Charging system problem
#16
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I went straight from the gauge to the alternator blue wire. A bit of a PITA, and as I stated, this should only be a temp fix to get it going.
Once again, this is only if:
A. The bulb check does not light when the ignition is turned on.
And:
B. The bulb itself is still good. A bad bulb would merely have to be replaced to fix this issue.
I simply used my multi meter to figure out which wire it was at the cluster plug, then cut it and ran it out to the alternator and connected it to the alternator's blue wire.
Once again, this is only if:
A. The bulb check does not light when the ignition is turned on.
And:
B. The bulb itself is still good. A bad bulb would merely have to be replaced to fix this issue.
I simply used my multi meter to figure out which wire it was at the cluster plug, then cut it and ran it out to the alternator and connected it to the alternator's blue wire.
#17
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Do you remember which pin you took it from the instrument cluster? Pin 3 connects to the ignition switch and the coil. Pin 4 leads to the alarm module and so does the blue wire from the alternator.
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I jumpered between pin 4 and the blue wire and it is still only at 12V. I have confirmed the bulb is good and the connection between the bulb and the coil is good.
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Ok after a full day of checking just about every voltage I can find I come up with this:
D+ - B+ Off->12.3VDC On .889VDC Running .824VDC
blue to ground Off .1mV On 11.2V Running 11.3V
I have the wiring diagram and I have an understanding of how the circuit works but it is a differential circuit and it is really confusing me. I don't know what the regulator circuit looks like so I am having a hard time telling if it is that or the diodes in the alternator.
You know the really sad part is that I am an Electronics Technician 2nd class in the Navy but it has been years since I have had to troubleshoot a circuit. I am a net admin type.
D+ - B+ Off->12.3VDC On .889VDC Running .824VDC
blue to ground Off .1mV On 11.2V Running 11.3V
I have the wiring diagram and I have an understanding of how the circuit works but it is a differential circuit and it is really confusing me. I don't know what the regulator circuit looks like so I am having a hard time telling if it is that or the diodes in the alternator.
You know the really sad part is that I am an Electronics Technician 2nd class in the Navy but it has been years since I have had to troubleshoot a circuit. I am a net admin type.
#21
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If you have the back cover to the alternator off, the only reading you need is to, with the engine running, connect the positive lead of the voltmeter to B+, which is the alternator output, and the negative lead to the alternator case (ground). If the voltage is anything less than 13 your alternator is not working, either rebuild it or replace it, simple as that.
Also, as a side note, voltage drop tests are only valid if the circuit in question is active like Chris Prack said, in the case of checking the charging circuit that would mean engine running.
Also, as a side note, voltage drop tests are only valid if the circuit in question is active like Chris Prack said, in the case of checking the charging circuit that would mean engine running.
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Drove to work this AM and after the car had warmed up and I turned the lights on and reved the engine I got just under 14V on the voltmeter. Unfortunately I did not bring my multimeter with me. I will just take the alternator out tomorrow and have it tested.
I think she knows I am about to get my 914 running again and she is having a tantrum.
I think she knows I am about to get my 914 running again and she is having a tantrum.
#24
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IIRC, it's the bulb's ground wire that ultimately connects to the alternator blue wire. The bulb lights up by using the alternator core as it's ground, and this energizes the alternator. Once energized the blue wire on the alternator no longer reads ground, and this shuts off the bulb.
#25
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5mV at the same test points as above. I just checked the owners manual and it says the light on the voltmeter is an alternator warning light. It should come on when I start the car then shut off when the engine is running. It does not light at all now. The master warning lights when I star but then goes out when the car is running. I have started the car about 5 times now and the battery seems to be holding ok instead of running down. Is there some circuit that tells the alternator to start charging depending on engine speed? I am perplexed.
The "idiot" light should come on key on engine off. If the bulb does not light you have a problem. The light bulb acts as an exciter for the charging circuit. Key on, engine off the bulb has power on one side and the alternator is providing ground on the other to light the lamp. Once the alternatror starts turning the power side of the bulb fields the alternator and both wires have power tuning off the light.
When you rev the engine over 3k rpm you are force fielding the circuit and it starts to charge. What I would do is remove the regulator and take a close look at the brushes. I bet you will find they are either worn down and are two short or they are worn unevenly. Either way you will need to replace the regulator.
You should be able to get one pretty cheap.
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Just wanted to update with the solution.
I removed the alternator and had it checked at Autozone and it showed good. I figured I would replace the voltage regulator anyway and when I took the old one out the brushes were worn down to nubs. I put the new regulator in and reinstalled the alternator and now I get a solid 14.5VDC.
Thanks to all for the help.
I removed the alternator and had it checked at Autozone and it showed good. I figured I would replace the voltage regulator anyway and when I took the old one out the brushes were worn down to nubs. I put the new regulator in and reinstalled the alternator and now I get a solid 14.5VDC.
Thanks to all for the help.
#27
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Just wanted to update with the solution.
I removed the alternator and had it checked at Autozone and it showed good. I figured I would replace the voltage regulator anyway and when I took the old one out the brushes were worn down to nubs. I put the new regulator in and reinstalled the alternator and now I get a solid 14.5VDC.
Thanks to all for the help.
I removed the alternator and had it checked at Autozone and it showed good. I figured I would replace the voltage regulator anyway and when I took the old one out the brushes were worn down to nubs. I put the new regulator in and reinstalled the alternator and now I get a solid 14.5VDC.
Thanks to all for the help.
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