Power Steering Repair Polo 9N - Code 01309

Hello,

I recently had a lengthy troubleshooting session with a Polo 9N where the power steering failed. There were numerous error codes, but one is persistent: 01309 - Control unit defective (J500). Previously, there were also issues with the steering angle sensor, as well as other problems unrelated to the power steering. After disconnecting the connectors to the power steering control unit, corrosion was found on the connector where the sensors are located; all other connectors appear to be fine. The connector has been cleaned and reconnected, plenty of fluid is present, and all fuses have been checked. Are there any further tips, considering that the control unit and pump are integrated?
I'll soon be ready to purchase a new pump.

I am open to suggestions, including recommendations for affordable places to buy such pumps.

Okay, so the problem with the Polo was never really resolved because the car was sold at that time.

"Yesterday, I had a Skoda Fabia with the exact same problem: 'No communication to the control unit'... The power steering warning light is constantly on, and the control unit is not accessible. What's strange in this case is that the power steering functions properly about 80% of the time. The battery charge level is sufficient; I checked that as a replacement. The connectors at the control unit are verschandeln and dry."
Okay, what could be the problem? Could there be a broken cable or something else? As I said, even though the warning light is on and there's an error message, the steering assist usually works as expected after about 10 attempts. However, it doesn't work at all during two of those starts... The car is 6 years old, so there's no warranty anymore, and the workshop is wondering if a replacement part is needed... Has anyone had any ideas in the meantime?

According to what I read in a Skoda forum, there's a belief that the wiring harnesses are prone to corrosion, and apparently, they were even replaced in some early Fabias. Where is the body control module located on this thing? Also, where does the wire coming from the power steering end, as it's responsible for communication. I couldn't see everything yesterday in the dark and rain... Does anyone have a wiring diagram handy...? ULF? --> Maybe you know, since it's basically just a Polo...

matthiasTDI96 wrote:

WHERE is the body control module located in this thing, or where does the line coming from the power steering end that is responsible for communication. I couldn't see everything yesterday in the dark and rain... Does anyone have a wiring diagram...? ULF? --> Maybe you do, but it's still just a Polo....

Hi Matthias,

In the 9N model, the Body Control Module (BCM), including the CAN gateway, is located approximately above the clutch pedal.

The communication with the steering system in the 9N occurs via CAN bus (wire colors: orange-brown and orange-black) using an 11-pin connector located in the fender well, connecting to the power steering control unit.

I have no idea if the same applies to the Fabia...

If there's absolutely nothing else that can be done, is there also an old-school steering system without power steering available (for the 9N)?

Hello Matthias,

Unfortunately, I don't have my wiring diagrams here right now, but based on my own experience, I can report a certain degree of low-speed dependency in the power steering assist. We never had any error codes stored, and there was never a warning light illuminated, but sometimes, when rolling out of the garage immediately after a warm start with a very low engine speed (around 650 rpm, which is the usual idle speed for a warm engine), the power steering momentarily fails for a fraction of a second, but then functions normally. With a cold start and an elevated idle speed, or a warm start with the air conditioning on (also with an elevated idle speed), it always works normally from the moment the engine starts.

Observe whether there's a speed-dependent behavior. You might want to try increasing the voltage. I think the (possibly still too low) on-board voltage is being transmitted from the vehicle's body control module. This thing works electrically and draws a lot of power, so it's possible that it shuts down preventively if the voltage is too low, in order to prevent the engine from stalling.

At Volkswagen, the changes started around 2003, but I'm not entirely sure when they began at Skoda.
What you definitely should check are the connectors, and especially the ground connection on the left front crossmember.
The mass terminals tend to corrode and rust easily, which can quickly trigger this error message.
or sometimes there's a little bit more or less steering assistance needed here and there .

Remove the mass point and check for corrosion on both sides.

"Good tip about the MA sensor values... I'll definitely check those out. I'll also try to locate the body control module. It's strange that the power steering sometimes doesn't work, as I mentioned. The yellow warning light is constantly on. I remember experiencing similar issues with the power steering on my old A2, where it would fail or not function properly at low engine speeds."

@VAGtuning: So you're saying that the communication error could actually be caused by a mass-related problem?

Yes, that could be the case. If the mass is not good, the voltage will drop significantly when the electric motor is running (high current leads to high voltage loss). This can affect its function, although an electric motor can still operate with a voltage lower than 10V; the electronics might not.

Yes, but the on-board voltage is perfectly fine. That was the first thing that was checked. Of course, if the ground strap is broken, that's my source of error. I'll remove the battery as soon as I see the Fabia again and then work my way underneath. I'll also locate the body control module and check the wiring connections.
Perhaps one of you has experience with the three connectors on the servo? I have to admit, I don't know much about Polos.

I meant the mass of the power steering pump, not the mass of the electrical system.

Okay, thanks to some good literature (thanks to the donor), I've traced everything. Checked Can high and Can low – all okay up to the body control module. All ground points have been meticulously cleaned, and a new battery has been installed as a replacement.
The problem persists. The power steering system is working almost all the time, but the warning light is on, communication is not possible, and the power steering control unit is unreachable.
So, the peripherals are fine, and the wiring harness looks very good.

Okay, so what do you guys think, should I start looking for a used one? Because it seems like the problem is now with the power steering control unit.

Crap thing.

matthiasTDI96 wrote:

The problem persists. The power steering is working almost all the time, but the warning light is on, communication is not possible, and the power steering control unit is unreachable. So, the peripherals are fine, and the wiring harness looks very good. Okay, so what do you say, should I look for a used one? Because now it seems like the problem is with the power steering control unit

.
Just to be sure: Is the servo also "enabled" in the CAN gateway through coding or configuration?

Yes, Ulf, that's it; I already looked into it... what a pain.

I read in a Skoda forum that people believe there are issues with corroded wiring harnesses, and apparently, this even led to replacements in some early Fabia models.

As far as I know, this change was implemented starting from MJ05. Otherwise, there will be a customer service measure (or action).

lordofazeroth wrote:

Quote: I read in a Skoda forum that people believe there are corroded wiring harnesses, and it apparently even happened with early Fabias, where they were sometimes replaced. As far as I know, it was changed starting with MJ05. Otherwise, there will be a customer service measure.

If the customer service measure involves partially handling the wiring harness, Matthias is already aware of it.

Okay, thanks to good literature (thanks to the donor), everything has been checked. Can h, Can l, all are fine up to the body control module.

Hello Matthias,

How did you test the CAN bus?
Have you seen any IDs?
The steering angle and vehicle speed are interesting factors here...

I've worked with a similar servo before, although it was a different model (a PQ 35).
When our gateway wasn't functioning correctly, we encountered the same error.

The control unit should ideally still function properly below 10V; otherwise, problems may occur.
In our case, the servo motor (SG) was directly connected to the steering system. Perhaps there's a problem with water getting into it?

Best regards, Jochen.