2004 Volvo s60 Unusual electrical issue causing car to die

[volvonator1]

I own a 2004 volvo s60 2.5t awd, I purchased this vehicle at an auction about 6 months ago, It had an warning on the dash saying "SRS Airbag Service Urgent"But it didnt effect the car and i got it saftied with it. After driving the car for about a month i had no issues with it and it was driving good. I don't drive too far because my work is in town and so is my school so im normally just driving it across town . I went snowboarding one day and after driving on the highway for about 45 minutes, I felt a little jolt as if i ran over something really small and the lights flickered then the red warning light came on in the middle of my dash after driving for another 15 minutes all my electrical shut off(Lights, Abs/anti skid, all my gauges are at 0, etc) and my engine continued to run so i pulled off and parked. After waiting 30 minutes my car started backup and continued to drive fine for the rest of the night. Now everytime I drive too long on the highway or even in town my car will do those same sequence of events, And i just pull over and wait then my car is fine again. I thought something may be overheating like the ECM but i dont know exactly.




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[coflynn]

There's a lot of evidence pointing to ECM overheating causing such issues. See in particular this thread: https://www.matthewsvolvosite.com/forums ... 1&start=14 and check out the last page, there is photos of a heatsink install on the ECM. You can also confirm it's getting proper cooling etc (I think there is a fan or at least vent that could be blocked) before doing such a mod.