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S Chassis Technical discussion related to the S Chassis such as the S12, S13, S14, and S15. |
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07-24-2019, 01:10 PM | #1 |
Removed dash now alternator not working?
I was removing my dash to replace a couple Ac blend door actuators, all went well got them working. But before putting the dash back on I wanted to keep the car running while switching them back and forth between vents. Testing it before putting the dash back on basically but the car stalled soon after and battery was dead wouldn’t start it back up. Placed battery on a charger, came back at it later when it was fully charged. All good starts up fine so I checked voltage. Reading 11.98v w/ the car running, 12.6v with the car off, so battery is good. Check the voltage off the alternator and nothing, it’s reading the 11.98v when the car is running. My assumption was that I had my alternator gave out. (Ka24de w/Quest alt) , so I go into my parts bin grab a known working alt. (Downgraded back to stock w/ bracket) installed, but still not charging. Went to autozone got the quest alt tested and it was fine. So alternator doesn’t seem to be the issue? I’m leading towards the plug next, am I suppose to see constant voltage at 1 of the 2 pins or what? Etc? That’s the info I’m here to ask for, what’s next for me to check. (Note: I did check alternator fuse, even switched it with another one seems fine. Also took a look at all the other fuses. Also my cluster is plugged in, at first it wasn’t when it first died on me but problem still there. )
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07-24-2019, 04:48 PM | #2 |
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Is the charge warning lamp on the gauge cluster staying on when the car is running? Does it light at all?
The back side of the gauge cluster has uninsulated solder joints. They can short out against the vehicle frame if you're moving the cluster around with ignition turned on. Those circuits are mostly protected by a small fuse (7.5amp on an S14). What model vehicle are you working on? |
07-24-2019, 10:25 PM | #3 | |
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07-25-2019, 11:16 AM | #4 | |
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07-26-2019, 08:04 PM | #6 |
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The charge indicator bulb is powered by an underdash fusebox fuse. The bulb is grounded by the alternator.
Disconnect the alternator 4-pin connector. Turn ignition key on; engine not running. Voltage test pin 3 of the connector. It is a white/red wire according to my '95 service manual. You should get battery voltage. If you have no voltage; check for open wiring from fuse to bulb to alternator. Check for a blown bulb in the charge warning lamp gauge. If you have battery voltage, check for a faulty alternator ground wire. Normally you can bypass the charge warning circuit by simply revving the engine up above 2500rpm. This will be sufficient to energize the alternator field coil and the alternator should continue to charge until the engine is shut down. |
07-26-2019, 08:08 PM | #7 |
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Oops. It's not a 4-pin connector. It's a 2-pin. White/red wire is the one you want.
The three wires (other than the fourth ground wire) should all have battery voltage when the ignition is turned on. |
08-02-2019, 08:41 AM | #8 | |
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08-02-2019, 09:08 AM | #9 |
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12v is low. alternator should be outputting close to 14v.
when you had the alternator tested was it able to output 14v under load? |
08-02-2019, 03:05 PM | #10 |
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Your voltage checks are all normal. This leaves you with a faulty alternator or ground.
The alternator is responsible for grounding the bulb circuit. You can do a quick bulb test by bypassing the alt. Disconnect the two pin connector from the alt and use a short piece of wire to hotwire the white/red wire straight to chassis ground. The charge warning bulb should illuminate nice and bright whenever the key is turned ON. Test the alt ground wire or temporarily replace it. If an alternator has extremely underdriven pulleys on it; it won't spin fast enough to charge at idle. |
08-02-2019, 03:11 PM | #12 |
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ah gotcha. with engine off 12v is def normal.
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