Technical Diagonally opposite indicators not working

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Technical Diagonally opposite indicators not working

oninit

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Has anyone experienced this problem before? Today I took my Abarth Stilo for it's MOT and it failed. It failed on 2 indicator bulbs one is in the front passenger side and the other is in the rear drivers side cluster. so I struggled to get to the front indicator bulb only to find the bulb was fine. So I dismantled the rear light cluster and found that bulb was OK. So I thought it must be a fuse but I have been unable to find a fuse that protects only these 2 lamps. These 2 lamps do not work when setting the alarm or using the indicators or using the hazard warning lamps. Any help in tracing this fault would be happily received.
 
Surprised you didn't get any "bulb failure" warnings

It won't be a fuse as they're not really connected so it's likely to be two separate problems

ind circuit 1.JPG

I'd check for power at the light unit (F10 and F11 fronts and F30 and f31 rears) and check the earths at the units by a voltage drop check. There's also the possibility of the contact at the base of the bulb not making electrical contact through tarnishing so a good clean up of contacts with contact cleaner might do the job

ind circuit 2.JPG
 
I too was surprised about not getting the bulb failure warning, I have used a multimeter to measure volts at the front lamp holder and I get nothing. I also measured for continuity at the back of the bulb holder to make sure the bulb was making contact. I have a copy of the diagrams above I might try finding a 12 volt supply and applying it to the correct pin of the light cluster to ensure the lamp can light and the the earth connections are good. All other lights in each cluster work fine so I would be surprised if I have 2 earth faults that occured on the same day in 2 seperate light clusters but I will check. The only common components I can see from the diagram are the Body computer and the hazard warning switch.
 
Mysterious. The fact the BC isn't flagging "Bulb failure" is worrying.

I'd back probe for power on pin 5 on the front lights - looks like wire colour H and MN depending on which side. H=grey MN =brown/black but be aware Fiat wiring diags are often wrong

I can't see the hazard switch causing any of these problems but it's easy to disconnect it to eliminate it

Hope it's not the body computer playing up so next task might be to check for indicator power out at the BC pin 38 and pin 39 on connector B for front lights and 12 and 3 on connector D for the rears
 
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From experience the in out hazard switch is more
than likely quite crude copper contacts which bridge
2 other different lots of contacts. The contacts can become
burnt or dirty then won't switch correctly. Removing the hazard
switch wire loom normally means no indicator lights work at all,
directional or hazard.
It's been thrown in as a possible cause when all others have
been eliminated. I had to replace the bulbs in the ones on
my senator with LED's because the bulb had gone. I had to
take the switch apart to do so and thats when I had similar
problems.

John
 
Mysterious. The fact the BC isn't flagging "Bulb failure" is worrying.

I don't think the "Bulb failure" operates for indicator bulbs because you can tell a blown bulb from the green dash indicator flashing twice as fast. Not certain about the Stilo but that's the way it's been for other cars I've had with bulb failure units.

Dave.
 
It's different with the Stilo than older hazard switch and indicator switch designs. Older designs used to take the power directly to the various items

ind circuit 3.JPG
The Stilo hazard switch H20 AND the indicator switch H5 here simply supply an earth to the body computer telling it what to switch on eg hazards or left or right indicators and the body computer decides what needs switching on. They deal with extremely low power so the contacts don't burn like they used to in older designs

There is a circuit test at start up of the indicator circuits and bulbs and "lamp failure" should appear on an open circuit

There's no circuit test on the headlamps though

So, back to the plot
Are you sure there's no power arriving at the light units (back probe the supply wiring not just the bulb contacts)?

Are the side repeater indicator lights working?

You haven't done any mods like led lights or mirror indicator lights?
 
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I have carried out some more tests this evening, and it is looking more like the Body Computer that is at fault. I disconnected the hazard warning light switch and this had no effect, so this is not where the problem lies. I have checked the earth connections for each light cluster and these are good because if I apply a permanent 12 volts to the back of the lamp holder the light comes on. I have checked to see if there is power at the back of the lamp holders and there is not. The side repeaters do work.
 
You're welcome.

Looking grim though isn't it

Next task might be to check for indicator power out at the BC pin 38 and pin 39 on connector B for front lights and 12 and 3 on connector D for the rears. Might just be a bad connection at the body computer. Hope so

Check out connector F as that's main power in and then it's connectors B for fronts and D for rears. Wish you luck
 
I have some news. I needed to get the car to pass it's MOT so I have made a few small modifications. I used 2 12 volt relays and connected one relay to each of the side repeaters as these are still working. I then took a 12 volt supply to each relay, and then ran a new wire from each relay to the indicator that had failed. So now as the side repeaters come on the relay swithces on and so switches on the newly re wired indicator lamp. The car passed it's MOT so now I have a bit of time to decide what to do next. I did contact a local dealer who gave me a price of £350 to replace the body computer.
 
Hi ! i have almost the same problem...my turn signals don`t work..either hazard ones...i did check all the fuses and the electric circuit from the body computer to the bulbs...all ok...only the side signals work...:( what can i do in this case ?
please...help.
 
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