1998 V70 Died while driving - won't start, no spark

[abscate]

Nicely sleuthed. That's a lot of bad wiring! If you can get the wires apart in the loom I would just electrical tape them, with 3M stuff, not the generic

[kjhiggins]

Thanks. The harness is out of the car so I can definitely tape them and I'll check the rest of the wiring for this sort of problem. When I get it back in the car I'll try to figure out why exactly the insulation wore off and if it corresponds to one of the cable ties.

[abscate]

I'm looking closely at those pix. That does not look like chafing, that's melting and burning of those wires. Something is shorting multiple circuits in that loom, I think.

I would pull a wiring diagram and identify these wires by colour and look for a common fail point

[kjhiggins]

Sorry for the long delay in replying - busy at work and traveling so haven't had enough time to work on this lately. Looking at the wires themselves you can see other places where the insulation is wearing through so I think they look the way they do in the picture due to shorting after the chafing wore through the insulation.

The wires with the worst insulation damage correspond to:
1. Orange/gray stripe -- control signal injector 2
2. Blue/white and blue/black twisted pair -- IAC opening signal/closing signal, respectively
3. Green/gray and green/black twisted pair -- signal (-) front HO2S/signal (+) front HO2S, respectively
4. Blue and red/black twisted pair -- signal ground RPM sensor/signal RPM sensor, respectively

Given this information, I'm going to look at the fried ECU's to see if I can determine any damage in the corresponding circuits.

[kjhiggins]

I went ahead and repaired my harness with electrical tape where the wire was still good and cutting and soldering where the wires had actually started to break, using marine heat-shrink tubing on those so they'd be water-tight. I went inch-by-inch along each wire, even removing the split plastic protective covering on all the branches, and found several more places where the insulation had worn through. I also popped the plastic cover off the rest of the engine compartment harness (the part that wraps around the driver's side and ends up going through the firewall) and found it quite grimy so I cleaned it but there was no damage to the wires. I put yet another ECU in it and got it back on the road two days ago for a few miles and then more yesterday and today. All seems well (holding my breath!) It's up to 60 miles, which is 49 miles further than it went the last time I replaced the ECU. I'll give an update in a month, or if it stops again.