Windows, radio, and gauges acting spooky is rarely a haunted PCM — it is usually power, ground, or network.

What it usually proves to be (in order)

1. 1A weak battery or bad ground making modules brown-out and log phantom U-codes
2. 2Corroded connectors or pin-drag in a power distribution point
3. 3A CAN-bus wiring fault — one bad twisted pair disables a whole network section
4. 4A genuinely failed module — always the LAST thing on the list, never the first

What a parts-changer will tell you

PCM failure ($1,200–$2,000 reprogrammed) — the scarcest part on the invoice but the easiest one to blame when nobody checked voltage-under-load or the bus waveform.

Typical guess-and-swap cost: $1,200–$2,000 (module swap) when a $180 battery or $40 connector repair was the fault

The test that proves it

Battery/charging load test first, then voltage-drop testing on power and ground circuits under load, then a CAN waveform check at the modules. The network almost always confesses.