911 SC Charging problems
02-04-2017, 10:43 AM
#1
Track Day
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911 SC Charging problems
Hi Everyone, I hope someone can assist as I have read quite a bit, about the charging system, and still cannot address my problem.
Mine unit is a 911 SC Targa 1982. Car was giving charging problems and I took to the repair shop to have the engine rebuilt. After a couple of months, I have the car back with a nice running engine, but the guy could not figure the charging problem yet. When I picked up the car he said we need to replace the voltage regulator, because it was not charging at all, and the BATT LIGHT was not turning when the key is on the ignition position. I did replace the Voltage regulator last Wednesday,and guess what? Still no charge.
Right now I noticed the bulb socket needs to be replaced, but I will like to ask the following questions to see if I can address the issue.
1. From the wiring diagram, I noticed there is a Red/Black cable that has a 12V signal when the key is on IGNITION. then this Red Black cable connects into the bulb socket and the other end of the socket is a "BLUE" cable that goes into the voltage regulator. Is the previous statement correct? Can anybody confirm the cable color as I have a Blue/Green and another Blue cable on the car cluster?
2. I were reading the alternator needs to be excited to start generating, how does this exactly happens? Some lecture points the alternator needs a magnetic field to be excited, and then start charging?
3. Can I have the Part. No. of the socket for the battery light, since I really need a replacement. Can't seem to find it on Pelican, Vertex, etc.
At this point after what I've paid for the engine rebuild, I dont really car if I have to buy a new Alternator, I just want the car fixed to be able to enjoy it. I were running a precision rally last week, and had to abort the event, because the battery died
Something I noticed is, the battery light comes up on high revving, lets say aroung 3,000 and 5,000 sporadically, the battery light comes ON altogheter with the OXS light. I have the bulb unplugged now because the socket is worn but as said above, any guide, help in this matter will be really appreciated.
Thanks in advance,
Abdiel
Mine unit is a 911 SC Targa 1982. Car was giving charging problems and I took to the repair shop to have the engine rebuilt. After a couple of months, I have the car back with a nice running engine, but the guy could not figure the charging problem yet. When I picked up the car he said we need to replace the voltage regulator, because it was not charging at all, and the BATT LIGHT was not turning when the key is on the ignition position. I did replace the Voltage regulator last Wednesday,and guess what? Still no charge.
Right now I noticed the bulb socket needs to be replaced, but I will like to ask the following questions to see if I can address the issue.
1. From the wiring diagram, I noticed there is a Red/Black cable that has a 12V signal when the key is on IGNITION. then this Red Black cable connects into the bulb socket and the other end of the socket is a "BLUE" cable that goes into the voltage regulator. Is the previous statement correct? Can anybody confirm the cable color as I have a Blue/Green and another Blue cable on the car cluster?
2. I were reading the alternator needs to be excited to start generating, how does this exactly happens? Some lecture points the alternator needs a magnetic field to be excited, and then start charging?
3. Can I have the Part. No. of the socket for the battery light, since I really need a replacement. Can't seem to find it on Pelican, Vertex, etc.
At this point after what I've paid for the engine rebuild, I dont really car if I have to buy a new Alternator, I just want the car fixed to be able to enjoy it. I were running a precision rally last week, and had to abort the event, because the battery died
Something I noticed is, the battery light comes up on high revving, lets say aroung 3,000 and 5,000 sporadically, the battery light comes ON altogheter with the OXS light. I have the bulb unplugged now because the socket is worn but as said above, any guide, help in this matter will be really appreciated.
Thanks in advance,
Abdiel
Last edited by Abdiel Gonzalez; 02-04-2017 at 12:32 PM.
02-04-2017, 05:26 PM
#2
I haddah Google dat
Rennlist Member
Rennlist Member
You could have a bad alternator. I would take it out, and have it tested. If you use your old one as a core, and buy a rebuilt one, take the voltage regulator out and keep it as a spare.
02-07-2017, 12:33 PM
#3
Rennlist Member
Hello, don't know if you've made any progress on your charging issue yet or not so thought I'd try to address a few of your questions.
1. Yes the Red/Black wire should be switched ignition power. You should get 12V at the Red/Black wire with the key in the run position. This should supply power to the bulb socket for the Alternator charge indicator light.
The other terminal on the bulb socket should be attached to a Blue wire as you note. This wire should then run back to the D+ terminal of the voltage regulator. There is also a Blue/Green wire attached to this terminal. Without the engine running both of these wires should ground through the regulator to illuminate the Alt and OXS (Blue/Green wire) lights as the initial test indication for the bulbs. You can disconnect the Blue/Green wire and it should not affect the alternator’s ability to charge (you may want to unplug to isolate the charging system from the OXS system for troubleshooting).
2. The alternator needs to have the field excited to begin charging. This is accomplished through the power supplied by the Red/Black wire through the indicator bulb then through the Blue wire to the voltage regulator. If the indicator light does not illuminate with the key turned to run and the engine not started, there is a problem in the system.
A. Check for 12V on the Red/Black.
B. Check continuity through bulb socket and bulb, test bulb.
C. Check continuity to ground via blue (at bulb socket connector) wire through voltage regulator.
If “C” fails, remove blue wire at regulator and ground to engine to see if Alt Indicator light illuminates. (May want to have a fuse inline when you ground just in case there is an issue so you protect your wire harness)
3. I think the bulb socket is part number 999.632.007.00
Let me know what you find and I'll see if I can help further.
Good luck,
1. Yes the Red/Black wire should be switched ignition power. You should get 12V at the Red/Black wire with the key in the run position. This should supply power to the bulb socket for the Alternator charge indicator light.
The other terminal on the bulb socket should be attached to a Blue wire as you note. This wire should then run back to the D+ terminal of the voltage regulator. There is also a Blue/Green wire attached to this terminal. Without the engine running both of these wires should ground through the regulator to illuminate the Alt and OXS (Blue/Green wire) lights as the initial test indication for the bulbs. You can disconnect the Blue/Green wire and it should not affect the alternator’s ability to charge (you may want to unplug to isolate the charging system from the OXS system for troubleshooting).
2. The alternator needs to have the field excited to begin charging. This is accomplished through the power supplied by the Red/Black wire through the indicator bulb then through the Blue wire to the voltage regulator. If the indicator light does not illuminate with the key turned to run and the engine not started, there is a problem in the system.
A. Check for 12V on the Red/Black.
B. Check continuity through bulb socket and bulb, test bulb.
C. Check continuity to ground via blue (at bulb socket connector) wire through voltage regulator.
If “C” fails, remove blue wire at regulator and ground to engine to see if Alt Indicator light illuminates. (May want to have a fuse inline when you ground just in case there is an issue so you protect your wire harness)
3. I think the bulb socket is part number 999.632.007.00
Let me know what you find and I'll see if I can help further.
Good luck,