What's this then?

[LiamFD]

So removing the gauge cluster due to the odo dying and the rev counter acting up and I've found this black box thing bodged into the wiring, it's been spliced into the plug and had two ring terminals going to the flex track on the clocks.

My guts are saying either a speedo converter, limit defenser thing. Other than that, no idea .

 

[jack.am]

Looks like an incendiary device to me

 

[Jit]

Looks like an incendiary device to me

wrong, its a north korean tracking chip

 

[SullyKP]

Someone picked up the wrong tub when they potted those connectors...

 

[JonFD]

Looks pretty similar to what my old car had as a speedo converter, the km to mph things

 

[LiamFD]

That's my feeling as the speedo does work in mph

 

[LiamFD]

Someone picked up the wrong tub when they potted those connectors...

I know, I hate bodges like that, however they have been cut too close to the connector so I can't redo it. I'd have to repin the plug.

 

[JoeLanger]

I'd be confident that's a kmph to mph converter. Could just remove it and read it in km

 

[LiamFD]

I'll just leave it in then, I got my fingers burnt previously trying to rectify faults on the old engine loom. Ended up buying a new engine loom so don't want to go down that route again!

 

[casey]

Did you fix the techo and odo issues?

I've just fixed an odo issue (blank display in his case) for an FD owner and I suspect the tacho issue is a dead IC driver on the back of the gauge. The IC's are obsolete, but I'm working on replacing the function with a, cheap and readily available, Arduino microcontroller and suitable software.

You can see the work I've been doing on FD clusters here: https://mazdarotaryclub.com/forum/index.php?topic=85243.0

That topic (last page) includes details of the odo fix.

 

[JonFD]

Did you fix the techo and odo issues?

I've just fixed an odo issue (blank display in his case) for an FD owner and I suspect the tacho issue is a dead IC driver on the back of the gauge. The IC's are obsolete, but I'm working on replacing the function with a, cheap and readily available, Arduino microcontroller and suitable software.

You can see the work I've been doing on FD clusters here: https://mazdarotaryclub.com/forum/index.php?topic=85243.0

That topic (last page) includes details of the odo fix.

Cant believe I missed this, my current car came with the odo blank, so I swapped the milage chip to my previous cars clocks and ran with them

I've just skimmed that thread and read the odo fix, hats off to you for the circuitry diag skills

If its literally like a 12p fix for the other set I'll be a happy chappy lol - Im assuming any 3 pin 4.19MHZ ceramic resonator will do the job?

https://www.enrgtech.co.uk/product/...G5fZ4B1vqrBLZYVe0b8jiAOm6JNrPipAaAoFUEALw_wcB Like this one for example? (only did a 2 min google search etc)

 

[Paul-Knightsport]

12p check the date

 

[casey]

Cant believe I missed this, my current car came with the odo blank, so I swapped the milage chip to my previous cars clocks and ran with them

I've just skimmed that thread and read the odo fix, hats off to you for the circuitry diag skills

If its literally like a 12p fix for the other set I'll be a happy chappy lol - Im assuming any 3 pin 4.19MHZ ceramic resonator will do the job?

https://www.enrgtech.co.uk/product/...G5fZ4B1vqrBLZYVe0b8jiAOm6JNrPipAaAoFUEALw_wcB Like this one for example? (only did a 2 min google search etc)

Yep, that's exactly the part I used to fix the failed odo. 10 minutes to remove the failed one and solder in a replacement. But it took a few hours to track down that this component was the source of the problem. It's rare for crystals and ceramic resonators to fail in my experience, so unexpected, but an easy fix.

If you have a an oscilloscope just probe the pins on that component (supplies to clock signal to the NEC CPU) and look for a 4.19MHz sine wave signal. If absent, that's the cause of the problem.