Dashboard instrument cluster information

[Casey]

All good information James

Odd about the buzzers. There are 2 sound generating devices on the back of the cluster. One is a huge "horn" like device for over-rev warning, the other is a much smaller sounder, which operates on low coolant level (maybe low oil level too). But both operate and sound correct when 12 volt DC is applied, so the presence of that oscillator is weird.

The circuit diagram for US spec cars shows an external oscillator driving a buzzer in the cluster, but as the buzzers I have operate from 12v DC, I had assumed it was one of the many differences between US and UK spec electrical.

I can't say I have spotted that oscillator down there, will take a look when I get back home. Can anyone else confirm they have an oscillator tucked away on the panel in front of the battery location? James' one clearly has "Oscillator" marked on the box, looks a bit like a relay.

[Casey]

The low fluid levels warning buzzer on the back of the cluster looks like this:

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20240423_111951.jpg (66.93 KiB) Viewed 11278 times

20240423_112004.jpg (123.25 KiB) Viewed 11278 times

It appears there is some sort of electronic circuitry on the PCB in this sounder. I'm presuming this is an oscillator circuit, as application of 12v DC creates the correct sound that I have heard for low coolant level in my S3.

[Hobbawobba]

I definitely had an oscillator when I stripped my loom. I can only find a picture of the plug end though. I believe it was located at the passenger side headlight. Next to the horn(?) relay. I'm trying to remember what was where now haha



I don't seem to remember my low coolant or oil level buzzer ever going off. I don't even think my low oil light came on when my rear plate cracked and left 500ml in my sump

[gt_james]

My low coolant light definitely works, and I think low oil light works, will check by unplugging the sender wire. For me its just the buzzer that doesn't seem to work. Jesse do you still have your oscillator?

That's the same plug yes.

[Casey]

I'd really love to know where those oscillators fit into the UK model spec electrics. They appear to be unnecessary, given there is an oscillator and sounder on the back of the dash.

The UK spec and US spec cluster PCB's are very different. I'm guessing the US spec "low level" sound emitting component is situated in the large silver "box" to the right of the picture?

UK Spec FB cluster PCB.jpg (126.87 KiB) Viewed 11255 times

US Spec FB cluster PCB.JPG (146.79 KiB) Viewed 11255 times

[Casey]

That is most useful, did you come across the trigger for the Over Rev Buzzer, mine has never worked despite checking pins etc?

Another thought on this Pete, but not the most likely cause of no over-rev buzzer. The trigger point is adjustable via a variable resistor, situated on the tacho PCB. With acknowledgement to "Iceman" on the rx7club.com forum:

...The over rev buzzer is adjustable by a pot on the back of the tach.

If you look at the circuit board on the back of the tach (not the gauges, but the actual tach itself- 4 screws and remove it from the gauge assembly to get to the circuit board).

Anyway on the circuit board there is two (yep that is 2) adjustment pots. You want the metal one. Each half turn is worth about 500 RPM.

But do not touch the plastic pot as that adjusts the calibration for the tach itself. Only the metal pot adjusts the calibration of the over rev...

The "metal" pot is VR2 to the left in this pic, just in view. VR1, the "plastic" pot is on the right.

FB Tacho PCB 2.jpg (87 KiB) Viewed 11249 times

[Hobbawobba]

My low coolant light definitely works, and I think low oil light works, will check by unplugging the sender wire. For me its just the buzzer that doesn't seem to work. Jesse do you still have your oscillator?

That's the same plug yes.

It's probably in the RX-7 footwell if you end up at the unit and want to have a look aye. Feel free to take it and send it to Malcolm if he wants . I don't know if I'll end up reinstalling it or not

I'd really love to know where those oscillators fit into the UK model spec electrics. They appear to be unnecessary, given there is an oscillator and sounder on the back of the dash.

I'm sure I looked in to the wiring when I stripped my loom. But it has been a few years now, I have forgotten everything about it

[DKWW2000]

Thanks Malcolm , I will have a Fettle, shame it cannot be accessed while in situ.