Electrical head-scratcher - Alfa Romeo Bulletin Board & Forums

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post #1 of 13 (permalink) Old 03-18-2017, 03:16 PM Thread Starter
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Electrical head-scratcher

Patient is a 1982 GTV6

Symptoms:

Passenger front marker and parking lamp not functional, bulbs good.

Driver's rear marker and parking lamps not functional, bulbs good.

Rear license plate bulbs not functional, bulbs good.

Driver's rear brake lamp functions when pedal is pressed (along with passenger rear brake lamp, LOL).

Instrument panel lights light up fine.

Grounds seem to be good in all positions where lights are not working.

The wiring diagram is hard for me to decipher, but it seems like all these lamps are in the same power circuit.

Fuses in 9 and 10 are good (via multimeter).

Can someone please give me some further troubleshooting steps? Thanks!
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post #2 of 13 (permalink) Old 03-19-2017, 02:22 AM
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The lamps in question are powered thru fuse #9. If the fuse checks good, then the fuse contacts may be dirty. Simply pull the fuse, clean the contacts with a pencil eraser and squeeze the contacts together a bit (to provide more tension on the fuse).
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Jim

Series 2 USA 1750 GTV (in Series 1 European clothing)
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post #3 of 13 (permalink) Old 03-19-2017, 04:44 AM
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Papajam's reply is very likely correct. Many of the fuses have an Alu element which corrodes at the contact points with the fuse holder giving rise to an impaired or zero connection. Fuses with brass elements are much better in this regard. Contact enhancing paste or spray can also help.
Check with your multimeter that 12v is present on both sides of the fuse (9) when the lights should be lit, also check 12v at the lampholders.
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post #4 of 13 (permalink) Old 03-19-2017, 03:08 PM Thread Starter
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Closing the circle (circuit):

The fuse was indeed the problem. It checked out as continuous. In place, it was firm in between the contacts. No joy. Replaced with a ceramic-bodied, brass-conductor fuse. All the mentioned lights now function.

The take-away: Just because a fuse conducts electricity enough to make the multimeter give a satisfied "beep!" does not mean the fuse is good enough to run an automotive circuit.
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Last edited by nemesis; 03-19-2017 at 03:41 PM.
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post #5 of 13 (permalink) Old 03-19-2017, 10:00 PM
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I am convinced from first hand experience, that if all Alfa owners pulled those corroded overheated aluminum fuses tomorrow, cleaned the contact fingers and replaced them with copper and/or brass fuses, these kind of posts would drop by 75%.
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post #6 of 13 (permalink) Old 03-22-2017, 09:18 AM Thread Starter
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Quote:
Originally Posted by alfaloco View Post
I am convinced from first hand experience, that if all Alfa owners pulled those corroded overheated aluminum fuses tomorrow, cleaned the contact fingers and replaced them with copper and/or brass fuses, these kind of posts would drop by 75%.
This is the truth. Since I didn't have enough of the right kind of fuses to do this job, I didn't do it when I posted my fix. But I immediately ordered enough to get it done and have plenty left over. I will do exactly as you suggest, and also use a squirt of Deoxit D5 on each contact. I consider this preventative maintenance, and I might add it to my 60k-mile schedule. Every 60k, do this exact thing. Cheap, easy. And since I daily this car, the next 60k isn't that far off. Four years, really.
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post #7 of 13 (permalink) Old 03-22-2017, 09:26 AM
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Since we did the electrical PM work on Mike's car back in the fall of 2014, he has had ZERO electrical weird stuff happen with his GTV 6. Nothing. All the aluminum fuses that came with the car... we pitched in the trash.

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post #8 of 13 (permalink) Old 03-22-2017, 12:24 PM
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Of all of the problems people have with their Alfas, most are electrical in nature, usually caused by dirty/tarnished/corroded connections in the wires, switches, and fuse installations. My original Alfa, the 64 Giulia Sprint GT, always had problems because the fuse box was in the engine bay, not inside the cabin. the worst case of failures I've run across. Those fuses usually got very filthy and were always giving problems. Nothing like having the headlights go out because of dirty fuses. I finally wrapped the box in plastic, and that helped a lot.

For the later Alfas, seems that many of the wiring connections, esp in the engine bay, were subject to tarnishing/corrosion/dirtiness, and thus not conducting, sometimes irritatingly intermittent, so much that Alfa payed for the cleaning and protection labor by mechanics in many cases and models. And we are all familar with the switches for the 164 seats and windows, the switches being of a certain quality/design, that they were more susceptible to failure than those of most other marks it has seemed.
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89 Milano (wife's daily driver since 1989, Shankle Sport)
91 164S (my daily driver since 1994)
94 164LS (~Q) (trip Alfa since 2000)
72 Morgan 27 (water time since 1976)

previously owned since 1964:

62 Morris MiniMinor 850, 67 Austin 1275 Cooper S (Downton 3/4 race), 64 Giulia Sprint GT (1st red one made), 72 Fiat 128 Sedan, 75 Alfetta Sedan, 78 Alfetta Sedan, 78 GTV, 81 GTV6, 86 GTV6

Last edited by Del; 03-22-2017 at 12:54 PM.
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post #9 of 13 (permalink) Old 03-22-2017, 01:11 PM
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Aluminum and brass (the fuse holder contacts!!) are known galvanic reactors - they corrode in contact with each other!
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50 years from now - how is anyone going to restore a "classic" microprocessor based modern car??
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post #10 of 13 (permalink) Old 03-22-2017, 01:24 PM
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Wow! So based on the chart posted by Bruce, aluminum is the worst fuse link material you can use in contact with brass or copper. Nuff said, right? This info ought to be plastered all over this forum AND the tech forum, frankly! Or maybe stickies...

Señores administrators???
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post #11 of 13 (permalink) Old Yesterday, 07:03 AM
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I found out the hard way. Use copper or brass fuses. Those aluminum ones from the parts store are no good.
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post #12 of 13 (permalink) Old Yesterday, 09:58 AM
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Quote:
Originally Posted by italcarnut View Post
I found out the hard way. Use copper or brass fuses. Those aluminum ones from the parts store are no good.
Yup-- that's why you often see the links warped on the aluminum fuses. It's from the heat, and the heat comes from resistance building on the ends, from corrosion!

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post #13 of 13 (permalink) Old Yesterday, 11:13 AM
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Aluminum house wiring was also a disaster, with more than a few houses catching fire from the over heating connections. Friend of mine had that in his new house, at the time, and had more than one blackened plug socket box. Had to go through the house, take each box apart, and apply the special goop to prevent that resistance buildup and heat.

I suppose that goop would work if you couldn't find the good fuses, not that I'm suggesting that.

Del

Seattle

89 Milano (wife's daily driver since 1989, Shankle Sport)
91 164S (my daily driver since 1994)
94 164LS (~Q) (trip Alfa since 2000)
72 Morgan 27 (water time since 1976)

previously owned since 1964:

62 Morris MiniMinor 850, 67 Austin 1275 Cooper S (Downton 3/4 race), 64 Giulia Sprint GT (1st red one made), 72 Fiat 128 Sedan, 75 Alfetta Sedan, 78 Alfetta Sedan, 78 GTV, 81 GTV6, 86 GTV6
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