Electrical Discharge Issue - Alfa Romeo Bulletin Board & Forums
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post #1 of 36 (permalink) Old 05-29-2016, 01:35 PM Thread Starter
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Electrical Discharge Issue

I recently purchased a 1990 Graduate and am having difficulty tracking down the source of current draw on the good battery. With all the circuit breakers pulled, the draw on the battery is 155 mA. There is a 28 mA draw off of circuit number 5 which I believe may be from the after-market radio. Where should I look for the amperage draw that is not circuited through the circuit breaker panel? The ECU? Any help would be appreciated.

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Spud
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post #2 of 36 (permalink) Old 05-29-2016, 01:45 PM
But Mad North-Northwest
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So the radio should be hooked up to unswitched power to preserve memory. It's possible something is wrong with the radio or the PO screwed up the wiring. I'd suggest pulling it out of the dash and unplugging it to rule it in/out.

Tom

1963 Giulia Spider (1750 engine)
1974 GTV
1991 Spider
Former: 1987 Milano Gold
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post #3 of 36 (permalink) Old 05-29-2016, 03:40 PM
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I took the liberty of moving this to the Spider section.

Something to check are the interior lights. The footwell lights have three options - automatic, always off, and always on. The lens is also the switch. Often they get kicked to the always on position which can go unnoticed.

- - Eric
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- -~ 1981 GTV-6 ~
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post #4 of 36 (permalink) Old 05-29-2016, 04:01 PM
But Mad North-Northwest
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Yeah, but the footwell lights are fused, right? If he's pulled the fuses and there's still a drain, then that's not it.

Tom

1963 Giulia Spider (1750 engine)
1974 GTV
1991 Spider
Former: 1987 Milano Gold
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post #5 of 36 (permalink) Old 05-29-2016, 04:09 PM Thread Starter
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Gubi,

Can you direct me to info on the procedure for pulling the radio? Does the radio operate on a different circuit, one that does not pass through the fuse box? Perhaps that is how this one was installed. Would appreciate knowing how to take out the radio so I could check it out.

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Spud
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post #6 of 36 (permalink) Old 05-29-2016, 04:21 PM
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It's a DIN mounting so it should just slide out when you insert a tool into each side. The stock radio uses u-shaped DIN tools pictured below. If yours is aftermarket, Mongo dunno: there may be a bezel you need to remove to access the slots first, and then you'll either need the tool below or some of the tab shaped tools.

Pull up the user manual for your radio online and it may have some details.
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Tom

1963 Giulia Spider (1750 engine)
1974 GTV
1991 Spider
Former: 1987 Milano Gold
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post #7 of 36 (permalink) Old 05-30-2016, 07:51 AM Thread Starter
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Thanks Gubi,

I went on-line for the tool to remove the radio. The radio is a Kenwood. The tool costs $1.27 and I need two, one for each side of the radio. I also called Car Toys to see if a universal type tool is available. I was told that O'Reilly's has them. So, to avoid waiting a week for Kenwood to ship me the tools, I thought I would check out the ones at O'Reilly's and go from there.

Thanks for your help. I hope the radio is the source of the amperage draw.

Spud
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post #8 of 36 (permalink) Old 06-08-2016, 07:51 PM Thread Starter
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Well, the radio has been removed. However, the amp discharge (with no fuses in the fuse panel) still persists. What other systems consume battery power outside those circuits that are fused in the fuse box? I don't know where to look next. Any suggestions would be greatly appreciated.

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Spud
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post #9 of 36 (permalink) Old 06-08-2016, 08:06 PM
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Geez. So gotta be something unswitched and unfused, right?

Bad diode in the alternator? That will leak current, I think. Maybe one of the relays behind the passenger seat is stuck closed? I'm reaching here...

Tom

1963 Giulia Spider (1750 engine)
1974 GTV
1991 Spider
Former: 1987 Milano Gold
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post #10 of 36 (permalink) Old 06-08-2016, 09:26 PM Thread Starter
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Gubi,

I have previously checked the alternator by disconnecting the red cable from the alternator at the connector that is located on the left side of the engine compartment. With it disconnected there was no change in the amperage draw. Is this the proper way to check to see if the problem is the diodes in the alternator?

I don't know anything about the relays. Where are they? How would I be able to check them?

By the way, thanks so much for taking the time to help me on this!

Spud
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post #11 of 36 (permalink) Old 06-08-2016, 09:46 PM
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Eh, I'm not being very helpful so far.

There's also a small green wire to the alternator that you should probably unplug at the same time as the big red one. I doubt that'll make a difference, but might as well be thorough.

Does the '90 have the little hatch behind the passenger seat? If so you can reach through that and pull the relays. If not you'll need to remove the rear deck cover. Keep track of the relays because they need to go back in the same locations.

Tom

1963 Giulia Spider (1750 engine)
1974 GTV
1991 Spider
Former: 1987 Milano Gold

Last edited by Gubi; 06-08-2016 at 10:11 PM. Reason: Typo
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post #12 of 36 (permalink) Old 06-09-2016, 12:17 AM
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lets recap a moment:
you have 155mA draw, which is 8 times what you should have (<20mA: radio memory and clock are only things that should be drawing)

you say fuse #5 (radio, indicators etc) draws 28mA
Does any other single fuse show a high draw other than #5?

when you remove ALL fuses, what mA draw do you have?

Id check under rear parcel shelf.
Main battery power (+) goes via isolated connector block G137 (on side of ECU carrier mount) and from there direct feed to:
pin #18 of ECU.......pull the big ECU connector plug and check! (carefully)
pin #30 of motronic 'red stripe' relay....pull the relay and check!
pin #30 of auxiliary relay (the one with the 15A fuse)......pull the relay and check!

The battery main power (+) also goes direct to the starter, then through the main (again, isolated) connector block on the inner fender and off from there.
Can a starter cause drain back, like an alternator can? dunno, tbh

Dom - Alfa Spider 1990 S4 - formerly: Alfa 101 Sprint, 2600 Sprint, Montreal - family classics: Jensen Interceptor II, '58 Hooper RR Silver Cloud I, Shadow II, '60 Corvette.

Last edited by spiderserie4; 06-09-2016 at 12:41 AM.
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post #13 of 36 (permalink) Old 06-09-2016, 09:43 AM Thread Starter
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Thank you Spiderseries 4!

Are you really in Germany?

fuse #5 is the only fused circuit that draws amperage.

With all the fuses out the amperage draw is 155 ma.

With fuse number 5 in, and the radio and clock removed the total amperage draw is 180 ma.

No other fused circuit draws amperage when fused.

I check the alternator for diode leakage by disconnecting the red cable from the alternator at the connector on the left side of the engine bay. I also disconnected the adjacent green wire.

I sequential removed the three relays under the rear parcel shelf. The amperage draw remains at 155 ma with each and all relays removed.

I have yet to check the starter. Is the connector block under the right rear fender? A possible defective armature that is somehow leaking current though the starter?

Perhaps: a faulty ignition switch? I don't know how I would check this. Do you think there is a possibility?

This amperage leak is certainly a challenging one!

Thanks to you and to all who are responding to this! You all are great!!

Spud
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post #14 of 36 (permalink) Old 06-09-2016, 10:44 AM
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Quote:
Originally Posted by Spud View Post
.....Are you really in Germany?
yep, Cologne!

Quote:
Originally Posted by Spud View Post
I have yet to check the starter. Is the connector block under the right rear fender?

no, the connector block I mentioned is the same one you already took the green wire off, for the alt.

but to really isolate the starter, I think you really need to pull the main lead off the starter, don't you?

here a page from the diagram (its for the S4 spider but same as your 90 S3, which is also motronic), if it is of use.

not sure if ignition switch could cause a drain, possible I guess (I am not a sparky!)
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File Type: pdf starting and charging.pdf (115.4 KB, 37 views)

Dom - Alfa Spider 1990 S4 - formerly: Alfa 101 Sprint, 2600 Sprint, Montreal - family classics: Jensen Interceptor II, '58 Hooper RR Silver Cloud I, Shadow II, '60 Corvette.
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post #15 of 36 (permalink) Old 06-09-2016, 10:48 AM
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Perhaps: a faulty ignition switch? I don't know how I would check this. Do you think there is a possibility?
I mean, it's *really* unlikely. But check to see if you have any voltage at all on the switched side of the fusebox with the key out, I suppose.

Maybe the starter? You'd need to disconnect the big wire to it and see if there's any continuity between the big bolt and ground.

(Note that the starter and alternator are direct-wired to the battery, so disconnect the battery before messing with either one. As you haven't killed yourself yet doing your testing I assume you know this, but just in case...)

On the Motronic cars like yours there should be a +12 always hot junction near the ECU behind the passenger seat. I think this just powers the relays so pulling the relay *should* have tested everything coming off of this, but I'm running out of other ideas...

Tom

1963 Giulia Spider (1750 engine)
1974 GTV
1991 Spider
Former: 1987 Milano Gold
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