New to this site and looking for help

[Pstone-SKO]

Hi, I am new to this site and am new to a forum site. I am learning my way around. My church owns a 2001 E450 V10 Champion that I drive frequently. Someone had lowered the handicap lift in it and then said it stopped working and they pushed it back in place slammed the doors and fastened the lift back in place with a seatbelt. Needless to say I was very sad. They said it just quit working. I took a look in the fuse box just above the drivers seat and found 2 blown fuses and a wire connector that had been melted. So I replaced the blown fuses, one was an in line 20 and the other was a 30 that was on the fuse block that was next to the melted connector. I replaced the connector as well and then started the van. The connected got real hot again so I turned the van off. The wires went to the rear heater relays. My question is should the connector get so hot that it melts the insulation on the connector and what would cause it to do that? Sorry for the long story.

 

[Dapplecreek]

...should the connector get so hot that it melts the insulation on the connector and what would cause it to do that?

No, it should not do that.

Heat in an electrical circuit comes from electricity running through a resistance. The connector doesn't QUITE conduct electricity as easily as wire does (that is, it provides some resistance) so it gets hot first. Think 'doorway' as a crowd is trying to push through it.

Normally the amount of electricity running through the connector is waaaay below what would cause it to heat up like that, so that means that it is getting waaaay too much electrical 'traffic' that it is designed for. That's likely (well, almost certainly) because there's a short circuit at the other end.

A short circuit is where the wires that supply electricity to the motor (or light, etc.) at the other end are touching each other or the body of the bus. That way the electricity has a shorter way to get back to the battery/alternator. So much electricity goes through the wires that one can easily start a fire or melt the insulation off the wires from one end to the other.

Fuses are SUPPOSED to melt before the wires do. Most of the time they do (though I lost the wiring harness on a car once when it didn't). In your case, finding melted fuses should have prompted a bit more looking for rubbed wires or the like before firing it up. But - hopefully you shut things down before melting the insulation.

For testing, I would suggest buying a cheap ohmmeter or multimeter. Harbor Freight gives 'em away with coupons, or sells 'em for eight bucks or so. Use the 100k resistance setting, and look at the dial. It will show infinite resistance. Touch the test leads together and you'll see the resistance drop to zero (indicating a short). LABEL and then disconnect everything at the lift, and put electrical tape over any exposed wires that you disconnected. Pull those fuses so those wires are disconnected from anything at the front of the bus. At the fuse end, find the wires (or the connector for the fuse) and use your meter to check the resistance between each wire and ground (the unpainted metal of the bus body). Then check resistance between each wire and the next. If all is well, you OUGHT to have infinite resistance everywhere, showing that each wire is on it's own and not electrically connected to any other wires or the body of the bus.

If you see low resistance between any two wires, you may have burnt the insulation along the line somewhere. Might need to replace the wire, front to back. If you see low resistance between a wire and ground, look for places the wire might have worn against the body and damaged the insulation. If you find a place where the insulation is rubbed bare, use electrical tape to insulate it and see if you can reroute the wire or put some sort of cushion there to prevent the same thing from happening again.

If all of the wires show infinite resistance between each other and between the wire and ground, I would fire up the bus and see if things got hot. If the don't, the problem was in the lift motor or a switch or something at the far end - after where you disconnected things. Can't help you much there.

Hope this helps.

Disclaimer: I read a lot and have done some electrical work in my time. And I taught high school science. But this is a tinkerer giving an opinion, rather than an expert electrician talkin'.

 

[cowlitzcoach]

One of the problems with all van/cut-away buses is the marriage between the chassis and bus body is never a happy marriage and usually ends in an ugly separation.

Wiring issues are not uncommon.

If your lift has a switch on the dash or switch panel that turns on and off the power to the lift, that switch is only turning on a relay. The power to the lift uses a wire the size of a battery cable and in some cases might even be bigger than the battery cable on the bus. That circuit shouldn't have a very large fuse at all since it uses the relay to carry the large load. Somewhere between the battery and the lift motor there should be a fuse or circuit breaker that protects that circuit. I would lean more towards a circuit breaker than a fuse.

A 20-amp circuit or a 30-amp circuit would seem to be more the size of a circuit that would send power to a set of heater blower fans.

Before you go any further you need to determine which circuit the 20-amp circuit is serving and which circuit the 30-amp circuit is serving.

IIRC, above the driver either on the driver side of the bus or in the front panel there should be a printed copy of the wiring diagram for your bus. It will most likely not be very legible. If you can't read it you should be able to contact your nearest dealer and ask for a new copy. You will need to supply the dealer the VIN. You may or may not be able to get a new copy. Most of those buses were built pretty much the same so you might get lucky.

Don't continue to let the wires get hot. You run the real risk of burning your bus to the ground.

The key switch should be turning on a relay that sends power to the bus switch panel. That circuit is most likely protected by a circuit breaker.

From the switch panel you will have circuits going to all of the accessories. Somehow, if you don't have a wiring diagram, you are going to have to find which circuit is which. Once you determine which circuit is getting hot you will have a better idea as to where you will need to look to find where the wire has been crushed or rubbed raw to create a dead short.

Good luck and keep us posted as to your progress.

 

[Stu & Filo. T]

Few yrs ago I when I had my Class C & I bought my house I had to park it in my front yard while I did work on the house before moving in, It was August & 100 deg plus days & I had the RV plugged in with a 100ft extension cord on a reel with the AC running full blast. Well I walked outside & heard the AC surging & then walked into the garage & there was the cord & reel melting into a pile of goo.