996 alternator wiring question

[Alex Kobi]

Hi guys,

 

 

 

I was doing the AOS replacement yesterday, and removed the alternator. At some point in the process I needed to connect the battery (🤦🏻) and the alternator power cable touched the engine 🤦🏻🤦🏻🤦🏻 and shorted for a sec.

 

I assembled everything, the car starts but the alternator doesn't charge (there is a gen/ batt warning on the dashboard).

 

I have checked the cables, some fuses and the current distributor. All seem to be ok. Any suggestions where to look next? Is there some relay that controls alternator/ starter?

(The alternator was outside the car, and it worked before disassembly :))

The car is '03 c2.

 

Thanks for the inputs

 

 

Edited April 26, 2022 by Alex Kobi

[JFP in PA]

You probably fried at least the voltage regulator in the alternator when you shorted it, and it needs to be replaced.

[Alex Kobi]

9 minutes ago, JFP in PA said:

You probably fried at least the voltage regulator in the alternator when you shorted it, and it needs to be replaced.

The alternator was out of the car at that moment

[JFP in PA]

There is a fusible link in the Power Distribution Box located on the firewall in the passengers footwell that has high amp fusible links inside; look there.

[Alex Kobi]

14 minutes ago, JFP in PA said:

There is a fusible link in the Power Distribution Box located on the firewall in the passengers footwell that has high amp fusible links inside; look there.

Yep, checked them too, all have continuity

[Alex Kobi]

Any idea what controls the exciter wire? Seems like the alternator doesn't get excited...

[JFP in PA]

57 minutes ago, Alex Kobi said:

Any idea what controls the exciter wire? Seems like the alternator doesn't get excited...

 

12 VDC from the battery.  Have you tested the alternator wire back to the battery for continuity and 12 V when the key is on?

[Alex Kobi]

1 hour ago, JFP in PA said:

 

12 VDC from the battery.  Have you tested the alternator wire back to the battery for continuity and 12 V when the key is on?

 

The thick cable behind the alternator is directly connected to the battery +ve? It still gives approx 12v.

Next will check the exciter wire with ignition on.

[Alex Kobi]

 

19 hours ago, JFP in PA said:

 

12 VDC from the battery.  Have you tested the alternator wire back to the battery for continuity and 12 V when the key is on?

Checked the exciter wire, it has switched 12v. When I check the alternator on the bench, when supplying 12v to exciter it doesn't get any harder to rotate (which I remember was the case in my mercedes alternator). And while rotating it with an impact gun it only gives out around 5v (maybe not rotating it fast enough...)

Anyways will replace the voltage regulator and test further... 

[Alex Kobi]

SORTED

Turned out to be a bad alternator after all, must have damaged it while jiggling it out of the car. Swapped an alternator from my c4s and all works. Fewf...

Thanks for all the inputs.

 

 

Edited April 28, 2022 by Alex Kobi

[JFP in PA]

Glad you got it sorted