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rhett rhett is offline
Frankly my dear....
 
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Join Date: Jan 2010
Location: England
Posts: 517
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Quote:
Originally Posted by bell View Post
Yes the bulb is required for the alternator to start it's charging state.....
also.....on 944s (late only iirc)) the alarm brain is in the passenger footwell, that circuit loops through it......
On cars without an alarm it still has the alarm harness which has a jumper plug in place of it.....
I have seen numerous people remove their alarms then have a no charge situation for this reason.
I have also done many conversions with gauges etc....and without that little bulb working the alternator will not charge.

Also the light and volt gauge run off of 2 different circuits...
Yep, looked at the CCT diags and Bell is spot on..for some reason Porsche looped the blue wire OP from the alternator through the alarm...or a jumper if not fitted, so there is a possible area for investigation.

However, there is also one more component that might be faulty, the 68R 5W resistor that shunts the bulb. If the bulb has gone and the resistor is faulty then the required voltage will not be present at the alternator. Might be an idea to check that CCT too. 68R across the resistor with no bulb...probably about 10R (ish) when a good bulb is in circuit.
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Old 03-26-2013, 02:51 PM
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