A couple of nights ago, I noticed my headlights were bright, then dim, then bright and then dim and so on. Eventually my battery light came on, then turned off, then back on...
I plugged in my OBD2 Bluetooth ELM adapter, checked on my phone, and it showed that the voltage going to the ECU was only 12.6, then when my headlights would get normal bright again, the ECU was getting anywhere between 13.6 and 14.2.
Alright, it's probably the alternator (most likely only the voltage regulator), I'm only at 80K, but it can fail. So I swapped it today.
Started up the truck, battery light was on, and I have the same problem. Scan tool shows voltages between 11.9 and 12.8, occasionally it would jump back up to 14.0, all while sitting in the driveway idling.
If the engine is running, the alternator should ALWAYS be putting out anywhere between 13.8 and 14.4, right?
I was getting tires a few weeks ago, so I asked them to check the battery and alternator, tested OK, but this was before I started seeing the battery light.
Anyone have any ideas of what might be going on?