Hi to all, first off all i want to apologize for my spelling, English is not my mutual language. I have a punto 2003 mk2b 1.2 8v without abs and i have a problem with my speedometer, stays at 0 when the car is moving and trip computer/ overall kilometres doesn't count.
Change new vss and the gear under of it
Test other ecu and bcm
Nothing of it fix the problem, all the other in the gauses working, i have permanently the red power steering light on and check engine.
At the garage while checking the Speedo goes to 200km/h so the needle work.
What other should I look?
Please help me ?

>>Change new vss and the gear under of it

The VSS probably produces a changing voltage. Have you checked that to ensure everything is working from that end of the system?

With the ECU wires disconnected it is fairly simple to trace the wires for the VSS back to the ECU and confirm the wires are good.

Alternatively the wires go to the body computer plugs but you can still trace them without much difficulty.

Best to do this testing work for the wires with say a 1000 ohm resistor to ensure you dont destroy sensitive electronics and use a voltmeter to ensure you got continuity of approximately 1000 ohms without passing any significant current along your test wire. So you test each length of wire by having the 1000 ohm resistor in the same loop of wires that passes thru the voltmeter set to ohms.

Thank you for replying, if i understand correct the wires from vss goes to engine ecu and then from ecu to body computer?
I have experience with multimeter.

Thank you in advance!

jimzak said:

Thank you for replying, if i understand correct the wires from vss goes to engine ecu and then from ecu to body computer?
I have experience with multimeter.

Thank you in advance!

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The ECU communicates to the body computer by a network where all messages pass down just a few wires. Those wires must already be working correctly or you would have much bigger problems.

Hopefully you just have a simple hardware problem involving the wiring from the VSS or to the body computer. Depending upon where those wires travel from the VSS

Thank you for replying, i will check the wiring tomorrow and I'll inform here if find something.

Good morning, i see the pin 10 of C connector to bcm it has no wire and as i see is for internal speedometer suply, what can i do?

jimzak said:

Good morning, i see the pin 10 of C connector to bcm it has no wire and as i see is for internal speedometer suply, what can i do?

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If the speedometer has previously worked in this car then that cannot be your problem. So I am not sure what you are telling me at the moment.

If second hand parts of your car have come from a car with ABS that could be your problem since the speed comes from the ABS unit and I suppose it is possible there are different body computers for those cars.

But what is your cars problem? Have you traced the VSS wires and then found the wires lead nowhere from the C plug?

If you can find the history of the car it will help.


Otherwise you should electrically trace/test the wires from the VSS and confirm the wires are in good condition before proceeding.

Is a second hand, or third, idk if worked before, actually bought with this problem and the mechanical before we buy it tell us the problem is the vss. We install new vss, new that gear under the vss, we try a new body computer and ecu by fiat serial number to be sure that fits to specific car, nothing happens... We have the power steering and engine check bulbs on, when we take off the battery for about five minutes the power steering light goes off and the steering wheel worked fine in normal and in city mode.

OK. Do you have the Multiecuscan cables and wires so you can get the power steering codes and other codes?

I am supposing the power steering module or the other modules can detect a problem with the VSS unit not being detected and produce a code. I am almost certain it is known a VSS problem causes the power steering light to come on.

However............you have not yet confirmed you have traced the VSS wiring to the unit which receives those wires. With a working VSS you will be able to monitor the VSS which is in the gearbox at the other end of the wire by putting some probes in the plug. You would not then have to change the VSS or gear and so forth. If the vss is a two wire plug which seems most likely to me then it will be just a coil of wire detecting a rotating piece of metal and will produce a changing voltage which can easily be detected at the other end of the wires. After the huge amount of work you have so far done you owe it to yourself to confirm you have that signal arriving at the plug before you do anything else.

I have the 16V with ABS so I cannot tell you which plug you need to look at to see that signal.

Thinking about it later, I have the unused plug for the gearbox sensor and those wires must? presumably be going to the ECU on my car and from there I am supposing the signals would go to the body computer via the network as a packet with the speed already encoded by the ECU which the body computer passes to the dashboard speedo module.


Multiecuscan cables and software can read those packets via the OBDII port.

Multiecuscan can directly read the engine ECU and report sensor information and work the various actuators like the injectors or the coils or whatever.

Thank you so much for response, the vss is check by car electrician and find it ok, it has 3 wires i measure the 2 at the sides and it gives me about 14v with working engine the middle one is for pulse, i trace the wires and in the engine part seems to be ok. I think the problem must be somewhere between the engine and the body computer, and i suppose the green/grey wire from pulse does the job and i think that because all the other things in gauses working. When the car electrician do a checking with his computer i see the needle to move from 0-200km/h so i suppose it's ok. Is a good idea to pull a line from the vss pulse wire directly to pin 17 at the body computer?
Thanks in advance again mate, i appreciate your trying to help!

Sadly i don't have multiecuscan to see the codes, but the mechanical and electrician tell me they see problem to vss from the program.

jimzak said:

Thank you so much for response, the vss is check by car electrician and find it ok, it has 3 wires i measure the 2 at the sides and it gives me about 14v with working engine the middle one is for pulse, i trace the wires and in the engine part seems to be ok. I think the problem must be somewhere between the engine and the body computer, and i suppose the green/grey wire from pulse does the job and i think that because all the other things in gauses working. When the car electrician do a checking with his computer i see the needle to move from 0-200km/h so i suppose it's ok. Is a good idea to pull a line from the vss pulse wire directly to pin 17 at the body computer?
Thanks in advance again mate, i appreciate your trying to help!

Sadly i don't have multiecuscan to see the codes, but the mechanical and electrician tell me they see problem to vss from the program.

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Since you are sure you have the correct equipment on the car it is not a good idea to connect wires that are not supposed to be connected.

This repair must have cost you a small fortune so far.

I would like to see the car jacked up and the correct signal appearing at the engine ECU when the engine is running to confirm the wiring is not shorted to something producing that 14V. Either way confirming a signal is appearing seems like a good idea.

Or is the test software saying their is a fault in the VSS without the engine running?

Fiat have their Examiner software which gives more information than an ordinary garage can give a customer.

We take the car to official fiat service and their software says the same, fault at vss sensor, we try a new one with no luck.

If someone with mk2b 1.2 8v without abs can upload a photo from body computer blue plug (c) wires i appreciate it.

jimzak said:

We take the car to official fiat service and their software says the same, fault at vss sensor, we try a new one with no luck.

If someone with mk2b 1.2 8v without abs can upload a photo from body computer blue plug (c) wires i appreciate it.

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If you can tell us what fault code fiat found it might help solve this problem. Perhaps.

jimzak said:

The fault code i think is P0500

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According to the post below P0500 is a circuit malfunction on those wires going to the speed sensor, or a fault in the VSS that looks like a circuit malfunction in those wires, or some fault in the ECU that looks like a circuit malfunction in those wires.

Since you have changed everything apart from the wires to the VSS the most likely fault is the wires.

https://www.fiatforum.com/punto-ii/422801-fault-code-p0500.html?p=4054145

If you go to fiat and ask them to print out what p0500 means you will know for sure what it means. If it means circuit malfunction on VSS, change the wires.

Update, i fix the problem, was a broken wire, that send the pulse from the plug near the engine fusebox to internal body computer,i send a new one from plug to bcm and now all seems to be ok, all works fine, Speedo , trip computer, steering etc... Thanks for help!