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Discussion Starter · #1 ·
Anyone else get a voltage drop intermittently under load?

I will be at speed and have 13.7-14v, then it will drop down to 12.8 for a second before returning to normal. Happens randomly with headlights and radio on and/or off. I can hear the cabin fan speed change with the change in voltage. Voltage checked at obd with Torque.

Cabin fan sometimes will shut off randomly in position 3, but I figured it's just a resistor pack and not related. Did a few engine grounds about a year ago, and I don't see a change at idle. 20 month old battery.
 

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My alternator acted like that 6 or 7 years ago. My indication was the side lights would get brighter then darker when backing out of the garage in the early morning. I suspect that the alternator was charging, then not charging due to worn brushes. Two weeks later, it failed 60 miles from home, Luckily, the battery alone got me home after I shut off all non-essential equipment in the cabin... Ron
 

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Discussion Starter · #4 ·
Check the belt and tensioner - it may be slipping intermittently.
The tensioner pulley seized maybe 6mo ago, so that and the belt are recent. Water pump went last month and had a ton of play in it for about 80 miles til I replaced it. Top of motor is quiet, I'll get under it while running and listen.

My alternator acted like that 6 or 7 years ago. My indication was the side lights would get brighter then darker when backing out of the garage in the early morning. I suspect that the alternator was charging, then not charging due to worn brushes. Two weeks later, it failed 60 miles from home, Luckily, the battery alone got me home after I shut off all non-essential equipment in the cabin... Ron
If it is the alternator, any recommendations?


Over an hour in the car today and didn't notice a voltage drop. Outside temperature did drop a few degrees.
 

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I had something similar, but it would fluctuate between normal voltage and higher than normal (you could still see a difference in light intensity tho). Changing just the voltage regulator in the alternator fixed it, the brushes are contained in the voltage regulator, so like Ron states that could be the cause.
 

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you mean, when you punch the turbo? I get the battery warning sign when going hard usually from a slow speed to a five second boot on the throttle it might come on. likely is the blow by oil I have all over the motor's **** currently.
 

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Oil on serpentine belt creating slipping perhaps .
In the thread above it was most likely the voltage pack in the alternator failing , and not directly related to Acceleration,
EG Ron mentions backing out of garage, I can only assume that isnt under full Boost ...................

Battery lights flickering on is suggesting either a slipping belt or a failing voltage pack . Sort it at your convenience because if it is a voltage pack that can leave you up some sort of creek , paddleless.
 

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I know this is unlikely - but could it be a connection to certain fuses or relays also causing some grief?
We know some specific relays are prone to acting up - eg the orange lamp control relay.
 

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is there a full moon somewhere, we seem to have a rash of people responding to multi year old threads.
 
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That happens. multi-year treads for a multi saab guy eh?
 
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