ARC Warning Lamps Alfa 75 TS

Started by bteoh, November 08, 2021, 05:00:22 PM

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I changed the voltage regulator on the alternator and removed the Laserline car alarm system (Thought I had a parasitic drain somewhere). However, I found that my ARC warning lamps are not working at all now. Also doesn't show if any of the doors are open on the screen. I double checked that everything is wired up ok and all the fuses are working. Even cleaned all the contacts in the fusebox but still no luck. Tried a spare ARC and N22 and that didn't work. (Not sure if my spare one is faulty also). Anyone encounter a not working ARC. Normally it is random flashing lights but mine is completely dead. Clock still works and green night illumination comes on when lights are switched on.

Colin Edwards

Could be the display - C11.  Do you have battery voltage across 7 & 8 at the connector on the rear of the display?
Do you have battery voltage at the ARC - N22 - Connector E across pins 1 & 2?
Do you have battery voltage at pins 1 & 2 on N22 - connector A?  Both should be at +12V.
Do you have a good ground at pin 7 on N22 - connector B?

Do you have the "Group 43" electrical schematics?

Checked and double checked EVERY ground connection - especially those on the door pillar near the fuse box? 

Has the 5V regulator on the N22/ARC pcb been upgraded?
2023 Tonale Veloce
2018 Abarth 124 Spider
1987 75 3.0

2020 Giulietta Veloce
2015 Giulietta QV
2009 159 3.2 Ti Q4
2012 Giulietta TCT Veloce
2006 147 Ti 2 door Selespeed
1979 Alfasud Ti 1.5


Now that the alarm is removed, does the car start?  Does the central locking work?

What did the alarm 'immobilise' before: fuel pump, combi relay, other?

As per Colin, I'd be checking voltage to the components, but knowing what the alarm did beforehand might provide some clues.  Perhaps wires were cut to remove it, but not rejoined?
Giulietta QV TCT . 1.75 TBi . Magnesio Grey - Black
GT . 3.2 V6 . Q2 . Kyalami Black - Red
75 . 3.0 V6 . Alfa Red - Grey


Thanks guys for the tips. Will continue to trouble shoot this problem. Now my overhead interior lamp stays on all the time. Previously, there was a delay timer that shuts it off a few seconds after the doors are closed / opened. When ignition is switched off, the lights turn off.
Colin, I shall check N22 for voltage. When I looked previously, the connector A had 12volts on the green/red wire and the grey/black wire. Will see what pin numbers they are when I check them again.
Richard, I think the alarm only had ignition cut out. The central locking all works ok with the key in the driver's door.