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Evening all. I could do with some help identifying which pins in the ecu go to the three knock sensors in our cars please. If anyone has the appropriate image or info.

I’m trying to resolve a knock sensor 3 G198 signal too small - intermittent issue on VCDS. I’ve replaced the knock sensor, which was a pain in the ass. The code is still there so time to look back in to the ecu and also check the resistance on all wires for knock sensors.

Unless anyone else has other suggestions

Assume you've checked the ground wire on it already?
(IIRC Knock sensors have 2 pins - 1 to the ECU and 1 to ground)

There are 3 to each sensor. And I don’t know which wires are what

Hope the attachment worked.

It’s a little blurred but I can make it out. Just got to work out what it all means. Cheers mate

Send your email and I can send you a clear copy if needed.

I seem to recall my service guide software (see the linky I think Shopp put in the DIY) has all with wiring diagrams in it

Plus, google Bosch 3 wire knock sensors and you’ll see some megasquirt guys are using it - so that should give you the pin outs, too

Mɐʇʇ wrote: ↑

Tue Jul 28, 2020 12:04 pm

I seem to recall my service guide software (see the linky I think Shopp put in the DIY) has all with wiring diagrams in it

Looked and can’t find it.

Cheers for your help so far guys. It was a little quiet before so was worried I was on my own

G198 knock sensor 3 has a wire going to 220 which is a ground in the engine bay.

A shared pin 99 for all sensors

And pin 31 on its own.

Looking at that I’m wondering if pin / wire 31 might be the issue as it’s the only wire on its own. The other two share the same wires as the other knock sensors so would have thought a fault there would trip all three

Lots of the other sensors will have a choke on them and therefore not be so sensitive to signal noise - but the knock sensor can't.
It is common practice to have sensor earths all go back to the ECU to a common earth there rather than the nearest ground point. Gotta be worth at least banging an ohmmeter on the 2x earths and seeing what you get.

Cheers. Will have a look tomorrow as been working