Technical Opening the windows causes Fuel/speed gauges to reset and click

[spyshagg]

Just finished checking that earth spot. Its perfectly fine


But wires don't go to that earth directly. There's a plug with a bunch of wires going into it, and the top of that plug connects to the earth spot. It was impossible to unplug that plug, so I don't know if board computer earth is good or not.


My dad recommended asking you where can I take a different board computer earth reading ?
We checked all visible current cables, and all are positives

 

[Deckchair5]

The diagnostic socket pins 4 and 5 are directly connected to the BC earth and should go straight to earth point C15B with near zero resistance

There's a plug with a bunch of wires going into it, and the top of that plug connects to the earth spot. It was impossible to unplug that plug, so I don't know if board computer earth is good or not.
Don't try disconnecting it, just do a voltage drop test on it (See the Stilo Guides for how to do that) All the wires there go to the earth so back probe any one of them (Slide a small pin down the back of the wire) and then voltage check between there and the battery earth with the engine running. Should be zero volts of course, anything over 0.5v and there's a resistance there that shouldn't be.

If there's a resistance problem simply undo the securing bolt/nut and clean up the contact points with wire brush and electrical cleaner and try again

Here I'm doing exactly that on earth point C12. Just cleaning up the tag is all you need to do

If your multimeter leads are long enough then you could do a volt drop test between BC diag socket pin 4 or 5 to battery earth

 

[spyshagg]

My dad has readings for you


Engine off key turned to off

Pin 4 to C15 = ~1.5 ohm resistance
Pin 5 to C15 = ~1.45 ohm resistance
Chassis to C15 = 0 ohm resistance

Voltage drop test

Current to chassis = 12.48v
Current to Pin 4 and 5 = 12.43v



Engine off with Key turned to MAR and selespeed pump working (first time turning key to MAR)

Current to chassis = 12v
Current to pin 4 and 5 = 11.90v

Selespeed pump off

Current to chassis = 12.26v
Current to pin 4 and 5 = 12.22



There is resistance but not enough to cause trouble? Dashboard ecu keeps reading minus one volt than the rest. 11.30v

My dad did this to overcome the resistance. Lets see if it works during the week.

If not, I may have to start from scratch on the problem we are scratching our heads right now. Can the dashboard alone (not bodycomputer) be responsible for:

Symptom 1: simply turning key to MAR increases mileage by 1.5 miles (not always, but frequent)

Symptom 2: From startup mostly in the morning during the first 300 meters: Relay shutsdown; Fuel gauge goes down; speed gauge might go down but rare; miles are added to Odometer; CITY turns off.


Symptom 3: Connecting ELM 237 or OBDII with fiatecuscan exacerbates the problems. Just connecting to SELESPEED ECU and let it stay connected for a few minutes will result in Loose connection errors and a bunch of relays clicking without stop, gauges go down. Nightmare. But I don't drive with cables connected, not a problem.

 

[Deckchair5]

Ok now a couple of things aren't making senseYou're calling it current when you're measuring the voltage but that's ok, we can still see what you're doing. I've changed your text below

Engine off key turned to off

Pin 4 to C15 = ~1.5 ohm resistance
Pin 5 to C15 = ~1.45 ohm resistance
Chassis to C15 = 0 ohm resistance
all ok

Voltage drop test

Voltage to chassis = 12.48v
Voltage to Pin 4 and 5 = 12.43v
All ok


Engine off with Key turned to MAR and selespeed pump working (first time turning key to MAR)

Voltage to chassis = 12v
Voltage to pin 4 and 5 = 11.90v

Selespeed pump off
All of those are fine

Voltage to chassis = 12.26v
Voltage to pin 4 and 5 = 12.22v
All fine and shows the body computer is within 0.04v of chassis so there's nothing wrong with that

There is resistance but not enough to cause trouble? Exactly

Dashboard ecu keeps reading minus one volt than the rest. 11.30v
Now where are you getting that from? You've shown that the body computer is within 0.04v of the chassis so where is this 11.30v coming from? Fiat EcuScan?

"Symptom 1: simply turning key to MAR increases mileage by 1.5 miles (not always, but frequent)

Symptom 2: From startup mostly in the morning during the first 300 meters: Relay shutsdown; Fuel gauge goes down; speed gauge might go down but rare; miles are added to Odometer; CITY turns off.
This will be a voltage loss/ lost connection/ reduced voltage


Symptom 3: Connecting ELM 237 or OBDII with fiatecuscan exacerbates the problems. Just connecting to SELESPEED ECU and let it stay connected for a few minutes will result in Loose connection errors and a bunch of relays clicking without stop, gauges go down. Nightmare. But I don't drive with cables connected, not a problem".
You'd need to contact Yani and ask if FiatEcuScan does that.

What I would do is disconnect battery and then remove the dashboard gauges connectors at the rear of the dash gauges and clean the connector contacts with electrical contact cleaner (Nothing else) let them dry and replace. Reconnect battery

Then i'd monitor the voltage at the BC or the dash gauges whilst you're moving

 

[spyshagg]

Took the car yesterday to the shop to change all front bulbs.



Instead of removing the bumper they decided it would be easier to remove the battery and disconnect all cables. To my dismay of course. It was too late when I saw them doing it.



And today the symptoms were much worse. Gauges went down 4 times. 5 miles were added to the odometer from thin air. Maybe I found the source.

 

[spyshagg]

Inspired by yesterday events, I decided to clean D4 and every plug in the vicinity.
guys, please keep reading to the end. There is a surprise...





First I cleaned fusebox cables including D4


Here is D4 and every plug cleaned with electrical contact cleaner.

Here is the fusebox also clean

Then I moved to the Board computer plugs.


Before cleaning and on close inspection I noticed something. A brown stray cable???

So I dismounted the board computer and found this hack job !!
A bunch of brown cables grouped together with every end connected to almost every plug!

The bunch of brown cables go deep inside the car, beneath the steering column

I wondered if they were earths cables. But I don't think so. They connect to blue and black cables and some other colours too. Information cables I think.



Yet I decided to see if there were any brown cables in the engine compartment.

There were.


Connected to the battery are two brown cables, the same type and all. One for voltage and one for earth

And here is were they lead to. To the alarm????

which begs the question. Do I have an aftermarket alarm?

 

[Steve148]

Damn, that's a rats nest. Well-spotted!

 

[spyshagg]

thanks

I just dont know what they do!! what are they for? lol

I'm going to ask the LPG installer if this belongs to them. If not, i'll disconnect all brown cables and see what happens.

I think it has something to do with the alarm. The way to connect aftermarket alarms to the CAN network seems the same way as the pictures above.

 

[Deckchair5]

Looks like a really poor alarm installation
With all that lot no wonder your body computer voltage was struggling to keep up

When you remove the mess, inspect very carefully the cable attachments points on the original wiring for damage or shorts as it looks like it's just held together with insulating tape