voltage drop after pothole incident
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Instructor
Joined: May 2015
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voltage drop after pothole incident
Hello guru's! I need some advice. I hit a pothole pretty hard last night with the passenger side front tire. After that my voltage started dropping till it got to 10. I couldn't restart without a jump. Battery is 12.7 volts disconnected and 12.7 connected. Yet the dash shows 10 volts. You jump start it and the gauge starts dropping till dash shuts down at 8 volts. The alternator is putting out 14 volts and the battery is really at 8 volts when running. I have a feeling I messed up my starter solenoid when I smacked that pothole.
Tech Contributor
Joined: Dec 1999
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From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
The IPC digital voltage readout and the IPC Analog meter DOES NOT read TRUE battery voltage.
It reads the voltage output of the IGNTION SWITCH for the HOT IN RUN and START circuits.
I recommend that you examine the ignition switch for proper battery voltage output.
Each module that has multiple battery voltage inputs uses direct battery buss input and IGNITION SWITCH (ON) input.
If the ignition switch ON/RUN voltage is low,, that is the issue you are seeing.
Bill
It reads the voltage output of the IGNTION SWITCH for the HOT IN RUN and START circuits.
I recommend that you examine the ignition switch for proper battery voltage output.
Each module that has multiple battery voltage inputs uses direct battery buss input and IGNITION SWITCH (ON) input.
If the ignition switch ON/RUN voltage is low,, that is the issue you are seeing.
Bill
Race Director
Joined: Apr 2007
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From: South Western Ontario
In a few of the service manual documents I've been looking at, they show the voltage gauge is using serial data from the PCM. It is likely still the ignition switched voltage but it didn't appear the gauge read the voltage directly.
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
Yes, if the alternator voltage is 14V while the battery voltage is 8V, then there is no connection between the alternator and the battery. Examine the wire from the alternator to the solenoid, the fusible link at the solenoid and the connection at the main solenoid post for damage.
In a few of the service manual documents I've been looking at, they show the voltage gauge is using serial data from the PCM. It is likely still the ignition switched voltage but it didn't appear the gauge read the voltage directly.
In a few of the service manual documents I've been looking at, they show the voltage gauge is using serial data from the PCM. It is likely still the ignition switched voltage but it didn't appear the gauge read the voltage directly.
Where are you reading or observing BATTERY VOLTAGE from? The IPC gages or directly on the battery terminals.
IPC FUSE 18 Is the HOT IN ON & START feed (from the Ignition Switch ) that powers the IPC Analog & Digital meters. -
Thread Starter
Instructor
Joined: May 2015
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I fixed it! The leads on the starter solenoid were loose and corroded. The jar from the pothole was the final straw since I found that the nut was only hand tight. I had ohmed out the lead from the battery positive terminal to the alternator and it showed open. After cleaning and tightening the leads i got .3 ohms. The voltmeter now reads a steady 13.8 with the engine running. Thanks for the help everyone.
