Technical Fiat Panda 1.1 2005 multiple problems.

[Zwyczajny]

Good morning! I've been having big electrical problems with my car lately, all kinds of things are happening.
the last problem I noticed and probably the most serious one is what is in the film.
While adding gas, the fuel level drops and the handbrake indicator light flashes.
Which plug to see if it has good contact?
The ground conduit is cleaned on the frame and gearbox.
Please help. thank you

 

[portland_bill]

That looks like a voltage issue at the gauges. You've already sorted the main earth (ground) cable, might be worth checking the main feed cable from battery to starter and alternator. These tend to be better than the earth, as they should be copper not aluminium core, but worth checking. Difficult, as it is behind the engine, and do this with the battery disconnected of course.

More likely are the connections at the gauges. Removal of these is supposd to be fairly easy. Poor connections will cause current to try to move along all the circuits trying to find an earth path.

When increasing engine revs, can you also check the alternator output, to ensure that is steady. If the alternator output is not regulated properly, voltage spikes could cause issues.

Check the drain tubes under the windscreen, inside the engine bay. If the chamber under the wipers fills with rainwater, it can overflow into the car, sometimes over the body computer, so check that is dry. If wet, disconnect and use a hairdryer to dry it out.

 

[Zwyczajny]

I started by improving the connection to the wheel arch, the gearbox, and the controller housing. I replug the tachometer again, the alternator gives a voltage of 14V while the engine is running.
The cables in the pit area were re-insulated around in the autumn and it is dry.
The resistance of all the grounds in the motor's casing is 0.2 Ohm, so it's fine there.
Even the immobilizer light up when engine running, so maybe something with the body computer in the cabin next to the left leg?

 

[koalar]

doe you have a voltmeter or multimeter or another car you can swap the battery out of ?

I would start with quick check on the battery and alternator first. Here in the UK they are often in cheap shops for under a £5

Let the battery rest for a few hours after a run then connect a volt meter on DC volts leads on the battery positive and negative terminals It should read 12.5-12.65 volts.

Start the engine should be between 13.5-14.5 volts. Mine is 14.1V. If its low try wiggling the wires if it jumps up suspect a loose connection

turning on the main beam, rear heated windows and blowers on max, voltage should remain above 13 volts, rev the engine it shouldn't go above 15V

report back and I will start to go through the wiring diagrams.

 

[Zwyczajny]

I was try all Yours ideas before, i saw that when issue is active for mikisecond then in the same time i hear relays work in Body Computer when speedometer, warning light and fuel level blinks, even immobiliser light show ups.
So i replug all connections in Body conputer without success, and got idea..

I lift Engine computer plugs about 1mm on IAW-4AF and right now, my Panda bolid seems to be fine, but i must find permanent solution, not temporary.

 

[koalar]

I was try all Yours ideas before, i saw that when issue is active for mikisecond then in the same time i hear relays work in Body Computer when speedometer, warning light and fuel level blinks, even immobiliser light show ups.
So i replug all connections in Body conputer without success, and got idea..

I lift Engine computer plugs about 1mm on IAW-4AF and right now, my Panda bolid seems to be fine, but i must find permanent solution, not temporary.

the normal fix for the 1.1 computer plugs is to cable tie the down. Which normally fixes it for ever

its quite risky to unplug them. If the pins are corroded its very easy to snap them off

the usual fault with the ECU connector is cutting out over bumps and is different to yours. But cable ties is worth a go

 

[Zwyczajny]

Someone know how to disassembly that plug without destroing?

 

[Zwyczajny]

@koalar You mean tie plug around all of engine computer?

 

[Zwyczajny]

Unfortunately today morning are same issue. My dashboard, wheelsteering support, and lights blink like christmas tree

 

[Zwyczajny]

New situation.

 

[koalar]

@koalar You mean tie plug around all of engine computer?

sorry for the delay I posted this yesterday but it didn't take for some reason

 

[Zwyczajny]

I do, but nothing change. i dont have idea whats happening. i saw many similar problems, but people who asking about solution never wrote how fix this.

 

[koalar]

I do, but nothing change. i dont have idea whats happening. i saw many similar problems, but people who asking about solution never wrote how fix this.

I didn't think it would .work

probably just a coincidence the you moved the lead it went away.

the Fuel gauge is powered and read directly via the body computer. Then sends the data to the dash

I need to look at the wiring diagram.

 

[DaveMcT]

Wires in "pit are

I started by improving the connection to the wheel arch, the gearbox, and the controller housing. I replug the tachometer again, the alternator gives a voltage of 14V while the engine is running.
The cables in the pit area were re-insulated around in the autumn and it is dry.

Disturbing old wires is always risky. Did you check for chafing? Have any of the wires chafed and created spurious connections?

Is the body computer dry? is the wiring good down there?

Fuse and relay connections can go faulty. I had a fault that chopped power to the BCU. It resolved after every fuse and every relay had been pulled and electrically tested. I never discovered what was actually causing the fault best guess is a relay.

 

[Zwyczajny]

I took out the entire siemens body computer, checked the power plug for it and the transition between the negative computer cable and the body and the power steering motor body was around 0.3 Ohm everywhere, so very good. Nevertheless, the fault persisted.
Unfortunately, when I ran out of ideas and hope without getting improvement, I twisted everything and decided to go to an electrician to take care of this matter. On the way to it, the car had no symptoms anymore, and I think it has regained a lot of power. It reacts immediately to acceleration and poses no problems.
It's not good that I don't know where the problem is, but it's ok now. I don't know for how long.

 

[koalar]

The body computer node, via the CAN network, also sends:

• the signal coming from the speedometer sensor K084, for managing the speedometer;
• the signal coming from the fuel pump N040, for managing the fuel gauge;
• the signal coming from the switch I040, for displaying the 'handbrake on' warning light
• the signal coming from the sensor K025, for displaying the 'low brake fluid level' warning light

I would, the next time the fuel gauge is fluctuating take out the rear seats and see if the voltage supply to the sender unit is constant

 

[Zwyczajny]

I think that if it repeats again, I will look for the reason why the voltage on the body disappears for a milisecond, which results in the temporary disappearance of controls, fuel gauge, speedometer, lights, wipers, and even the immobilizer and probably all things that are controlled by the body computer.
It turns out that if the negatives are good then the fault will most likely be in the power supply.

I also got a tip to look at the contacts in the ignition switch insert and the combined switch. This seems to be a good idea, because the voltage goes from the ignition switch to the body power relay, right? Do you know which relay it is so that I can examine the voltage drops on the power supply of its coil?

 

[koalar]

I think that if it repeats again, I will look for the reason why the voltage on the body disappears for a milisecond, which results in the temporary disappearance of controls, fuel gauge, speedometer, lights, wipers, and even the immobilizer and probably all things that are controlled by the body computer.
It turns out that if the negatives are good then the fault will most likely be in the power supply.

I also got a tip to look at the contacts in the ignition switch insert and the combined switch. This seems to be a good idea, because the voltage goes from the ignition switch to the body power relay, right? Do you know which relay it is so that I can examine the voltage drops on the power supply of its coil?

looks like the body computer is direct battery power via F01


"body computer node M001 (pin 1 connector) by the line protected by fuse F01;"


from memory the body computer both sends the power to the fuel sender and senses the voltage drop

if the volts drops to the sender then the problem will be pre body computer If the volts on the sender are steady then the fault will be post body computer. Of cause both could be the body computer but unlikely in my opinion.

 

[DaveMcT]

Your problem sounds a lot like my 100HP failing to start after the 2020 lockdown. I never found the cause but suspect it was a fuse or relay connection. The latter is most likely.