QuestionHi Dave, England calling...
I have a 4yr old Alfa 146 1.6L.
The problem is a 10amp fuse (it's the one that protects the dash lights, front right sidelight, rear left sidelight and right rear plate light). The fuse has popped a couple of times in the 3 years that I've had the car, but this week it has taken to blowing frequently. Curiously, it holds up fine when the car is stationary, but as soon as I'm in motion its life expectancy is between 30 seconds and 2 minutes. I've hunted for a solution, and thought I had it when I found that the wiring to the rear plate light was wet, but even with that isolated the fuse continued to blow - no joy, no solution.
So, what so you think Dave, can you help? Thanks in advance, Trev.
AnswerHi Trevor,
I wish there was a magic potion I could send you. Electrical faults are difficult to troubleshoot when in person with all the test equipment available. Anything I offer from across the pond, on a car I've never seen except in pictures and film, is pure guesswork.
The quickest way to find your problem would be to install a 50 amp fuse and go for a drive. Follow the smoke and foul odor directly to the offending part or wire. Of course, where their is smoke there is fire, so this might be better moved to the bottom of the troubleshooting list. :)
There is only one thing that can cause a fuse to burn out. Amperage in excess of it's rating. Now, there you have it. Just find the reason and put it right.
I'm sorry... it's early on a Sunday morning and my sense of humor must have arisen before the rest of me.
What troubles me here is the fact that you said the problem existed from the beginning and has now gotten worse. You are describing a circuit that has a few light bulbs on it. Rather small ones at that. One would think that 10 amps would be sufficient to handle this load.
My suggestion for trouble shooting is as follows...
It's my feeling that you have one of two troubles. Either a faulty connection in the wires/bulb recepticles or other hardware, allowing a live lead to touch ground (I'm sorry, you chaps say "Earth" don't you?)
OR!!!! what I suspect, since it's not a new problem... is that there is a trim screw piercing the wiring bundle to the rear of the car. This is very common!!!
To find the source, you will need either a volt/ohm meter or a lot of fuses. You were on the right track by isolating the plate light. You need to isolate as much as possible. If you use a Volt/Ohm meter you won't need to use a new fuse to check your progress. Remove the fuse and put one lead of the Ohm meter to the "Load" side of the fuse block and the other to earth. You will be reading the total resistance of the bulbs in the cirucit, so don't expect it to show open or go to infinity.
You say it blows while driving. Since every bulb you describe is only on when the parking or headlights are on, I assume it doesn't blow the fuse with the lights off???? I'm curious if you turn on the lights without driving the car, if it would still blow. In other words... is it vibration related? I would think that the output of the Alternator (whoops, is it still a dymamo there?) wouldn't make any difference. Usually as voltage increases slightly with engine RPM, amperage actually goes down slightly.
I suggest you take each load (light bulb socket) apart and visually inspect it. Then you need to discover where the harness is routed. Sometimes it's through the roofline but more commonly through the door sill or rocker panel on the bottom. I would start by removing every trim screw you can find, one at a time and inspect them. If you remove a screw and the end of it is burned or shows some other sign of electrical arc, there is cause for excitement.
Remove every trim screw you can find along the path and drive it again. Remember if the wiring runs low in the car, there are trim screws on the kick panels under the dash (Facia). The most common culprits are those in the shiny metal sill kick plates along the bottom of the door opening. If the fuse doesn't blow then you will have to install one or two screws at at time and see what happens then. You can save some fuses if you use the ohm meter to determine when the short is eliminated. If this reveals no problem, then try disconnecting each load, like you did with the plate light. The instrument lights should have a single connector you can disconnect. That will isolate them as a group.
Trevor, I wish I had access to wiring diagrams, but they just never imported the 146 to North America. You seem to have some knowledge of how it all works, so I'm sure you can do as well as a professional mechanic. He would have to do basically the same thing as you but I think your time is cheaper than his. The only difference is, if it's a specific chronic problem that they have seen many times on your model. You might check with an experienced Alfa tech at a UK agency, or contact the Alfa Romeo Owner's Club of Great Britian. I used to talk to Ed McDonough, who was club president, but I'm not sure if he still is around. They have a website and might have some insight for you.
I know that a friend of mine who works for VW here and used to be a field tech for Alfa told me of a problem with one of the VW models. There was a trim screw in the rear plastic window trim that pierced the wire bundle in dozens of cars. Everytime the driver applied the brakes, the fuse would blow. They just left the screw out until the factory fixed the routing of the harness, and that was the end of the problem.
I'm sorry I can't be of more help. If you begin this time consuming chore or run into anything weird, please write me at <doc1590@yahoo.com> and I'll try to help.
Good luck,
dave
