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LOW Voltage

Old Oct 30, 2024 | 04:03 PM
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Default LOW Voltage

C5 2002 ..... Low voltage light comes on after 3 minutes running. Gauges go out. New battery and alternator checked OK. Stops running after 10 mins. ANY IDEAS, PLEASE.
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Old Oct 30, 2024 | 06:16 PM
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The voltage circuit that the IPC uses for the voltmeter and the low voltage warning comes from the Ignition 1 circuit and fed through fuse 19 (IP Fuseblock)…do a voltage drop check by placing one lead of your voltmeter on battery positive and the other lead on either of the test points on top of the fuse…you should only see a 0.2 to 0.3 voltage drop…that circuit is fed through the ignition switch and feeds some important things like the fuel pump and PCM…do you mean the car shuts off after 10 minutes ??…this may be a bad ignition switch…it may be easier to do the voltage drop check from battery positive to the fuel pump fuse 13 in the under hood fuse block…that way you don’t have to run your leads from the battery all the way to the IP Fuseblock.

Last edited by C5 Diag; Oct 30, 2024 at 06:45 PM.
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Old Oct 31, 2024 | 02:11 PM
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Originally Posted by C5 Diag
The voltage circuit that the IPC uses for the voltmeter and the low voltage warning comes from the Ignition 1 circuit and fed through fuse 19 (IP Fuseblock)…do a voltage drop check by placing one lead of your voltmeter on battery positive and the other lead on either of the test points on top of the fuse…you should only see a 0.2 to 0.3 voltage drop…that circuit is fed through the ignition switch and feeds some important things like the fuel pump and PCM…do you mean the car shuts off after 10 minutes ??…this may be a bad ignition switch…it may be easier to do the voltage drop check from battery positive to the fuel pump fuse 13 in the under hood fuse block…that way you don’t have to run your leads from the battery all the way to the IP Fuseblock.
Thank you so much. Very detailed!
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Old Nov 2, 2024 | 07:30 PM
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Default Voltage drop

Originally Posted by K. K. Floeter
Thank you so much. Very detailed!
The positive output wire from the Alternator to the Battery goes on a detour to the starter before reaching the battery. Because of the high temp, the terminal on the starter develops high resistance causing reduced voltage to the battery. You have to remove the wire off the starter and clean the terminal and wire. You have to get to new clean metal on the eyelet. This usually fixes this problem. On my c5, I also ran an auxiliary 6 guage wire from the Alternator around the back of the engine to the pos battery terminal, with a 250 amp fuse link in series. Also covered wire with the corrugated plastic covering to protect it. Anyway, to test you can do a voltage drop between the alt. Pos and the Pos bat post with a voltmeter in parallel. Hope this helps. Good luck
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Old Nov 2, 2024 | 11:21 PM
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Make sure the battery cables are TIGHT.
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