Technical Fiat Stilo Rain sensor

[borhan0089]

Hello friends,

I have a problem with my rain and light sensor in my Fiat Stilo 1.6 16V 2002.
It can not be learned as there is no signals from the sensor.
It was working very well, the car was parked for 3 months then I have this issue.
-I replaced it with another sensor but the same problem
-I did proxi alignment many times and disabling and enabling it.
-I did car configurations reset through MES
-I tried another Ecu (I have 2 ecus)
-Battery is new
-Fuse F49 is changed and fine.

Can anyone help me please, I don't what to do now and where they problem is
The sensor cable or connector has 3 pins.
I don't think that 2 sensors are defective.

I appreciate your help friends.

Thanks in advance.

 

[Ralf S.]

I didn't know Stilo's had a rain/light sensor option... Impressive!

But you're right.. it's unlikely to be a sensor fault, especially since the new one is similarly unresponsive.

You might need an auto-electrician to chase the connections to/from the fuse-box. Is the sensor getting power and is the signal it sends getting back to the ECU (or more likely the Body Control Module)...? etc.

Meanwhile you could take out the Body Control Module and give it a clean up. It lives under the dashboard, behind the little fuse box. You can disconnect about 4 or 5 plugs from the box and then unbolt it. Don't start hacking it just yet.. you may damage something.. but essentially it's a PCB inside a plastic case, with plugs bringing signals in and other plugs sending them out.

If you open the case you can give it a careful clean with a soft brush. I would NOT use contact cleaner since if it's too aggressive it can melt some of the plastic components on the board. Get a magnifying glass to check for burn marks, debris, dust or melted tracks etc. that might be causing the problem. Don't be tempted to poke the PCB though, since the car immobilisor is on there and if you break something, you might cause more serious problems.

Anyway, if you can't see anything obvious just clean up the pins for each plug and reconnect everything.. that might fix the issue.

My thought is that something on the BCM has become corroded and failed while the car was inactive, especially if it's been sitting somewhere cold and a bit damp. You may find that the sensor signal reaches the BCM but then the signal (to the wipers) doesn't emerge. I don't know the "in" and "out" pin numbers, I'm afraid.. but if you can find them out, that will be something that you could test and prove the problem is on the board.

Most ECU places can also check/fix BCMs, if it comes to it


Ralf S.

 

[borhan0089]

I didn't know Stilo's had a rain/light sensor option... Impressive!

But you're right.. it's unlikely to be a sensor fault, especially since the new one is similarly unresponsive.

You might need an auto-electrician to chase the connections to/from the fuse-box. Is the sensor getting power and is the signal it sends getting back to the ECU (or more likely the Body Control Module)...? etc.

Meanwhile you could take out the Body Control Module and give it a clean up. It lives under the dashboard, behind the little fuse box. You can disconnect about 4 or 5 plugs from the box and then unbolt it. Don't start hacking it just yet.. you may damage something.. but essentially it's a PCB inside a plastic case, with plugs bringing signals in and other plugs sending them out.

If you open the case you can give it a careful clean with a soft brush. I would NOT use contact cleaner since if it's too aggressive it can melt some of the plastic components on the board. Get a magnifying glass to check for burn marks, debris, dust or melted tracks etc. that might be causing the problem. Don't be tempted to poke the PCB though, since the car immobilisor is on there and if you break something, you might cause more serious problems.

Anyway, if you can't see anything obvious just clean up the pins for each plug and reconnect everything.. that might fix the issue.

My thought is that something on the BCM has become corroded and failed while the car was inactive, especially if it's been sitting somewhere cold and a bit damp. You may find that the sensor signal reaches the BCM but then the signal (to the wipers) doesn't emerge. I don't know the "in" and "out" pin numbers, I'm afraid.. but if you can find them out, that will be something that you could test and prove the problem is on the board.

Most ECU places can also check/fix BCMs, if it comes to it


Ralf S.

Thank you friend. I will check that

 

[borhan0089]

I didn't know Stilo's had a rain/light sensor option... Impressive!

But you're right.. it's unlikely to be a sensor fault, especially since the new one is similarly unresponsive.

You might need an auto-electrician to chase the connections to/from the fuse-box. Is the sensor getting power and is the signal it sends getting back to the ECU (or more likely the Body Control Module)...? etc.

Meanwhile you could take out the Body Control Module and give it a clean up. It lives under the dashboard, behind the little fuse box. You can disconnect about 4 or 5 plugs from the box and then unbolt it. Don't start hacking it just yet.. you may damage something.. but essentially it's a PCB inside a plastic case, with plugs bringing signals in and other plugs sending them out.

If you open the case you can give it a careful clean with a soft brush. I would NOT use contact cleaner since if it's too aggressive it can melt some of the plastic components on the board. Get a magnifying glass to check for burn marks, debris, dust or melted tracks etc. that might be causing the problem. Don't be tempted to poke the PCB though, since the car immobilisor is on there and if you break something, you might cause more serious problems.

Anyway, if you can't see anything obvious just clean up the pins for each plug and reconnect everything.. that might fix the issue.

My thought is that something on the BCM has become corroded and failed while the car was inactive, especially if it's been sitting somewhere cold and a bit damp. You may find that the sensor signal reaches the BCM but then the signal (to the wipers) doesn't emerge. I don't know the "in" and "out" pin numbers, I'm afraid.. but if you can find them out, that will be something that you could test and prove the problem is on the board.

Most ECU places can also check/fix BCMs, if it comes to it


Ralf S.

Do you have an idea how to replace the BCM? Is it easy like replacing ECU? I have Abritis and it was easy to virginize it.
Thanks in advance

 

[Ralf S.]

The BCM is a PCB, inside a plastic box under/behind the small fuse box, under the dash (right hand door side). It just unbolts from the car, once you have disconnected it.

I wouldn't do anything to it that's more than a visual inspection or clean up. The BCM contains various EPROM chips, a couple of which contain or process the immobilisor codes from the key to the ECU, to decide whether the car is going to start or not.

If the circuit that is receiving information from the rain sensor isn't passing it on, then that may be visible as physical damage to the PCB tracks but they are tiny and the PCB is covered in chips so you can't inspect the whole thing anyway. I would try to establish whether the sensor is communicating in/out at the sensor end first. If the trail takes you to the BCM then that's the time to find out where the "out" signal comes from (pin-wise) and that will prove whether the issue is in the BCM or not.

You can replace the BCM, if that's easier.. but it needs to be identical and you need to swap all the chips from your old one to the new one, so that the immobilisor still works.. but you need to prove it's the BCM first, then work out the best way to fix it later.



Ralf S.

 

[Maxcaddy]

It's an unfortunate fact that a 20 year old 1.6 Stilo is worthless, and certainly not worth any substantial investment to make right, hence time and money to repair marginal functionality (automatic sensors) is debatable re its value. That said, any miles you get out of it are a benefit, and if you can keep it running you're going to get cheap motoring.

So, I would suggest that other than than the joy/achievement of repairing it yourself, why not just stick to making sure it's legal and reliable. and treat fixing the sensors as a bonus. Always remembering that interfering with the electrical system can cause more trouble than success. I.e it won't be a positive result if you get the rain sensors working, but it won't start because the ignition is fubar