This is not a skoolie question per se but I was hoping someone here might have some answers for me on this.
I moonlight as a party bus chauffeur for a tiny limo company in a small college town. I was hired because he has another bus and another driver already but he is getting popular and needed to add another bus (before you ask, yes he is legit for hire, buses are registered and insured as CMVs with USDOT#, and we have CDL-P's). So basically he went cheap and dirty on the second bus, he said he spent about $1500 on it. He did up the interior nicely, and during the off season we will be doing some more upgrades as well. But like most old buses that have changed hands a few times, it now has hacked up wiring and a few gremlins in the electrical system. I'm good with electrical, and I have this whole 3 day weekend off with nothing to do except be bored, so I've taken on trying to straighten it out, versus him spending a lot of money for a shop to do it.
So anyway.. This is a Terra Transit "Turtle Top" bus built on a 2003 E450 cutaway chassis. The driver's control panel has intermittent times where it just quits (the passenger lights go out and the door won't open/close). I've tried hitting the switch panel but it does not affect it. It DOES come back when I tap on the relay board itself though. Thusfar I have not been able to induce a failure by tapping on it though.
While trying to decipher the add-on spaghetti, I managed to lose all power to the relay board though. It has battery feed, but the IGN feed is dead. There was fused line coming from the IGN terminal on the board (fed the rear HVAC blower switch), which also had a T-tap on it. When I traced that out, I found it was T-tapped into another IGN feed that originally fed a 2-way radio.. So basically at some point the IGN feed from the cutaway harness (labeled #2 IGN/ACY POS) died, and they just hotwired it from another circuit. Genius.
So this brings me to my real question.. Is there a diagram available which shows circuits in the cutaway harness and where they are fed from? I have tested all of the fuses under the dash and they are good. I don't know if there is another fuse box somewhere else (besides the PDC under the hood), or if maybe there is a fuse missing (there are a few unpopulated slots)
I also need to find out little things like why the roof hatch alarm does not work, why the red lights over the emergency exits don't work, etc. The lower power port ( the one I believe is supposed to be switched with the ignition) also does not work, and I am wondering if it is the same circuit as the IGN feed to the relay board.
So does anyone have any insight? I'd really appreciate any help you can point me to.
Here's some pics..
HVAC control relays
Lift interlock (this board has an issue too, probably a cold solder joint on the terminal strip because it cuts in and out when I press on it - and all screws are tight)
Main relay board (door control board is below this, those two relays at the bottom)