Wiring question...91 Mazda 929 clock

So my 1976 Fiat 124 came with a clock in the dash. They break easily and are expensive to fix. The clocks, I mean...

Anyway, I put in an almost-matching Volvo clock from the eighties. It died, too.

So now I have 3 cannisters, 2 veglia gauge faces, 3 sets of clock hands... and I bought a clock from a 91 Mazda 929 off ebay to build a working clock with. The Mazda clock has a big housing, but the actual mechanism is tiny. (The housing and the adjuster mechanism will be under the dash, I think.)

So the Mazda clock has 4 wires. Power, ground, dash lights, and ???

Anybody have an idea, a diagram, or a good grasp of mazda wiring color codes (assuming there are such)?

Thanks for the help. Matt

Constant power ,switched power, ground, lights

Why would a clock need switched power?

pres589 wrote: Why would a clock need switched power?

Illumination (thus also needing the lights wire).

pres589 wrote: Why would a clock need switched power?

If it didn't have switched power it would be constantly illuminated, and drain the battery (um assuming a digital clock).

So what's the light lead doing? Ground is common between the motor and the light, the motor has constant power, the light gets its own varied 0-12VDC+, right?

If it's digital the light lead dims the numbers.

Not digital. So yeah, I'm wondering what switched power would do, too.

I can't find a wiring schematic online in the two minutes I spent looking.

Original Fiat clock:

Volvo clock:

Mazda clock:

Heh i have one of these clocks too... But now i want a volvo clock.

So I googled again for an answer to this question, and the first result... was this thread.

Impressive, Google. Not helpful, but impressive.

Any ideas?

Matt

You're probably going to need to dig up the FSM. Might not be easy, there weren't a TON of these things out there.

I'll see what i can find tomorrow.

Thanks!

So, there are 4 wires into the clock: black, green, brown, and red.

Looking at the circuit board inside the case, where the wires are soldered on, there are some labels.

Black is labeled "GND", which is a good start.

Green is labeled "TNS." Tracing it on the circuit board, it appears to be a ground for the light socket, and possibly nothing else.

Brown is labeled "ILL" which I will hazard a guess stands for illumination, as that trace seems to head to the bulb socket on the circuit board. (I checked them as far as the socket with a voltage meter/continuity tester.)

The red wire is labeled "B"

B appears to connect to a resistor, which then leads... well, elsewhere on the board. My first guess would be B as 12v positive, unswitched, and leave TNS and ILL unattached, as I won't be using the light socket on the board.

Any warnings/better ideas, or reasons that the light would have its own ground?

Thanks

Matt

The light may have its own ground if its wired up like Autometer gauges. The light snaps into a plastic housing, cant ground though the plastic housing, and therefore needs its own ground.

The B+ and other ground are for the clock. Easy way to test, put an ohm meter across the suspected light leads, should read very close to 0 resistance. Pull the bulb out. Should read infinite resistance (open).

Have you looked at the Autometer clock options?

http://www.autometer.com/search_results.aspx?q=clock

I looked through the autometer things, and some of them might be close-ish.

But my wife took one of the fiat clocks to an alleged clock repair shop here in town, and he massacred it. So I already have a Fiat case, hands, and face, with the mechanism out. If that's not crying out to be an ill-advised, unnecessarily complex project, I don't know what is.

Matt