2002 Thomas FE coach, died on the highway, hotwire it to get it going

[Krazyistkarl]

The issue for me right now, is that because i used the bus to move to BC, it is also currently my daily driver, so tearing the dash apart is a big deal and I'll do that as a last resort.

In the mean time, I hooked up the "jumper" to a heavy duty toggle in my switch panel, so I can jumper the coil from inside now. While doing so, i discovered that if the purple/white signal wire is disconnected from the coil, the ignition wont start the bus, even with the coil jumpered.

I'll try and upload some photos today

[Iceni John]

When you've sorted out this problem (and it probably won't be the last such head-scratcher you'll ever have!) I strongly recommend that you go through your entire chassis electrical system from top to bottom. Replace all the solenoids and relays, even if you think they're working OK for now. Check the resistance of every ground connection, and if they don't ohm out correctly then make new grounds. If you're not sure about the heavy high-current cables, peel back some of their heatshrink and check for corrosion; if there's green stuff growing there, cut back the cable to fresh strands and crimp on new lugs, or just replace the cables entirely. Ziptie every loose wiring bundle or wire so they cannot move at all and are well clear of hot or moving things. Apply contact cleaner to every push-on connection and slide them on and off a few times to clean them. Unscrew all nutted connections with ring terminals and lightly sand every terminal clean, then use stainless washers and nuts to resecure them.

Sure, it's work to do this, but being stuck with a dead bus on the side of the road isn't fun either. And get the factory electrical schematics! Once you get your bus back onto a diligent PM schedule it will be reliable, but for now you're catching up on years of deferred maintenance and slapdash repairs.

Good luck, John