Losing engine gauges, speedo, and fan staying on

[Mrkentee]

Driving along and lost gauges, and fan came on and stays on.
Took abs fuses out and ran fine. Thought I had it figured out until I got home.
Started doing it again. Put jpro on and confirmed abs faults.
Disconnected every abs and removed fuses. No help.
It comes back for a while if you’ve been sitting, and is slightly sporadic.
When happening get low voltage at diag plug.
When working voltage and resistance are perfect.
I’ve checked everything I can think of. All the wiring I can get to.
I’ve had some codes on my elog for bad intelligent device, and abs, and cab controller.
The elog is affected by the low voltage at the ecm plug, so it’s probably not the cab controller. That’s also why my inline 5 wouldn’t connect.
I can drive it, but no gauges and the fan stays on.
I’m wondering if it might be the ecm, but the engine runs fine.
2010 Peterbilt 386