HELP: Strange intermittent S4 electrical issue

[cmbenedict]

1991 Spider has just developed some strange behavior that I am hoping someone may be familiar with.

1st event: On Wednesday, when in stop and go traffic, all dash lights came on, tach was jumping around and radio cut out (I think I had headlights on at time but unsure). Went away then came back and car died. It restarted right away and was fine for rest of journey.

2nd event: on way home all was well until I turned on headlights - same result. All dash lights flashed, tach jumped and radio cut out. Immediately turned off headlights and all returned to normal - car kept running. A few minutes later forced to turn lights on as getting dark - no probs. Flawless performance rest of way home.

3rd event: Yesterday, wife running around town, middle of day, no headlights in use. While waiting at traffic light, all dash lights came on and car died. Restarted right away with no further incident although she thought she smelled something electrical burning.

I have not had the chance to look at anything (fuses, etc) yet but plan to look at it this weekend. Does this type of behavior sound familiar to anyone? Any recommendations on what steps I should take to begin to diagnose? How scared should I be?

Please note I am a bit of a novice (have done minor repairs/maintenance over the years but nothing extensive) when it comes to mechanicals so don't hesitate to use small words.

Thanks in advance.
Chris

[ghnl]

I can't help with anything specific to your S4 Spider. My first thought however is to check all battery connections including the ground cable's connection to the body. (in our S3 the ground cable bolts to the trunk floor near the battery)

Then move up under the hood and clean & tighten all ground connections. Typically these are black wires bolted to the engine block or body work.

Finally use flashlight and peek up under the dash for more grounds.

Don't trust that any of these connections are OK just because they look OK or feel tight. Remove them (one at a time) clean the wire terminals and the area where they attach, then re-attach. I use a small toothbrush sized wire brush to clean the terminals & connecting areas. I like to add a dab of di-electric grease to stave off corrosion. You can buy small tube of di-electric grease at an auto supply store - it is also sold as 'tune-up grease'.

[Ren]

You should get your battery checked out to make sure it is holding a charge and the cells are ok. Then follow the advice given by ghnl. Another thing you should check is that the alternator is giving out the correct voltage. From what you say it could be earth related so you need to make 120% sure on the connections.
The 3rd event when a burning smell was detected is worrying. Do as best a visual check as you can on all the visible cables in the engine compartment and around the fuse-box.
I am sorry to say that electrical problems can be notoriously difficult to find even for experts. Let us know how you get on.

[Gubi]

Ignition switch going, perhaps? That might explain the burning smell.

[cmbenedict]

Thanks for the support and suggestions so far.

Quote:

Originally Posted by ghnl I can't help with anything specific to your S4 Spider. My first thought however is to check all battery connections including the ground cable's connection to the body. (in our S3 the ground cable bolts to the trunk floor near the battery) Then move up under the hood and clean & tighten all ground connections. Typically these are black wires bolted to the engine block or body work. Finally use flashlight and peek up under the dash for more grounds. Don't trust that any of these connections are OK just because they look OK or feel tight. Remove them (one at a time) clean the wire terminals and the area where they attach, then re-attach. I use a small toothbrush sized wire brush to clean the terminals & connecting areas. I like to add a dab of di-electric grease to stave off corrosion. You can buy small tube of di-electric grease at an auto supply store - it is also sold as 'tune-up grease'.

[ghnl]

If the S4 ignition switch is the same as the S3 (I presume it is), here's the continuity checks. Keep in mind that intermittant problems are the hardest to find.

[cmbenedict]

Thanks Eric. Will look at the ignition if problem continues.

Update - took car to my regular mechanic this morning. Lucked out as he works only 1 Saturday a month. Asked him to check the battery and alternator. First found that negative battery cable was loose and was easily wiggled off. Tightened it up and checked system. Was reading between 12.5 and 13 volts and would clearly drop when I turned on the lights and wipers (dash voltmeter deflected as well). He believes that it should be reading approx 14 volts but admitted he was not familiar with what the "average Alfa" should read. I shut car off so we could check tension on belt - looked good.

Diagnosis - alternator failing and needs to be replaced. Can anyone confirm what the voltage should be and does a replacement sound logical?

To make things more interesting, car would not restart as soon as he walked away - no power. I wiggled negative cable and power came back. Started up and I headed home to clean up connection. Turns out 1) the car had one of those "Green Knobs" installed (disconnects power for storage or as a theft deterrent) - the connection between the neg cable and the knob setup was loose, and 2) the positive cable was loose as well.

Removed the knob setup to eliminate it as a potential issue. Wire brushed clamps and battery terminals, reconnected all (with a good dollop of dielectric grease)and have taken a couple of short trips around town without incident. I am hoping that the multiple loose battery connections were the culprits. If anything pops up I will post again.

Thanks for the responses and the advice. I have had other cars wiggle a cable or clamp loose and never had such a dramatic dashboard response - cars simply wouldn't start. Guess I should have checked then first thing . Glad to be part of such a great community and hope I can pay it forward at some time.

[ghnl]

I second the notion to remove that battery disconnect device. I use them when working on the car to make it quick & easy to disconnect the battery but in daily use it only adds another potential failure point (and our cars need less potential problems...). Also, the cheap copies of those disconnects are very unreliable.