be working.

[Webby the Bear]

Swap the dash with another that is know to be working.

That's going to be pretty difficult for him I think. is there any multimeter testing that can be done?

[henryd]

Swap the dash with another that is know to be working.

That's going to be pretty difficult for him I think. is there any multimeter testing that can be done?

My Snap on Solus Ultra will let you go into the instrument pack and carry out a function test on the dials and Lcd readout on many cars,don't know if it will do it on a fiat though

Edit  yes it will,just checked