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Quick electrical question.

Quick electrical question.

 
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dieselsmoke300d
To many things I say: Bah Humbug!

65
05-10-2012, 12:50 PM #1
Hi all. I'm new on here.

I have an electrical issue in my '84 300D where the alternator just refuses to charge the battery sometimes. It's a brand new alternator so I doubt it's fried. And it was working for about two weeks after I put it in. And it still works occasionally. I noticed early on that two of the wires next to the alternator plug had arced and melted the insulation coating. So I fixed that, but no change. I thought it could've arced somewhere else and could be where the short is. My question is, is there anything between the alternator and the battery? Or is it a straight shot? If it is, then that could be my problem.

Thanks.

Matt.

'85 300SD Turbo
'92 Subaru SVX
'83 Pontiac Firebird S/E
'88 Pontiac Firebird
dieselsmoke300d
05-10-2012, 12:50 PM #1

Hi all. I'm new on here.

I have an electrical issue in my '84 300D where the alternator just refuses to charge the battery sometimes. It's a brand new alternator so I doubt it's fried. And it was working for about two weeks after I put it in. And it still works occasionally. I noticed early on that two of the wires next to the alternator plug had arced and melted the insulation coating. So I fixed that, but no change. I thought it could've arced somewhere else and could be where the short is. My question is, is there anything between the alternator and the battery? Or is it a straight shot? If it is, then that could be my problem.

Thanks.


Matt.

'85 300SD Turbo
'92 Subaru SVX
'83 Pontiac Firebird S/E
'88 Pontiac Firebird

Simpler=Better
PORTED HEAD

2,127
05-10-2012, 01:50 PM #2
Sounds like your "field activator thingy" isn't working right. It takes a little power to get the alternator fired up, an alternative is to spin it faster until it "catches".

Next time you drive it rev the engine up to 3,500-4,000 with the dash lights on, you should see them get a tad brighter all of the sudden. Then it's the field igniter thingy. I can't think of the technical term right now.

Newbie-read this: Cheap Tricks
617.952-220k-Getting built up
larsalan I guess I need to look at this stupid ass drip shit. What you have to like mess with those elements on the pump? What a fucking hassle. then use some wire to hold the throttle open or some shit?
Simpler=Better
05-10-2012, 01:50 PM #2

Sounds like your "field activator thingy" isn't working right. It takes a little power to get the alternator fired up, an alternative is to spin it faster until it "catches".

Next time you drive it rev the engine up to 3,500-4,000 with the dash lights on, you should see them get a tad brighter all of the sudden. Then it's the field igniter thingy. I can't think of the technical term right now.


Newbie-read this: Cheap Tricks
617.952-220k-Getting built up
larsalan I guess I need to look at this stupid ass drip shit. What you have to like mess with those elements on the pump? What a fucking hassle. then use some wire to hold the throttle open or some shit?

yankneck696
Build it so strong & blow it up good !!!

395
05-10-2012, 04:49 PM #3
With the "Arced out connectors", most likely they are just loose & heated up. Great that you replaced them. Check a wiring diagram & make sure they are right. With the heated up connections, you may need to find the reason it happened. Check ALL grounds, ALL "+ Positive Red" connections at battery or distribution blocks. Check wiring diagram to see if there are fusible links.

Basically, find the cause of the original problem before putting band-aids on your electrics.

Ed
yankneck696
05-10-2012, 04:49 PM #3

With the "Arced out connectors", most likely they are just loose & heated up. Great that you replaced them. Check a wiring diagram & make sure they are right. With the heated up connections, you may need to find the reason it happened. Check ALL grounds, ALL "+ Positive Red" connections at battery or distribution blocks. Check wiring diagram to see if there are fusible links.

Basically, find the cause of the original problem before putting band-aids on your electrics.

Ed

dieselsmoke300d
To many things I say: Bah Humbug!

65
05-21-2012, 01:24 AM #4
Sorry I took so long to reply. Thanks for the posts.

Ed@ The only thing I can think of that would've melted the wire insulation like that is if somebody crossed the terminals by accident or something. Could explain why both the battery and the alternator were shot when I bought it. And my "repair" was really no more than electrical tape.

Simpler=Better@ I didn't think such a thing existed in the car. Don't think that's the issue though. (I could be wrong idk). But thanks for the tip.

See the deal was it would either be working or not. Not in between. The battery would be reading around 14-ish volts, and then back to 12 when not working. I had a garage do a quick test and apparently meter wasn't getting anything from the alternator. Since like a day after I first posted, the alternator was working about 3/4 of the time for a whole week. Then one day I had some time to kill so I went for a drive on some country road. There was this little hill that I didn't see and I went over it at like 65mph and almost made the car jump. Since then the alternator hasn't worked at all.

So my guess is that it's just the wires that are shorting out.

Matt.

'85 300SD Turbo
'92 Subaru SVX
'83 Pontiac Firebird S/E
'88 Pontiac Firebird
dieselsmoke300d
05-21-2012, 01:24 AM #4

Sorry I took so long to reply. Thanks for the posts.

Ed@ The only thing I can think of that would've melted the wire insulation like that is if somebody crossed the terminals by accident or something. Could explain why both the battery and the alternator were shot when I bought it. And my "repair" was really no more than electrical tape.

Simpler=Better@ I didn't think such a thing existed in the car. Don't think that's the issue though. (I could be wrong idk). But thanks for the tip.

See the deal was it would either be working or not. Not in between. The battery would be reading around 14-ish volts, and then back to 12 when not working. I had a garage do a quick test and apparently meter wasn't getting anything from the alternator. Since like a day after I first posted, the alternator was working about 3/4 of the time for a whole week. Then one day I had some time to kill so I went for a drive on some country road. There was this little hill that I didn't see and I went over it at like 65mph and almost made the car jump. Since then the alternator hasn't worked at all.

So my guess is that it's just the wires that are shorting out.


Matt.

'85 300SD Turbo
'92 Subaru SVX
'83 Pontiac Firebird S/E
'88 Pontiac Firebird

Hercules
GT2559V

219
05-21-2012, 01:50 AM #5
While cranking engine ,starter can find ground through alternator if engine to frame ground is poor,found this a few times.
Hercules
05-21-2012, 01:50 AM #5

While cranking engine ,starter can find ground through alternator if engine to frame ground is poor,found this a few times.

dieselsmoke300d
To many things I say: Bah Humbug!

65
05-21-2012, 02:09 AM #6
Last I checked that ground was good. That reminds me I need to find and check all the other grounds. I tried to get the crappy pioneer radio to work and the wiring is crap. Got no voltage and the ground was reading at about 30 ohms... Yuck. I would seriously hate it if my main problem was actually like a dozen little problems working together....

Matt.

'85 300SD Turbo
'92 Subaru SVX
'83 Pontiac Firebird S/E
'88 Pontiac Firebird
dieselsmoke300d
05-21-2012, 02:09 AM #6

Last I checked that ground was good. That reminds me I need to find and check all the other grounds. I tried to get the crappy pioneer radio to work and the wiring is crap. Got no voltage and the ground was reading at about 30 ohms... Yuck. I would seriously hate it if my main problem was actually like a dozen little problems working together....


Matt.

'85 300SD Turbo
'92 Subaru SVX
'83 Pontiac Firebird S/E
'88 Pontiac Firebird

 
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