I had XeModeX rebuild my Magnelli ETM over a decade and 100k miles ago. I recently starting having symptoms of a similar failure - rough idle. ETM test showed very intermittent dithering. I suspected wiring and, through various checks, eventually had bypassed all original wiring w/ temporary jumper ...

Removed ECM and cleaned both harness and module -side connectors w/ QD Contact Cleaner. No signs of corrosion, loose pins.
Disassembled ECM and cleaned PCB.
Conformal coated PCB w/ 3x light passes of silicone (200*C MG Chemicals 422B-340G spray).
Laid a bead of RTV (Permatex, grey IIRC) along ...

No PEM on my '01.

I disassembled and cleaned the ECM chiller box, ensuring no evidence of water intrusion or air infiltration. Confirmed that cab air comes in the box from the back. Confirmed no corrosion on ECM pins, and no evidence of damaged or corroded pins. The original insulation on the ...

@br0dy519: I installed a new Bosch starter (3) months ago, while also shielding the starter wire w/ foil-lined sheathing similar to this . Neither improved the issue. But I'll look into it more - may be entirely reroute the starter cable.

Problem continues intermittently. Since last update I found ...

Damn, you're right. I just found it. I looked a few years ago and didn't have any luck, but lo-and-behold:
https://usparts.volvocars.com/a/Volvo_2 ... 75950.html

I found about (3) sensors with similar wire damage near the sensor, showing exposed wires. In 1 of these cases, the wire was twisted in a way that might have allowed them to short together intermittently. In all (3) of these, the damage was right at the connector - unable to repair without replacing ...

I drive my car very rarely - typically takes me 2 months to go through a tank of gas. The failure came back yesterday. I will keep digging into some of the further reaches of the harness, that I haven't yet unloomed & inspected. Will update w/ findings.

Discovered the PTC heater wiring leads have exposed wires & corrosion right at the connector. You can better see this in the photo after I cut the connector off the main harness. I suspect this was causing a short, and shares a common ground w/ the ETM, and common power to the TCV. Since the ...

In order to pass emissions, I've been driving the car every day for a week to get it to go show OBD Readiness. No failure recurrence.
Last night it finally showed "Ready". When I started the car this morning, the failure recurred. I left the key in Pos2, and after ~10s (as always) the failure ...

Signal wire at alternator checked fine. Battery at idle shows 13.5-14VDC.

While investigating wire harness for any potential shorts, I discovered the VVT solenoid wires had cracked and were intermittently shorting! Digging further, found significant damage across all the ignition wiring back to the ...