Speedometer for Polo 6N Diesel 1998 1.9 TDI

Guys with electronics experience, I need your help...
Car:
Volkswagen Polo 6N 1.9 Diesel, 1998.
Engine: 1.9 TDI AFN

Problem: The tachometer is showing a reading that is much too low!

In the Polo, the signal from the LIMA (alternator) to the TDI engine is being sent via the ECU (engine control unit). The engine speed is too low... it only shows a reading at high engine speeds... but then the sensor shouldn't be faulty, right?

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

"gr. Tkr"

More precise description - perhaps that will help...

Engine: 1.9L R4 EDC G00SG 0801
Chassis type entered: 1H VW Golf III.
Scan Modules: 01, 02, 03, 08, 12, 15, 25, 41, 56.

Connected the TDI engine wiring harness and left the rest, along with the speedometer, etc., from the Polo.

1.) The tachometer is not working properly.
2.) 2 airbags with the following error message:
a.) 1224 - Control module does not match the vehicle (35-00)
b.) 0589 Airbag Igniter 1, Passenger Side (N131) 35-00
3.) Brake Pedals 00741 Brake Pedal Monitoring 27-00 - Implausible Signal.

Any tips (besides removing airbags)?

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

"gr. Tkr"

a) How about a full system scan?
b) What about diesel engines now, and what about gasoline engines?
hg
Herbert.

Herbert,

If I enter "Golf III", it should automatically recognize that it's a diesel. It's a Polo 6N with a Golf 3 TDI engine.

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

"gr. Tkr"

Install the remaining parts of the Golf III.

[Translating...]

Ha ha.

Herbert wrote:

How about a) a car scan...

and what parts from which car are installed or are supposed to be installed? Why don't they just say it plainly if only the engine from another car was put into the Polo? Where on earth is someone supposed to know what was cobbled together, they could just say it!

Install the speedometer from a Polo SDI/TDI. The speedometer from the WK diesel cannot process a tachometer signal from the MSTG.
Alternatively, you could reinstall the old timing belt pulley, but you would first need to check if the gear ratio would still be compatible with the TDI pulley.

Why enter "Golf III" (and where?), when it's supposed to be a Polo 6N with an AFN engine now?
The 6N model was available with an AFN engine. What type (engine code) was the original engine?
Which version of "VCDS" are you using?
hg
Herbert.

Tikra wrote:

Ha ha.

The ECU (engine control unit) from a Golf III can be fitted into a Polo 6N with some modifications, specifically by replacing the wiring harness.

But not with the 1998 models; they already have speedometers in the Golf 4 style with backlighting. That means they're no longer using the technology of the Golf 3, but rather the technology of the Lupo.
Reverting to the old speedometer would not be impossible, but it would involve more effort than simply replacing the wiring harness.

Yes and no, the model change happened in 1998.

Starting in 10/97, the 6N model used the MJ98, and from that point on, the new ZE was available.