Seat Ibiza Electrical Problems - 2000

Hello fellow enthusiasts,

I'm having some serious problems with the electrical system in my car.

The vehicle is a Seat Ibiza manufactured in October 2000, with an 81kW TDI ASV engine, "Signo" trim level, featuring automatic climate control and the integrated radio system. (For those unfamiliar: the radio, multi-function display (MFA), and climate control are all integrated into a single large unit.)

Problem description: When the ignition is turned on, the radio/climate control display no longer illuminates. All the buttons on the radio/climate control unit are no longer lit up. The ventilation/heating controls are not functioning. The ventilation appears to be running in an emergency mode with a medium fan speed.
I also have a permanent positive voltage on the K-Line (diagnostic connector).

Previous diagnostic attempts:
The radio/display unit was removed and inspected for cold solder joints and poor connections.
Nothing was found. When reinstalling, it worked briefly again; everything functioned normally. However, after turning off the ignition, the radio/climate control unit stopped working again.
Repeatedly turning the ignition on and off can sometimes temporarily restore the radio/climate control unit to working order, but this is not a reliable solution.

If I remove fuses number 26 and number 29, the constant positive voltage on the K-line disappears. With VAG-COM, I can then also communicate with the engine control unit.

According to my Dutch owner's manual, fuse #26 controls the combination lighting, a panel display (?), the electrically adjustable exterior mirrors, and the dashboard lighting (?). It is also true that this fuse completely cuts off power to the radio/climate control unit. The display of the radio/climate control unit is then completely turned off.

Fuse #29 is only responsible for the radio. Even if you remove it, you can still see the time on the display of the integrated radio/climate control unit.

Here's a link to an image showing the fuse layout.
http://tumblefish.gmxhome.de/Sicherungen.jpg

I haven't messed with the comfort electronics; the car is standard except for a boost pressure increase achieved through a voltage divider and a tuning box, which have been installed for years.

My suspicion is that I have a short circuit somewhere, possibly caused by rainwater entering near the door (affecting the electric exterior mirrors), because the constant positive voltage on the K-line disappears when fuse #26 is removed. The air conditioning/radio system is also connected to this fuse. I'm currently in Scotland, and it's raining quite a bit here. Additionally, the error described here occurred immediately after a heavy rain. The doors are the only place where water could have entered; everything inside is dry.

So... does anyone have any ideas?
Can someone tell me the easiest way to disconnect the entire electrical connection to the door? Is there a plug somewhere that I can simply disconnect?

Thank you very much.
Georg.

Moisture can also enter the engine compartment from below and then travel from the engine compartment into the interior of the car. Check the negative/ground cables for oxidation. This means disconnecting them from the terminals, cleaning them, and then reattaching them, and possibly lubricating them.
Regards,
Olli.

Feedback:


Okay, the problem has now been resolved.

The radio/ventilation unit is slightly damaged by a strange layer on the underside of the circuit board. It looks like soot deposits, but it's definitely a superficial oxidation. Carefully cleaning the circuit board with ethanol has almost restored it to working order: There is still a constant transmission of +0.5V to the K-line.

I'm now only connecting the entire box to the ignition positive and ground terminals (as well as the speakers and stepper motors for the ventilation/blower). This way, everything works as before, but I unfortunately have to forgo the diagnostic capabilities of my radio and climate control system.

By the way, this part costs approximately 360 euros from Seat.


Best regards,
Georg.

Oh, while I'm at it:

In the Ibiza, you can disconnect the entire wiring harness that goes to the driver's door by disconnecting three rectangular connectors (white, brown, and green) located directly under the fuse box in the driver's footwell.

The passenger door is similar, but you first need to unscrew a panel in the passenger footwell. Then you'll see three connectors.


Best regards,
Georg.

Hi Georg,

I just saw your thread now... I've been very busy the last few days.

I could have told you about the connection to the door .

The clock seems to be running independently, because when the entire unit was initially broken, the clock was the only thing that still worked. Fortunately, the replacement of the module was covered under warranty.

Have you figured out where this strange coating came from? It's definitely not normal, and it doesn't belong there.

Best regards,

Jan.

Place the entire oxidized circuit board in ethanol. This can also help with water-damaged phones. However, the plastic should not come into contact with the ethanol for too long, as it can dissolve.

Okay, disassemble the device, put all the electronic components in ethanol, and wait 24 hours. Then, rinse with ethanol and let it dry.

Edit:

The condensation may have formed due to moisture. This is especially likely to happen when it's cold and the device heats up quickly.

Hi Jan,

I'm not entirely sure where this coating comes from. Bastion's theory about condensation sounds plausible, but it also seems that some kind of residue must have been stuck to the circuit board in its original state, which then reacted with the water and electricity.

But putting a circuit board with all its electronic components into ethanol? I would be cautious about that, because some of the insulating plastic layers could dissolve or, at the very least, swell. A quick rinse is probably okay, but I think soaking it for several hours is risky.

Does anyone know what solvent is used in electronic cleaning sprays?

Anyway, I think it's crazy that a device like that can break down and that you lose all mechanical control over its interior temperature. Thankfully, the rear windows are still manually operated, so even if the second electric window fails, at least those still work.

Oh yes, it's actually quite convenient here in the United Kingdom that we drive on the left. Now I don't have to open my broken driver's side window in the parking garage to get the ticket; I can do it through the (still) working passenger-side window.

I always use isopropyl alcohol (2-propanol). It doesn't cause any damage to me.

Is it possible that the climate control system, somewhere within the fan area that draws in cabin air, is blowing air directly onto the sensor? Something might have happened there. Otherwise, the description of condensation formation sounds very realistic.

matthiasTDI96 wrote:

I always use isopropanol (2-propanol). This stuff doesn't cause any damage to me.

Do you mean contact cleaner? Mine is like brake cleaner. I would be careful using that.

Where my radio reception was poor, I sprayed the threads of the antenna. The reception improved, but now the plastic/rubber coating on the antenna (where the outer thread is located) is disintegrating into small pieces. Every time I go to the car wash, some of it falls off the antenna. However, my antenna costs about EUR 90.00...

Hi,

Quote:

Is it possible that the climate control system, somewhere within the fan area that draws in cabin air, is blowing air directly onto the sensor? Something might have happened there. Otherwise, the description of condensation formation sounds very realistic.

The interior sensor (I'm not sure if the 6K model actually has a fan) is located much further to the left, under the steering column.

By the way, the temperature control system also fails if this great design of the outside temperature sensor in the right side mirror malfunctions. In that case, you can only operate it manually with the Hi/Lo settings. I experienced this last year when the first frost came, and the Ibiza thought it should turn on the AC because it "measured" an outside temperature of 37 degrees. If you haven't experienced this yet... it's likely to happen! The sensor is located in a plastic housing that is poorly sealed from above, and eventually water gets in. When it freezes, the seal breaks, allowing water to reach the contacts and change the resistance of the PTC heater. The solution from Seat is expensive, but scraping it out, drying it, and adding some two-component adhesive also works, without affecting the accuracy.

I'm also starting to worry about the eFH; it's been making some concerning noises lately. I suppose I'll have to take it apart and see what's wrong.

Best regards,

Jan.

Georg_G wrote:

By the way, this part costs approximately 360 euros from Seat.

The display unit for vehicles with air conditioning and an onboard computer costs €580, and the radio unit costs €480.

Jan6K wrote:

The interior sensor (I'm not sure if the 6K model actually has a fan) is located significantly further to the left, underneath the steering column.

Yes, he did. Since the car's heating system doesn't really work well in the winter, there's a relatively good solution: you can solder a suitable resistor in parallel with the existing heating element and make it "activatable" via a switch. This way, I essentially have a switch near the sensor for "summer/winter" mode. In the summer, it cools normally, and in the winter, it finally provides warm air inside, even at 21°C.

This means the car always starts with a slightly cooler interior, so it has to work harder to heat up. However, if you measure it with a thermometer, it will still reach the desired temperature within about 10 minutes in the winter.

In the summer, you need to manually turn it off using the switch for a simple reason: otherwise, the car thinks it's too cold and turns on the air conditioning too late.


I can also gladly find the relevant thread from the Ibiza forum if you'd like.


Greetings.
Georg.