2004 MAZDA 3, Other

Fail-safe

Brake is on

No history available vehicle purchased from Japan

None

Have this Mazda Demio 2003 model it is a Mazda 2 in some countries.
Transmission is a FN4A

The mechanics replaced the engine due to lack of servicing. Don’t know the history of the vehicle as it was imported from Japan. For all I know the fault could have been there before.

We have a problem with the Trans it goes into to fail safe mode and the hold light on the dash flashes. Check codes none found if you cycle the key off and back on it is back to normal for a while till it fail-safes again. Try many different scanners to pull codes even sent to Mazda to put their latest scanner on still no codes present.

Check all the sensors, wiring, earths and powers to the PCM all seem in spec. Replace PCM and ABS with a known good unit problem still there.

What I have noticed is it seems to fail-safe when the brake pedal is pressed. So I checked the brake light bulbs for the correct wattage all are correct Then I disconnected the brake wire at the last plug before it goes into the PCM and ABS system drove it for weeks like this and its find except for a 1-2 shift shock.

Now this is where I need some new direction.

What I know but correct me if I am wrong is the brake light signal is used for descending downhill to down shift the trans to save the brakes and also to stop the cruise control.

Is there any there any think else that I have missed?
The other thing I was thinking how can I improve the 1-2 shift shock?