Reading speedo pulses

[Grrrmachine]

I know the sensor from the diff goes up to the cluster and through the ECU, but is there anywhere I can "tap in" to that pulse signal, so that I can plug in a multimeter while driving?

Somewhere like a plug used by the OBC, or a point on the back of the speedo?

[Brianmoooore]

The pins on the green connector on the back of the speedo are a speed output signal. They are used for cruise control and controlling the volume of the radio.

[Grrrmachine]

Thanks Brian. I found the colour of the wire to be brown/red, and traced that from the yellow plug on the back of the dash to the small 12-pin green plug for the 6-button OBC. Took my readings from there, and it all works wonders.

That OBC plug has eight other wires coming from it. Do you possibly have the wiring diagram that would tell me what each of those wires is? Colours are:

BLUE -
GREY/RED -
GREY/VIOLET -
BROWN/BLUE -
BROWN/YELLOW -
BROWN/WHITE -
RED/WHITE -

and a brown earth. I'm guessing one or even two would be fuel level senders, and one to the outside temp sensor...

[Brianmoooore]

You seem to have found the correct wire, but not where I said!
There are four sockets on the back of an E30 instrument cluster - the blue one (A), the white one (B), the yellow one (C), and a green one (F).
Confusion has arisen here, because the plastic frame of the green socket isn't always fitted, and if it isn't fitted, you won't know it's a green socket, and possibly won't notice that there is a socket there, although the buckets of the socket where the plug pins push in are always there.
The green plastic frame clips on to the bottom of the speedo area on the back of the cluster.

[Grrrmachine]

That's fantastic willnz, thankyou. It's a shame I didn't find what I was hoping for though...

I'm looking for wires that we transmitting tacho pulse, fuel level and coolant temp. Do any of those come out of the back of the yellow plug too, or anywhere else accesible?

Brian, yes, I know about the OTHER green socket you're talking about, but it was easier to access the speedo pulse for me as I've taken the OBC out already and replaced it with something a bit larger, so that plug was empty.

[Grrrmachine]

Superb willnz! Thank you!

[MrAsp]

You seem to have found the correct wire, but not where I said!
There are four sockets on the back of an E30 instrument cluster - the blue one (A), the white one (B), the yellow one (C), and a green one (F).
Confusion has arisen here, because the plastic frame of the green socket isn't always fitted, and if it isn't fitted, you won't know it's a green socket, and possibly won't notice that there is a socket there, although the buckets of the socket where the plug pins push in are always there.
The green plastic frame clips on to the bottom of the speedo area on the back of the cluster.

Interesting post!

Can you tell me what is the pin that brings the speedo signal into the cluster from the diff?

I know it is in the blue (or white) plug, but what is the right pin?

Thanks in advance!

[MrAsp]

Two wires, a brown and a brown/red coming into the cluster via pins 8 and 12 on the white plug.

Thank you willnz!