Battery idiot light
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Junior User
Joined: Apr 2005
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Battery idiot light
What is the instrument cluster monitoring for the battery idiot light on the dashboard, my truck's battery light was intermittently flashing, now constant on, alternator output is 14.1V and regulated. Battery is fine, volt gauge even shows proper system voltage? Can anyone help with this one?
Thanks
Brian
Thanks
Brian
Lead Driver
Joined: Sep 2002
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From: Gateway to the West
The battery light is an indicator that the battery is no longer receiving a charge from the alternator. If the system is wokring properly, the (idiot) lamp circuit may have developed a short somewhere. The voltage regulator in the alternator should be the control device for the battery idiot light. In other words when the output voltage of the alternator drops below a certian point, the light is turned on. Thats why it comes on when the engine dies and before you start the truck. Alternator output is less than battery output.
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I was almost sure thats what it was, a comparison of alternator output to battery voltage, or to a refernce standard (12.5v or so), but in this case I can guarantee you it is a malfunctioning circuit, my question is how does the circuit actually work, I can tell you for sure the alternator's regulator does not have a "idiot light output line", somewhere else it is being figured out. I am not sure if the ECU is looking at its input voltage and then outputting the signal to the light, the only thing that has been disturbed recently is C202 (76 pin firewall connector), the high current one, not the ECU one. just for good measure yesterday, I disconnected it and put a load of silicone dieelectric grease in it, and reconnected it, idiot light still persists. I am not so worried about the light as much as I am what else is affected (low ecu voltage, etc). This poor thing is falling apart lately.
Thanks
Brian
Thanks
Brian
