What signals dies the Rev counter use to function?

[Derk vn]

Hi,

I have a B8 3.2 FSI V6 Quattro that ceased.

After searching for a engine in SA I had no choice but to do a conversion.

The car just broke 100k KLM.
So we fitted a Chev 5.7 V8 to the ZF 6HP28 Quattro Transmission.

So far all is fine and working BUT the Rev counter is not responding correctly.

We have tried everything...
* Original engine speed trigger wheel and sensor.

* 60-2 trigger with hall sensor

* Signal generators

Nothing the Rev counter just shivers and the ecu disconnects it...

My question is:

What all does the ECU require to to display the engine speed?

See Youtube link what it does

https://youtube.com/shorts/55OgrD6v4eo?feature=share

This is the only thing stopping us from finishing the project...

Please help me


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[Smac770]

The ECM is not involved in the display of the tachometer. That's the instrument cluster control module, J285. The instrument cluster module (CAN address 17) is like submitting a request for the engine speed PID from the ECM (CAN address 01) via the CAN bus. The only direct input signals to the J285 are the fuel level senders 1 and 2. Everything else comes in via CAN.

[Derk vn]

Thank you for your reply...

Problem is the Rev counter is shivering and not giving a reading no matter what we do...

Appart from the engine speed sensor is there anyother sensors involved to give a continues even reading?

The transmission is not will not select unless tackometer is working...


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[Smac770]

Nope. ECM reads engine speed sensor (aka crank position sensor) and thus knows engine speed. It's a value queried via CAN for whatever systems are interested. That said, I have no idea what you've wired up in this retrofit scenario. I know nothing about LS retrofits into a non-GM platform.

When you watch the instrument cluster measuring block 0 field 2 (engine speed), what do you see? This is the value that the tach needle is visualizing. The instrument cluster got this value from the ECM. That would be IDE00021 in my UDS Bosch MED17 ECM, but that's on my 2.0T engine. The 3.2L CALA engine in the B8 platform used Simos 8; PIDs in Simos 8 might look completely different (ok, looks like it's the same IDE00021, https://forums.ross-tech.com/index.php?threads/8767/)

When you use a scan tool to connect to CAN address 0x01 and query PID IDE00021, do you see a good stable engine speed value? No value? Unstable value?

[Derk vn]

Thank you very much for you reply...

I have an expert in his own right that is working on my car.

He understands your terminology...
Me not so much

He will communicate with you further on this chat.

Thank you very much for your assistance till now.
I realy appreciate it..




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