G70-Fehler => Ursache nicht aufzufinden | Posts 16+

Okay,

The error still exists. I have now obtained a wiring diagram and, instead of spending hours troubleshooting, it will be most efficient to replace all four wires.

A riddle just gave me a headache.

Three wires go directly to the 80plg engine control unit connector, which is fairly straightforward. However, a red/yellow wire with a 1mm² cross-section runs from the MAF sensor connector to "terminal 64" according to the VAG wiring diagram (which I printed out from SEAT's ELSA system, wiring diagram 60/4).

"Where is that location? Otherwise, I'll just rewire the three wires to the engine control unit first and hope that fixes the problem."


I would scan the service manual to clarify things and post it here, but I think that might violate some Volkswagen regulations, so I'll probably keep that expression to myself.



Edit: I've taken the liberty of moving this topic to the diesel engine technology section, as I think it fits better there.

Ibiza1986 wrote:

A red/yellow wire with a cross-sectional area of 1mm² runs from the MAF sensor connector to "terminal 64" according to the VAG wiring diagram (which I printed out from SEAT's ELSA system, wiring diagram 60/4). Where is this location?

I don't know, but if there are other wires converging at this connection point 64, it can only be a distribution point for ground or positive voltage.

On which pin number of the mass airflow sensor (MAF) is that particular wire located?

I've heard the term "frayed cable" before, and I actually saw one just last week (in my family's garage).

It should be relatively easy to find if that's the case.

ulf wrote:

I don't know that for sure, but if there are other wires converging at this connector pin 64, it can only be a distribution point for ground or positive voltage. On which pin number of the mass airflow sensor (MAF) is said wire located?

I also suspect a positive voltage for red/yellow, as the service manual indicates it's connected to pin 2 of the MAF sensor connector.

Tribu wrote:

I've heard about "shorted cables" before, and I actually saw one just last week (in the family garage). It should be easy to find if it is.

Unfortunately, the entire thing runs down into the engine wiring harness, so I would have to disassemble everything. Therefore, I think it will be faster if I just replace the wires. I can only trace the first 10 cm of the cable; after that, it disappears into the main wiring harness and is lost.

Ibiza1986 wrote:

Even with red/yellow signals, I tend to assume a positive voltage, as it's located on pin 2 of the MAF sensor connector according to the SLP.

According to my information, it's also the 12V supply for the MAF sensor. Therefore, you don't need to run an extra wire to the MSG; instead, you can connect it from the output of relay 109.

Okay, great, I'll get started on it. Performance-wise, I haven't noticed any issues at the moment, but that persistent error in the error log is really annoying.

I'm going crazy. All five wires are completely connected and working properly, even when I wiggle the wiring harness, and the pins on the MAF sensor connector and the engine control unit (ECU) connector are perfectly fine...

I'm at a loss.


Here's the translation:

"In summary:"


- LMM 3x getauscht (Bosch-Serien-LMM gegen Pierburg, Pierburg gegen orig. Bosch MAF sensors, etc.)
- Cables checked, no breaks in the wiring.
- The error persists.



Your advice? Should I ignore the errors? Or where should I continue searching?

Hi,

Sure, here is the translation of the text from German to English:

"Two questions:"

Do you still have any driving behavior issues, or are you just bothered by the error message?

Could it be that you still had the ignition on while you were disconnecting the MAF sensor connector – perhaps because you were fiddling around or taking measurements? In that case, a new error code might have been logged.

If you actually get the error again after deleting it and driving for a short distance, I would recommend logging the mass airflow sensor data during such a drive. It should briefly drop out, and you should be able to see that.

Have you ever installed four new cables? Measuring things can be tricky. Sometimes you encounter strange issues. For example, with the PD cable harnesses, measurements show no errors, but there's still a problem present.

If running new cables doesn't work either, then the problem is likely with the control unit itself.

Holger247 wrote:

Hi, Sure, here is the translation of the text from German to English: "Two questions:" Do you still have any driving behavior issues, or are you just bothered by the error message?

Actually, there are no driving behavior issues; the error message is just occurring sporadically... but it bothers me, my car should be perfect, okay?

Holger247 wrote:

Could it be that you still had the ignition on while you were disconnecting the MAF sensor connector – perhaps because you were fiddling around or taking measurements? In that case, a new error code might have been logged. If you actually get the error again after deleting it and driving for a short distance, I would log the mass airflow sensor data during such a trip. Then, there should be a brief interruption in the signal, and that should be visible.

No.

The error keeps recurring even when I delete it. Logging air mass data is always a tricky thing – because the error sometimes reappears after 10 km, and sometimes doesn't reappear at all for 500 km , but I can try it.

TDI-GTI-4-Motion wrote:

Have you ever installed 4 new cables? Measuring things can be tricky. Sometimes there are strange issues. For example, with the PD cable harnesses, measurements show absolutely no errors, and yet one is still present. If running new cables doesn't work either, then it can really only be a problem with the control unit itself.

I haven't installed any new cables yet because I haven't had the time. I understand your points; it can be difficult to reach all the areas for testing and troubleshooting.

I'll have to think about whether it's worth it to get new cables installed and deal with the hassle, especially since I don't currently have any complaints, and the car is running perfectly fine.

Just leave it as it is until the error can no longer be deleted. This way, you'll also be able to better pinpoint the actual source of the problem.
As long as everything is running smoothly and the TV isn't playing loud music, why stress yourself out about something you barely have time for anyway?

You can quickly check one more thing: Is the connector tight enough? You don't want it to be loose and cause problems. With the engine running, wiggle the connector and wiring harness – then read the error codes.

I assume that any issues caused by such fluctuations can only arise from the mass airflow sensor (MAF) itself, as the contacts on the engine control unit (ECU) are very tight and not subject to vibrations.

Okay, I'm going to go ahead and remove those four pins, cut them off, and press in new ones. Maybe that will solve the problem.

You don't think so? / Do you really think that?

The error persists; it now indicates that the "LMM signal is interrupted." What should I do?

Okay, the electrical connectors are fine. The mass airflow sensor (MAF) is an original Bosch/Seat part. The intake manifold seems to be okay so far, but there's a slight oil leak, and it's coming out very slowly from somewhere between the valve cover breather and the intake hose. This valve cover breather is connected to the intake hose leading to the turbo via a small hose...

Could that lead to the problem?

There's likely a broken wire somewhere between the mass airflow sensor (MAF) and the engine control unit (ECU). It's probably located near where you were working on the connector. Sometimes, the copper inside the cable can oxidize or break, causing an interruption. You might be able to pull out the defective cable by gently pulling on individual pins; the other cables that are in good condition should not come loose. This only works if the break is within about 50 cm (approximately 20 inches) of the connector.

Otherwise, use a multimeter to check for continuity at the ECU (STG) pins and MAF sensor (LMM) pins according to the wiring diagram.

*FINGERS CROSSED* that you find the bug.

hey,

Thank you for the tip .

I've checked the cables and they generally seem to be continuous, even when wiggling the wiring harness. My last idea is to completely replace the cables all the way to the engine control unit (ECU) and run them in parallel, because I can't get the old ones out of the tightly packed bundle without causing problems.

Normally, all the contacts from the mass airflow sensor (MAF) go directly to the engine control unit (ECU), right? That way, I can find the pin assignments in the wiring diagram.

"The funny thing is, I'm not experiencing any power issues. The car pulls cleanly and smoothly on a flat surface all the way up to 205 km/h (approximately 127 mph), which is fair considering the registered 193 km/h (approximately 120 mph). And otherwise, there's no surging or anything like that... that's why I'm so puzzled."

Hm, strange... I think that if it were my old AHF-TDI engine, the cable would probably go to a central connector, which is located on the right side of the cylinder head when viewed from the engine compartment; it's a thick, central rotating connector. If the cable runs through there, try wiggling/measuring it. Or maybe the MAF sensor is faulty! Try using another one for testing. It's curious that your car runs normally [/b].