Technical unknown electrical connector

[stepheninlincolnshire]

hi all my first post so hopefully someone can advise me

i am trying to connect a reversing camera to my fiat panda 2007, I have threaded the wire from the head unit to the boot and made a bracket to fit the camera to, now all i have to do is to wire it up!
researching your forum it appears that i need to connect into the grey wire going to the rear light cluster?
however when poking the wire up into the boot i noticed this strange electrical connector hidden behind the rear bumper!

does anyone know what it may be used for?
I was thinking that it may be a factory fitted connector for a towing bar?
if so can i use this grey wire ?
will it be connected to the reversing light"!

 

[chris3234]

A multi metre on the light power feed will not destroy the body computer chip perhaps on a can bus wire on something like the airbag line maybe that are very sensitive to voltage and resistance

 

[koalar]

A multi metre on the light power feed will do destroy the body computer chip perhaps on a can bus wire on something like the airbag line maybe that are very sensitive to voltage and resistance

Correct, millions of cars are tested this way, every day

A multimeter has its dangers but in itself should never damage a BSI

The impedance is just too high

In the previous video I was conformable putting millions of times more load than a m/meter through the circuit, the BSI is fine, it's designed to handle it, if it wasn't I wouldn't have risk my BSI

Problems are usally down to operater error

Such as shorting two pins which might damage the BSI

Stuffing the probe tips into a connector will almost certainly spread the contacts and cause problems now or later down the line, I normally back probe with a T-Pin or just gently touch the contacts

Randomly poking things isn't a good idea

 

[jrkitching]

First disconnect battery and leave it for 2 hours minimum. Good idea is to remove the battery and leave it for a day. You do not want any of the canbus system to retain any charge.

I'd agree with this. Disconnecting the battery and giving the various capacitors time to self discharge is a sensible precaution prior to even attempting to open the hatch.

Then, with a key (central locking / electronic boot release will not work) open the boot and extract the connection similar to the photo above.

The 500 doesn't have a key to open the rear hatch; after removing the battery, you'll need to release it using the emergency release button from inside the rear compartment. Folding the rear seats down before you start makes this easier.

In what you identify about the 500 issue with wires to the rear hatch, Fiat seems to have the same mistake a lot of other car makers make - squashing too many wires through a hole and presuming the rubber grommet will protect them.

The problem isn't the size of the hole, nor is it chafing; it's fatigue failure of the cable due to work hardening as a result of repeated flexure. The grommet itself is usually intact; indeed this can fool you into thinking the wiring is sound, when it isn't. The individual wires don't usually short to ground through the chassis; they short to each other, with largely unpredictable results. In short (pun intended), enlarging the hole won't help.

The grommet is a sleeve grommet, and serves two functions; as well as protecting the cable, it also prevents water ingress into the rear hatch & main bodyshell. If you were to enlarge the hole, you wouldn't be able to replace this, and would end up with water seeping into the rear hatch. This will likely cause you even more problems.

The reason this happens is because there are basically two design faults: 1) the physical arrangement of the wiring means the cables are bent through a sharp angle every time the hatch is opened/closed, and 2) the cable used in incapable of withstanding the repeated flexure; both the insulation and the core fail due to work hardening embrittlement.

Since the first design fault can't be rectified, the only way of achieving a lasting fix is to splice in new sections of cable capable of withstanding the repeated flexure. Standard automotive cable isn't suitable, which is why many cars have failed this way multiple times.

There are various ways of connecting the spliced cables, with varying merits; this has been discussed several times here already. Suffice it to say that whatever method you use, it's essential that the actual spliced joints are made in a location that isn't subject to flexure, or the same thing will happen again.

 

[AndyRKett]

It seems to me that said person does not even understand the basics of Ohms law!

10,000,000 ohms is 10M ohm... and that will make a huge difference. Try put that load on your car and see how long the body computer will last!

<----- Ex Fluke UK electronics Engineer.....

 

[kmor panda]

Really? Altering the cross-sectional area by that much

There's no CANBUS in the rear light cluster, not in my or any other panda I have owned

I am not insane, or am I, probably

You don't know who am, what my experiance is,

After all It wasn't me that said the current increases on a dirty connector, in my world and ohms law a constant voltage and increasing resistance would have the opposite effect

I purposely made an error on one of my previous posts, to see if any electronic genius picked it up,

Believe what you wish.

1. Lights are controlled and sensed by the BODY COMPUTER despite what you wish to believe.
2. When one strips a cable, the outside of said cable is coated with impurities. As a result, when you twist them together, they may make a connection but will. due to the vibrations induced in a car and the hostile environment break electrical contact (although they are physically touching). As a result they will arc which causes the current to jump by a factor of 10... which I already stated and you dare to misquote me for some peverse sence of one upmanship. Are you still a child, or just behaving as one.
3. Current increases via arcing on a dirty connection which is the reason it heats up and melts connectors.

If you wish to purposely make errors on a post, as you state, then what can we believe out of you mouth?

@jrkitching
thank you for that added information, I do not have the 500 and it looked (from the picture) that the cable damage was from rubbing / compression and not from flexing. It still does not make sense to me that the cable is being overflexed unless it is tight earlier down the line which would cause cable stretching etc. The location of these cables is the top right of the boot where the cables, in the rubber, should twist roughly by 180 degrees. If they are tight in the grommet and/or tight at a point where they are being pulled while going via the grommet, there is not enough freedom for the cables to twist without breaking. If that is the issue, it might be a good idea to add french chalk inside the grommet or similar to increase the cable lubrication.
The filing I suggested is not to increase the size of the hole but rather to remove the sharp edges of the metal, a result of press cutting holes in metal. I also suggested glueing in the grommet as a way to keep the seal. The suggestion that you made of the cables getting hard over time should really not be an issue if one coats each cable (once electrical insulation is ensured) with cloth tape and french chalk / talc.

 

[AndyRKett]

I have not pulled anything apart and I have no knowledge of the specific circuits involved but we can conclude a few things from what I have seen.

1 the connected is outside the body of the car therefore exposed to water and debris behind the bumper. This is therefore not a plug for a towbar which which would have a plug inside the car, then additional wiring from the towbar relay going out of a gromit in the boot,

It matches with the diagram above suggesting this is a plug for parking sensors, it has the correct number of wires for parking sensors also. Unless I am very much mistaken, towbar electrics are 7 pin not 6?
The Parking sensor circuit is shown to be 6 pin.

Now this car does not have have parking sensors I assume or this plug would be in use, but a quick bit of research suggests that at least one of the parking sensor lines is a constant 12V (again I may be wrong) and this is likely to only activate when the car is put in reverse when the parking sensors are active otherwise they could be going off all the time if picking up interference or you have a trailer or something hanging out the back of the car.

So The OP has identified on this Plug a 12V signal that comes on when reverse is selected. If this is for the parking sensors then it is likely to be a seperate 12v from the body computer to tell the parking sensors reverse has been selected. So I would suggest that the OP is probably absolutely fine to use this wire for his reverse camera signal. Seemingly nothing has exploded yet.

If I were designing a logic system to use in a car I would be using ICs that are a little more tolerate of voltage levels. something that is tolerant of big spikes in voltage something that could cope with anything up to 20V being pushed through it. Not always possible so I would design something to protect any ICs that could not cope with big spikes such as having a well designed power supply for those circuits and separating them from anything likely to cause damage.

Bulb failure circuits are fairly simple, you know what the resistance range your bulb will operate in. you put another bulb in parallel to the bulb and then you measure the voltage across the parallel resistor. Using Kirchhoff's laws you know what voltage to expect across the parallel resistor so anything outside of that range is a blown bulb. There will be no direct link to delicate circuits in the body computer. the main risk is blowing the parallel resistor which is fairly straight forward to fault find and replace.

As stated I am an ex-Fluke engineer, I do know a thing or too about measuring voltages across a shunt.

 

[kmor panda]

I have not pulled anything apart and I have no knowledge of the specific circuits involved but we can conclude a few things from what I have seen.

1 the connected is outside the body of the car therefore exposed to water and debris behind the bumper. This is therefore not a plug for a towbar which which would have a plug inside the car, then additional wiring from the towbar relay going out of a gromit in the boot,

It matches with the diagram above suggesting this is a plug for parking sensors, it has the correct number of wires for parking sensors also. Unless I am very much mistaken, towbar electrics are 7 pin not 6?
The Parking sensor circuit is shown to be 6 pin.

Now this car does not have have parking sensors I assume or this plug would be in use, but a quick bit of research suggests that at least one of the parking sensor lines is a constant 12V (again I may be wrong) and this is likely to only activate when the car is put in reverse when the parking sensors are active otherwise they could be going off all the time if picking up interference or you have a trailer or something hanging out the back of the car.

So The OP has identified on this Plug a 12V signal that comes on when reverse is selected. If this is for the parking sensors then it is likely to be a seperate 12v from the body computer to tell the parking sensors reverse has been selected. So I would suggest that the OP is probably absolutely fine to use this wire for his reverse camera signal. Seemingly nothing has exploded yet.

If I were designing a logic system to use in a car I would be using ICs that are a little more tolerate of voltage levels. something that is tolerant of big spikes in voltage something that could cope with anything up to 20V being pushed through it. Not always possible so I would design something to protect any ICs that could not cope with big spikes such as having a well designed power supply for those circuits and separating them from anything likely to cause damage.

Bulb failure circuits are fairly simple, you know what the resistance range your bulb will operate in. you put another bulb in parallel to the bulb and then you measure the voltage across the parallel resistor. Using Kirchhoff's laws you know what voltage to expect across the parallel resistor so anything outside of that range is a blown bulb. There will be no direct link to delicate circuits in the body computer. the main risk is blowing the parallel resistor which is fairly straight forward to fault find and replace.

As stated I am an ex-Fluke engineer, I do know a thing or too about measuring voltages across a shunt.

As you correctly state, the body computer does use ICs and that the main issue would be blowing the parallel resistor in the voltage divider / sense circuit. The resistors are SMT block of 4/8/16 resistors. As a result, when one damages one in the block, it can effect 4/8/16 physically unrelated circuits. I have a body computer that one resistor in a block when short that damaged the controlling IC. I can't say for certain what caused it, but since a working body computer is not only expensive, but a lot of hassle to replace (hoping that it is programmed for your model etc.), it is better, and cheaper to be safe rather than be sorry if / when playing with this stuff.

You and I know the difference between multimeters and which ones can be used on TTL / car circuits and which can't and what circuits to avoid. As a result, is it advisable to tell another to play around with a cheap multimeter on a car?

Today, with the publication of electrical diagrams / service manuals etc of a car, it is safer to match cable colours rather than probe same with indeterminate impedence multimeters.

In relation to parking/reverse sensors, I have not come across a Fiat Panda with that design of rear bumper that has either mould marks and/or the plastic clips on the rear of the plastic bumper for parking / reverse sensors, so I doubt that that connection is for parking/reverse sensors. Secondly, that plug has a removable cap on it to stop water / dirt ingress. Normally, in a car model, the facilities are installed to allow a garage to add the optional extra like parking / reverse sensors without having to replace such a large item like the colour coded bumper. Secondly, in a mass production, making something unique is avoided. So logically, parking/reverse sensor connection does not seem valid.

 

[koalar]

Getting well out of hand it was all done and dusted by post 8 now up to post 28

Post 2 @the green vanper correctly identifies the connector parking sensor, same connector with the same colour wires

Post 1 @stepheninlincolnshire wants to sense the reversing light for the rear view camers

Post 8 @stepheninlincolnshire confirmed it's all working fine


Post 10 I posted the circuit diagram which clearly shows direct connection between the BSI and bulb no CANBUS and no extra connectors

Post 13 @kmor panda the wires aren't under specification, I have never seen a melted, burnt wire except where the cable been damaged, such as the horn or fan after an accident


Post 26 @AndyRKett the parking sensor is a dead duck unfortunately , The wires go under the seat and terminate where the missing parking module should be, thought I had already posted this, must have forgot to hit send

Post 25 @kmor panda
1 I said CANBUS is not involved, clearly I know the BSI controls the light as per my post 10 circuit diagram
2 a proper joined cable does not increase the amperage 10x, you have a towbar and bypass relay fitted, you already have a join in the reversing wire even if it was done by the previous owner, I take it your BSI isn't about to blow up
3 arcing does not increase the current causing the connector to melt, as per maxwell equations, more likely the hot plasma

This is not a fiat 500 and we are going way off topic but seeing as the panda does not suffer the same it would be very useful to compair the two hatches, probably needs a seperate thread

 

[kmor panda]

3 arcing does not increase the current causing the connector to melt, as per maxwell equations, more likely the hot plasma

Electric Arc - Wikipedia...

Devices which may cause arcing include switches, circuit breakers, relay contacts, fuses and poor cable terminations.
Arcing can also occur when a low resistance channel (foreign object, conductive dust, moisture...) forms between places with different voltage.
If a circuit has enough current and voltage to sustain an arc formed outside of a switching device, the arc can cause damage to equipment such as melting of conductors, destruction of insulation, and fire. An arc flash describes an explosive electrical event that presents a hazard to people and equipment.

An electric arc has a non-linear relationship between current and voltage. Once the arc is established (either by progression from a glow discharge or by momentarily touching the electrodes then separating them), increased current results in a lower voltage between the arc terminals.

Arc Flash Calculations

 

[AndyRKett]

You and I know the difference between multimeters and which ones can be used on TTL / car circuits and which can't and what circuits to avoid. As a result, is it advisable to tell another to play around with a cheap multimeter on a car?

I have used every manner of multimeter from £6K bench top units we made in Fluke to old fashioned analogue dial types, modern meters even the cheapest are fairly decent for a diy user. Something in the region of £10-20 from a reputable company.
And I have been crawling around in cars prodding wires with multimeters for >20 years now and been a member of car forums for a similar length of time…

I have never heard of or known anyone to cause damage to a module or a computer with a multimeter. Short of misusing the metre i can’t think of any situation that you would cause damage Probing some wires for the rear lights.

You talk about resistors in packages but this are much more robust than an actual logic IC.

In relation to parking/reverse sensors, I have not come across a Fiat Panda with that design of rear bumper that has either mould marks and/or the plastic clips on the rear of the plastic bumper for parking / reverse sensors, so I doubt that that connection is for parking/reverse sensors. Secondly, that plug has a removable cap on it to stop water / dirt ingress. Normally, in a car model, the facilities are installed to allow a garage to add the optional extra like parking / reverse sensors without having to replace such a large item like the colour coded bumper. Secondly, in a mass production, making something unique is avoided. So logically, parking/reverse sensor connection does not seem valid.

I have. The Eleganza cars from the early 2003 - 2009 period had optional parking sensors, a rarely specced option. Most manufaturers bumpers have a hole drilled in them and a clip for the sensor glued to the back of the bumper so do not need to be pre-moulded for such an addition. Source —— brother owns a body shop.

I agree with the comment above that if not fitted then the parking sensors should not have a computer and there should be no power on these wires, my Punto EVO had the same connector but no parking sensors connected (another high spec car) There is no cap over that connect it is open to the elements, If i had to guess i would say the OPs car did once have parking sensors and maybe the back bumper got damaged or the parking sensors stopped working so they removed the parking sensors and changed the bumper. In which case the parking sensor module would still be present and therefore there would be power on the connector.

In this case the worse case scenario if by sheer misfortune any damage was done to anything by poking about with a meter, it would only affect a parking sensor module that’s not actually in use, and do zero damage to the body computer.

 

[koalar]

Increasing the current lowers the voltage

We have a constant voltage so the current decrrases

MMA stick Welding when arcing everything is fine, when the electrode sticks the electrode glows red hot and the welder maxes out the current

It's the arc itself that melts the connector

What Causes Arc Flash? Electrical Arc Blast Explained

Arc flash vs arc blast. When an arc fault occurs, the result is a massive electrical explosion. The light and heat emitted by the explosion is known as the arc flash, and the pressure wave is known as the arc blast.

www.fluke.com

 

[kmor panda]

Increasing the current lowers the voltage

We have a constant voltage so the current decrrases

MMA stick Welding when arcing everything is fine, when the electrode sticks the electrode glows red hot and the welder maxes out the current

It's the arc itself that melts the connector

What Causes Arc Flash? Electrical Arc Blast Explained

Arc flash vs arc blast. When an arc fault occurs, the result is a massive electrical explosion. The light and heat emitted by the explosion is known as the arc flash, and the pressure wave is known as the arc blast.

www.fluke.com

Explain, using your logic, why car headlight bulbs blow when there is a poor connection on one or both of the battery connections as the arc would be created at the battery terminals, not the bulb the other end of the line?

One of the factors is said to be the a/c spike coming from an alternator, but that can't happen since it is rectified by the diodes / rectifiers on the rear of the alternator. Also, the alternator would not be creating voltage / current when the alternator inner coil is not energised by the battery during the time of partial / disconnection!

 

[koalar]

alternator would not be creating voltage / current when the alternator inner coil is not energised by the battery during the time of partial / disconnection!

This thread was finished post 8, this thread is about fitting a reversing camera

Half the time I don't know what we are talking about

But this is just plain wrong, once the ECU detects the Crank speed is over 700 rpm it instructs the BSI to stop suppling the current to the exciter coil and starts to monitor the voltage

I wouldn't recommend it but it's possible to remove the battery and drive the car once it been started, The battery acts as a big capacitor evening out spikes so in theory it's possible to fry the electronics, I certainly will not be trying this on my car,

 

[kmor panda]

This thread was finished post 8, this thread is about fitting a reversing camera

Half the time I don't know what we are talking about

But this is just plain wrong, once the ECU detects the Crank speed is over 700 rpm it instructs the BSI to stop suppling the current to the exciter coil and starts to monitor the voltage

I wouldn't recommend it but it's possible to remove the battery and drive the car once it been started, The battery acts as a big capacitor evening out spikes so in theory it's possible to fry the electronics, I certainly will not be trying this on my car,

Is this another tissue of lies.... or a purposely made errors on a post, as you did previously. Again, why should we believe what you post?

@AndyRKett ,
A - you don't need to prove what you post. There is enough information there to validate what you say. I am fully open to that FIat would have put a cable there for a reason, which you identified as reverse / parking sensors. However, that I doubt since I have been in at the wiring on My 169 to add electric wing mirrors and found that Fiat in its wisdom didn't even put any cables in the door / car for anyything else other than the central locking, electric windows and speakers. I had to run all the relevant cables from battery to door (via switches) for each mirror function including connecting to the rear demistor, via relay to power the heater in the window demistor. As we know, unique in mass production is expensive, yet Fiat chose to have unique wiring loom in each door depending on the electrical units fitted. That, by calculation is 140 different looms for a door. - so yes, Fiat could have multiple rear bumpers for each model.
B - In relation to finding wires on a car, I personally think that it is crazy to blindly probe with a meter unless you have some idea of the cables you are looking for - which most, if not all are available via service manuals etc. In relation to meters, Fluke are expensive since they comply to US Army reg.s etc. which is their market. As a result, there is enough designed protection within them to avoid / minimize damage to circuits. The normal cheap meters i.e. from car suppliers don't come with that luxury.

C - I suggested adding a £20-£30 trailer box for a few reasons -

1. It does not alter the load on original circuits to excede even the most sensitive run.
2. It seperates the load of a device (camera) so if it fails, no damage to reverse circuits will occur.
3. Options of secondary power socket can be added.
4. No huge extra work is required to fit same, since the OP is already running a cable the length of the car.
5. Toe bar is therefore mostly wired if the OP / another wishes to fit it at a later stage.
6. Every toe-bar box comes with its wiring digram (i.e. what cable to connect to what)
7. No real change is made to the OEM wiring of the car... and as such, no damage is possible to it.

 

[chris3234]

Explain, using your logic, why car headlight bulbs blow when there is a poor connection on one or both of the battery connections as the arc would be created at the battery terminals, not the bulb the other end of the line?

One of the factors is said to be the a/c spike coming from an alternator, but that can't happen since it is rectified by the diodes / rectifiers on the rear of the alternator. Also, the alternator would not be creating voltage / current when the alternator inner coil is not energised by the battery during the time of partial / disconnection!

What since when does. A poor battery connection blow headlight bulbs?

 

[koalar]

I have used every manner of multimeter from £6K bench top units we made in Fluke to old fashioned analogue dial types, modern meters even the cheapest are fairly decent for a diy user. Something in the region of £10-20 from a reputable company.
And I have been crawling around in cars prodding wires with multimeters for >20 years now and been a member of car forums for a similar length of time…

I have never heard of or known anyone to cause damage to a module or a computer with a multimeter. Short of misusing the metre i can’t think of any situation that you would cause damage Probing some wires for the rear lights.

Correct

I love my fluke 10 except no amps, really fast measuring resistors, if you have a board with a few 100 to check it's a pain waiting 5 or 10 seconds each one


But away from home I have bought a cheap meter and it does the job, I wouldn't trust the CAT rating but fine for for lower voltage automotive stuff

 

[kmor panda]

Correct

I love my fluke 10 except no amps, really fast measuring resistors, if you have a board with a few 100 to check it's a pain waiting 5 or 10 seconds each one


But away from home I have bought a cheap meter and it does the job, I wouldn't trust the CAT rating but fine for for lower voltage automotive stuff

Another idiotic mistake.

In a car, the voltages are around 12v, but it is DC and has currents of 160 amps.... while in domestic, voltage may be higher but the current is a lot less. It is a common mistake of people who have little information to presume the lower voltage is safer! @koalar is a typical example of a little knowledge may be dangerous / lethal.

 

[koalar]

Another idiotic mistake.

In a car, the voltages are around 12v, but it is DC and has currents of 160 amps.... while in domestic, voltage may be higher but the current is a lot less. It is a common mistake of people who have little information to presume the lower voltage is safer! @koalar is a typical example of a little knowledge may be dangerous / lethal.

Love the name calling

Let's look at the maths of the meter using ohms law

I = V / R = 14.1V / 10×106Ω = 0.000001A

It's not going to kill me
It's not going to blow the meter
It's not going to blow the BSI

You need enough volts (pressure) to push enough current (flow) though high resitance (body) which is why most chargers are 18V or under


A cheap made to a price meter will have tracks much closer together, I wouldn't trust my life on line voltage incase it jumps to adjacent tracks

But then again I could be wrong as I am insane idiot,

 

[chris3234]

Another idiotic mistake.

In a car, the voltages are around 12v, but it is DC and has currents of 160 amps.... while in domestic, voltage may be higher but the current is a lot less. It is a common mistake of people who have little information to presume the lower voltage is safer! @koalar is a typical example of a little knowledge may be dangerous / lethal.

DC is much much much safer then AC


And very little of a car is running anything like 160amp

 

[AndyRKett]

If I put any part of my body as a dead short across a 12v car battery I’m not going to get 160amps through my body that’s not how it works.

The reason we use 12v is because of its relative safety and the fact we sit the people in the middle of the body of the car which is used as ground.

Maybe if I put a meter in amps across the battery for a fraction of a second you’d get quite a lot of amps before the internal fuse turned to vapour.
But 12v is pretty safe and the electronics have to meet a standard that in the event of an accident and wires being shorted or severed, the various computers and modules are not going to blow up or create heat that will start a fire (as much as is practically possible.

I’d maybe recommend against probing airbag circuits or playing about with modern hybrids with 36 and 48V systems or higher in EVs but for the purposes of this thread no one died no one will die and the risks of any damage are extremely minimal