Flasher/Warnings CPU

[Casey]

Thanks to Kiwidave, who supplied a spare (possibly faulty) unit, I have been doing some investigative work on this module, tucked up on the panel near the driver's knee (UK model).

This is early analysis results, so excuse the quality of the diagrams, which I hope to refine and post up later.

Here is the unit in question, which seems to appear in versions A thro F (white lettering on the module). My investigation is on a version "E" module. Circuit board has been removed in this photo:

MCC_5688.JPG (155.3 KiB) Viewed 14884 times

It's a bit fiddly to remove as the three nuts holding it in place are a little hard to access. There is one large connector block and one smaller, single (or double on some versions I believe) connector. Once the three nuts are the two connections disconnected, it is easily removed.

3 rubber grommets hold a metal shield on the back of the unit in place. Slide these grommets off to remove the metal plate, then two self tapping screws hold the circuit board in place, Remove those screws and unclip the board from the edges of the casing to reveal:

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The next stage was to work out the components and circuit layout:

20210617_164656.jpg (171.57 KiB) Viewed 14884 times

This enabled me, with the help of the Mazda wiring diagrams, to work out 3/4 of the board functions, as marked:

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My rough circuit schematics to follow.....

[Casey]

These Mazda wiring diagrams helped to identify some of the external connections to the module. It's made harder as the diagrams cover functions not available on UK models, such as seatbelt warning buzzers, etc.

Wiring Diagram H.JPG (90.41 KiB) Viewed 14883 times

However, the letters M, C, K, J, G and E enabled me to sketch out this circuit and determine it provided an intermittent signal to the dashboard mounted buzzer to sound when a door was open and the car lights were left on (left hand part of the circuit below).

Additionally, the right hand part of the circuit provided a roughly 20-30 second "ground" to the ignition barrel light to illuminate the key area, triggered when a door was opened. I have managed to confirm these circuits and their operation by hooking up suitable inputs and outputs.

I'll tidy up this diagram later and post up a better version!

Door open, lights on and ignition cylinder light timer.jpg (148.91 KiB) Viewed 14883 times

[Casey]

This Mazda wiring diagram showed letters R, Q J and identified the componentry on the board relating to the hazard and flasher function:

2009-11-12_005812_diagram.gif (38.11 KiB) Viewed 14883 times

I traced the circuit connected to pins R, Q and J (J is a common "ground" for all the circuits):

Hazard and flasher control.jpg (108.95 KiB) Viewed 14883 times

I was able to hook up a 12 volt supply and a pair of 21w lamps to simulate the real load and confirmed the flasher functioned as expected

[Casey]

That just leaves the last circuit connecting to pins A, B, F, H and L on the module. I cannot find any reference to these pins in the Mazda wiring diagrams!!

I have traced the circuit:

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The relay contacts are not designed to carry as much current as the flasher relay, so I'm thinking it maybe it controls a load of maybe 10-15W? I've not had any joy in finding the spec for the "Taiko RGTB-007P" relay, suggesting it was a special component made for Mazda.

I would like to make up a test box to plug into these modules to test the functions I have identified (and the last function, when I've sorted it out!). The circuit components look to be easy to replace, so it should be relatively easy to repair faulty units. Worst case, a revised circuit using modern components is not out of the question.

To assist with making a tester, does anyone have any spare connectors that plug into this unit? Or does anyone know where I can source compatible plugs to connect to this module?

[A7RXY]

Fantastic info Malcolm, but me it all looks like ancient hieroglyphics found in a cave ... each to their own ...

[DKWW2000]

Will check over w/end Malcolm, Building new garage/workshop at the moment so my storage system consists of a big pile of things in the middle. I have built the new over the old thinking it would be easier, it is not!
Good work , mine is always playing up, have to wiggle connector about every 6 months

[gt_james]

I’ve just removed my flasher relay and tried one I borrowed from Jesse, so I have confirmed that is my problem. Now I have mine off the car I’ll have to see about fixing it, but it’s all a bit over my head. Maybe I can fit a generic flasher to replace the original and hope the rest of the board works.

[Casey]

Hi James - I can't see any reason why a generic unit couldn't be used with the switched battery from the wire into "Q" being used to control it, with the replacement flasher output fed to the wire on "R".

If I can obtain some connectors to rig up a tester, I might be able to set up a repair service for these modules

[Casey]

I’ve just removed my flasher relay and tried one I borrowed from Jesse, so I have confirmed that is my problem.

So you unplugged the large relay from the board and plugged in a replacement and it cured the fault?

It's just a single pole relay, so it should be possible to identify an electrical equivalent to replace it. The issue will be getting one with physically close pinouts to make replacement as easy as possible.

[gt_james]

No I changed the hole module. Now I know that it’s that, I could take one off one of my other cars and try de soldering and swapping components to track down the component which doesn’t work.