Back up lights

[Moose]

As I am trying to finish up and get my bus on the road. But my backup lights and back up alarm are not working. Any help appreciated.

[PigPen]

Have you checked fuses?

[Moose]

no I haven't . I will have to pull and check each one I guess. No info on fuses available here

[PigPen]

Were they working before and just stopped or have they not been working for a while?

If it were me, I'd at least start with checking connections and fuses. It sounds like you don't know which fuses you need to check. Do you have a multimeter? If you do, most fuses can be checked without actually pulling them by using the exposed metal on top (holes in plastic) to check for continuity.

[tlbeck1985]

Also, any idea if they went out at the same time?

[Moose]

Don't know if they were ever working. I replace the old backup alarm and when I it did not work I checked circuit and found no backup lights

[tlbeck1985]

I'd test for voltage at the backup alarm. Use two different grounding sources, like the - wire and then the bus frame. If you don't have voltage I'd agree that it's most likely a fuse. It could possibly be that a couple wires in a bundle got cut somehow, which could also cause a short and blow the fuse. I'd start by tracing the + back and looking it over as best you can. If you put a new fuse in and it pops again, it's knicked, which means you gotta find and repair it.

If you have voltage at the alarm using the frame as a ground, it's a bad ground wire.

[Robin97396]

My backup alarm was disconnected when I got this bus. I'm going to hook it back up again because it really annoys my neighbor, and for safety of course.

[cadillackid]

be sure you are testing them with the engine running, on some of the transmissions, the backup lights are a pressure switch that when the trans enters reverse gear the lights come on...
-Christopher

[tlbeck1985]

Originally Posted by cadillackid

be sure you are testing them with the engine running, on some of the transmissions, the backup lights are a pressure switch that when the trans enters reverse gear the lights come on...
-Christopher

Great thought! Off all of us combined can figure out just about anything I would imagine.

[Moose]

All fuses test ok but there are many empty spots in the fuse panel. Could one of those be the backup lights fuse. Anyone have a diagram or listing of fuse panel?

[Robin97396]

Moose, any chance you'll flesh out your information with bus type, size, year, etc.

Generally speaking, things just don't go that easy while working on a bus. Diagrams are few and far between. You know the information is out there, somewhere.

I can never find a fuse when I need it, so I fill those empty fuse blocks up with a variety of different size fuses. Finding that little fuse puller is what's difficult. Those extra fuses sometimes make things work that didn't previously work. Experimentation is still alive and well in my electrical repair box.

[Moose]

added to my profile 1996 TC2000 FE 5.9

[Robin97396]

Earlier I was trying to figure out what part of the country you're in.

I believe I found your fuse box schematic. There's a photo in a separate thread.

[Jolly Roger]

Mine was the pressure switch in the tranny(545) that was bad. I was able to verify that it was the problem with the bus parked and in neutral by pulling the wires at the switch and jumper them together to make the connection.

[Moose]

Which tread is it in?

[frenchbean]

Thomas 1998, model 3800

Trying to get it inspected.

B/U fuse keeps blowing up. I replaced it with a 25 with same results.The lights are good. Good ground contact at the b/U lights.

I'm new to this. I'm trying to follow the wires from the fuse box to the back up lights, but not idea at this point where they go. Was thinking about opening up panels, but would prefer an easier route!

Any advice?

Thanks.

[Robin97396]

Some of the wiring systems have numbers printed on the wires so you can identify them at the other end. Then some other buses have all the wire the same color.

[cadillackid]

Originally Posted by frenchbean

Thomas 1998, model 3800

Trying to get it inspected.

B/U fuse keeps blowing up. I replaced it with a 25 with same results.The lights are good. Good ground contact at the b/U lights.

I'm new to this. I'm trying to follow the wires from the fuse box to the back up lights, but not idea at this point where they go. Was thinking about opening up panels, but would prefer an easier route!

Any advice?

Thanks.

which transmission do you have? allison AT545? the backup lights operate from a pressure switch on the side of the transmission... that connector is a good place to start.. sometimes the wires get scuffed. and shorted out..

when you replace the fuse, does the fuse stay good until you first place the bus into reverse? or does the fuse Blow up as soon as you turn on the ignition even when the transmission is in 'N'?

if the fuse stays good until you go to reverse, chances are you dont need to trace from the fuse box, you need to start at the transmission and work back..
-Christopher

[frenchbean]

It is an Allison transmisson.

The fuse blows up as soon as I shift it in reverse.

I looked behind the fuse panel and I notice a red(pinkish) wire with the number 135B.

When I checked out the wires at the B/U lights, one was blue with the number B135 (inversed numbers) and the other wire was blue and white with no number on it.

I guess I'll have to crawl under the blue in the morning to check out the pressure switch you're talking about.

Will let you know.

Thanks for the advice.