Need help. No power, after alternator replacement.

[Lmarche]

Few days ago the internal regulator/75amp/ Bosch alternator broke, it was time to replace it for a new Internal regulator/ 75 amp/ Valeo alternator.
I checked the wire connections, comparing and labeling with the previous, recheck them in a couple of posted discussions in this forum.
The double Red wire, is connected to the B+ 10mm, the multiple brown ground wires are connected to the same post opposite side B- 8mm, and the blue wire is connected to the lower 8mm. I charged the battery for 15 minutes with 10 amp.
When reconnecting the battery ground, I notice pop sound, couldn't recognize if it was from the cabin or the engine zone. the first bad indication was the front trunk light didn't turn on. Then I turned the ignition switch, but nothing happened, no cabin or instrument lights, no stereo, no buzzer, no even the honk works, of course no engine starting.
Then I disconnected the battery and checked voltage 12.2 V, I have checked all fuses front and engine zone, checked ignition switch is connected.
Any ideas?
911 SC 1982 Targa.

[targa80]

It seems you may have mis stepped when installing the alternator. Below is the schematic page for the Alternator and starter for your reference.
Two Red wires to terminal B+
Three Brown Wires to terminal D-
Blue wire to terminal D+/61

[Lmarche]

Originally Posted by targa80

It seems you may have mis stepped when installing the alternator. Below is the schematic page for the Alternator and starter for your reference.
Two Red wires to terminal B+
Three Brown Wires to terminal D-
Blue wire to terminal D+/61

This is how I connected it. Alternator labeling only shows + on one side and - on the other.


Thanks for your comments.

[john walker's workshop]

You can still start the car with all of the alternator wires just hanging there, so it's probably battery clamp related. Take them both off and clean the posts and inside the clamps before you delve into troubleshooting. Everything starts at the battery and travels out from there.

[Lmarche]

Update,
Reconnected the battery just to check Volts while connected, it when 2 V. Short suspected.
Then uninstalled the alternator, isolate the connectors, and connected the battery again, now there’s normal power to the rest of the car.
Didn’t attempted a start because a Short is obvious.
Does anybody see a mistake in how the alternator was connected?

[targa80]

I am surprised that the terminals are not clearly labeled except for the + on the diode pack.

[targa80]

The B+ terminal is obvious the D- and D+ are not I think you may have reversed the brown and blue wire terminals on the D side of alternator

[Lmarche]

Originally Posted by targa80

I am surprised that the terminals are not clearly labeled except for the + on the diode pack.

I think there isn’t much room for error to create a short, because the + 30 red hot battery wire is 10 mm,

[Superman]

Originally Posted by Lmarche

Update,
Reconnected the battery .....when 2 V. Short suspected.

Not sure I understand what happened here but if I knew for a fact there was a short in the system somewhere, I'd get out an Ohmmeter and find it. Starting with a resistance check between the Hot and Ground terminals on the alternator. Where the red and brown wires go.

It's not that hard to chase down a short, even in the whole complex system. Clip the - lead from the Ohmmeter to chassis ground and, starting with every system turned off and perhaps all the fuses removed, poke around and find out where there is not infinite resistance.

[Lmarche]

I just received a wiring draw from the alternator seller, who also has a work shop.
The connections on the new Valeo alternator are correct.
Has anyone bought a new alternator that shorts? I'm guessing the red Wire, because its hotwired, it doesn't blows any fuse.
thanks for your help I'm going to get another one.

[Lmarche]

Originally Posted by Superman

Not sure I understand what happened here but if I knew for a fact there was a short in the system somewhere, I'd get out an Ohmmeter and find it. Starting with a resistance check between the Hot and Ground terminals on the alternator. Where the red and brown wires go.

It's not that hard to chase down a short, even in the whole complex system. Clip the - lead from the Ohmmeter to chassis ground and, starting with every system turned off and perhaps all the fuses removed, poke around and find out where there is not infinite resistance.

Thanks for your comment, I will check resistance this evening.
Leo.

[Superman]

I think the fat red wire is directly connected to the battery. If the short is at the alternator end of that wire, then current is going to ground. There seems to be only two ways it can do this. It can go to ground using the brown (ground) wire or it can be shorting directly to the fan housing via the alternator case. With the alternator in situ and all wires disconnected, then test for resistance between the upper left and upper right terminals. If this shows infinite resistance, then test between the upper left terminal and the case of the alternator. If this also tests infinite resistance, then your alternator is not shorting the red wire to ground and if your system has a short, it is located somewhere else.

[Lmarche]

Hi Superman,
This are the readings:
On alternator connections
Red to Brown 1.0
Red to blue 1.0
Red to Core 1.0

Brown to core 0.0
Brown to blue 1.0

On wires to the alternator
Red to Brown 1.0 ( voltmeter indication increase until it stops at 1.0 ) maybe because same red wire connects to starter.
Red to Blue 1.0
Red to Engine 1.0

Brown to Blue 0.007
Brown to Engine 0.0

Blue to Engine 0.007

The Red cable and alternator connection don’t seem to make contact to ground. Maybe it made some contact to ground during install. Tomorrow I will try to install it again making sure no contact is evident.

Thanks.

[john walker's workshop]

If the fat positive wire gets grounded, there would be some serious smoke happening.

[GH85Carrera]

One of the solid reasons to take the old alternator to a local rebuild shop is you get the very same alternator back. Take a picture of the wires before removing them, and put them back in the same place. And you can have them use high quality bearings and avoid Chineesium bearings and parts. You will know what you have.

Of course if time is an issue, a replacement is always an option, but finding the same style is always a challenge.

[Lmarche]

This morning I reinstalled the alternator.
First connected the alternator wires, then reconnected the battery, no short indications. Then pull and played the wires a little and nothing, short was gone.
Then with battery disconnected reinstalled the fan and the rest of components, tried again connecting the battery and every thing good.
Finally charged the battery for 15 mins. Open the ignition switch and started the engine. Everything remained ok. With the engine started took volts readings, 13.8 V.
Took it for a ride with tools to disconnect the battery asap, but nothing. The car is back.
Thanks to all for your help, it’s amazing all the knowledge you guys transmit. Take care all.