1985 Alfa 90 ARC brake lights blinking.

Started by Dishy, March 29, 2023, 06:42:45 PM

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Hi All,
        As the title says I have the ARC brake pad/reservoir and stoplight warning lights blinking whenever I touch the brakes. A couple of years ago I replaced the voltage regulator and have checked the front and rear brake pad wear sensors are still shorted and not connected to ground. I have checked the brake fluid switch and brake fluid relay and both are working properly. I am stumped what the problem could be.

I am not sure if it could be related but the last thing I worked on was replacing the radiator, coolant hoses and heater hoses.

Any ideas appreciated



Have you checked the rear light cluster earth points in the boot.


Have you checked the brake pedal switch?

I had a 156 with a curious brake light issue once, turned out to be the switch on the actual pedal that was faulty (had reached its max. extension) and was occasionally making the brake lights flicker and come on, when no pressure on the pedal existed.  Caused the ABS to get confused and shut down all associated systems.

I went round in circles looking for blown bulbs, earths, yada yada.. until I realised the brake lamps were occasionally flashing and disabling cruise.

Just something else to look at.  No idea how complicated the brakes/abs on a 90 are.
Good luck 👍
'66 Duetto (lacework of doom)
'73 1600 GT Junior (ensconced)
'03 156 1.9JTD Sportwagon (daily driver)


Both are good starting points. I'd probably start with the earth in the boot and the earth for the third brake light. In my 75 I shortened the earth to the rear lights as it went all the way back to under the rear seats. Cut it short and created a new earth point close to the lights in the boot.

I have also had a brake light switch fail so well worth checking that too.


Hi All,
         Thanks for the ideas. I finally got a chance to check the brake switch and seems to be working properly. The big terminals are open till you push the pedal and the small terminals are the oposite closed until the brake pedal is pushed then it becomes open.
          I'll check the earth connection next.



Hi All,
         I have checked the earth's to the globes and everything measures about 0.5 Ohms. So I don't think I have any earth connection problems.