Bus wont start

rustplug · 11-24-2016, 05:43 PM

I have a 1990 TC2000 and I went to check it out this morning and there was no air in the brake system and it wouldnt start...Are these to things related? Like a fail safe for the bus not to start if there is low pressure in the brake system....Anyone know anything about this?

AlleyCat67 · 11-24-2016, 05:56 PM

It should still start with no problems, you just won't be able to release the parking brake until the pressure builds up.

Bus Driver · 11-24-2016, 06:03 PM

I don't know anything specifically about your bus, but generally speaking it makes no sense to have a device that prevents the bus from starting due to low air pressure. The engine needs to run to build air pressure, and it isn't uncommon for the air pressure to be low when you start it up, especially if it has been sitting for a while. The safety device on a bus with air brakes is that when the pressure drops below a certain level the the brakes engage and the bus won't budge. On my bus if it has sat for more than a few hours the air pressure is zero (think I have a leak somewhere) and I need to start the bus and let it idle for about 5 minutes before the brakes release and I can move.

AlleyCat67 · 11-24-2016, 06:40 PM

Something I just thought of..... if your bus is like mine all of your emergency exits have to be closed and latched before the bus will crank. Mine takes it a step further in that the engine access door also has to be closed. So check all your emergency exits and make sure they're all closed and latched.

Rameses · 11-24-2016, 07:59 PM

Quote:

Originally Posted by AlleyCat67

Something I just thought of..... if your bus is like mine all of your emergency exits have to be closed and latched before the bus will crank. Mine takes it a step further in that the engine access door also has to be closed. So check all your emergency exits and make sure they're all closed and latched.

Does the engine crank but won't fire, or is there absolutely nothing when you turn the key?

If there's absolutely nothing, the above suggestion is a good place to start. If it cranks but won't fire, it's something else.

And it's definitely not the case on something built in 1990, but for trivia's sake, it's possible that no air pressure would keep an engine from being started. They were never common, and have been out of production for years, but once upon a time there was such a thing as an air starter. If your air leaked down, you had to find a way to charge your air system in order to start your engine. And you can recognize something with an air starter from a long ways away because of the sound they make when you hit the key.

rustplug · 11-25-2016, 10:19 PM

Thanks for your ideas, but check this out the bus was in neutral but the switch is sensitive, moved it in and out of neutral a couple times and it fired right up, now i need to find the leak in the air brake system.

AlleyCat67 · 11-25-2016, 10:24 PM

Neutral safety switch is slightly out of alignment then, should be a fairly simple matter to correct it.

Glad it was something minor.

cowlitzcoach · 11-25-2016, 11:37 PM

You gotta love those cheap fixes.

I had one bus that as you got into the driver's seat it was very easy to knock the shift controller out of neutral and not know it.

I think every single one of my drivers called me to tell me the bus wouldn't start.

I would ask things like were the buzzers buzzing or not? If they were buzzing did they check to see if the shift controller was in neutral. Invariably the answer was it was now.

cadillackid · 11-26-2016, 08:14 AM

its pretty normal for your air pressure to be low if it sits overnight or a few days.. esp if you have an air ride suspension.. those suspensions will continue to use al ittle air even when parked, esp if you are working in oyur bus where it may bounce up and down inside form you walking inside it... that can run your air pressure by itself down to the protection valve cutoff of 55-65 PSI.. then any small leak you'll chase for a long time.. I used to obsess over wanting to have air pressure for days at a time.. but i dont worry anymore.. my bus will hold air for a couple days then be down to about 10-20 PSI... the compressor makes up air very quickly so unless you have an obvious worn pipe or line its not going to hurt anything.
-Christopher

Marceps · 12-14-2016, 01:00 AM

Well, this thread has answered some questions for me, as I am in the exact, same situation. Turning the key produces nothing but silence. The issue began after letting the bus sit for less than three weeks. I have charged the batteries to full; head and cabin lights are bright as day.

My bus's transmission is automatic, so it can't be the same issue as rustplug's. I will double check emergency exits but would appreciate any other ideas in the meantime.

AlleyCat67 · 12-14-2016, 01:15 AM

It's possible that the neutral safety switch is a little out of alignment, maybe try shifting out of neutral and back in.... also if you have a RE check the switches in the back to make sure nothing is amiss. If you have the switch set wrong there you can turn the key all day and nothing will happen.

Marceps · 12-14-2016, 01:33 AM

I hadn't thought of the RE switches. Thanks!

I "shift gears" with two push buttons. In between them is display indicating the current maximum gear (1-6, N). The display doesn't light up without the bus running. Should I try pushing buttons regardless?

rustplug · 12-14-2016, 08:22 AM

My bus is automatic as well.

Versatile · 12-14-2016, 08:40 AM

Have you cleaned you battery connections. How old are the cables? Start at the beginning.

AlleyCat67 · 12-14-2016, 09:52 AM

With a push button shifter that option will not come into play, it only applies to manual shifting via a lever.

cowlitzcoach · 12-14-2016, 12:21 PM

Quote:

Originally Posted by AlleyCat67

With a push button shifter that option will not come into play, it only applies to manual shifting via a lever.

That is not necessarily true.

I have seen where electronic shifters have gotten stuck between gears when the voltage was below 12 volts.

DoubleO7 · 12-14-2016, 01:59 PM

Quote:

Originally Posted by Versatile

Have you cleaned you battery connections. How old are the cables? Start at the beginning.

Hopefully it does not have the crappy GM side mount style battery terminals.
Whoever designed those should have been shot.

Marceps · 12-18-2016, 05:36 PM

Update: The bus runs great! It started up immediately, in -10° C weather. I started the bus with the manual start unit in the engine compartment... Why didn't anyone suggest that? Did I miss something? It's a great diagnostic step, probably the first thing you'd want to check every time.

In any case, a floor heater immediately started leaking coolant, so I won't be starting the bus until all three heaters are taken out of series. The alarm buzzer was sounding in the cabin. I would not be surprised if simply letting the bus run through its startup procedure and return air pressure to normal solves the issue.

Quote:

Hopefully it does not have the crappy GM side mount style battery terminals.

Is that the type shown in the attached photograph? The pull-out tray won't budge... It's rusted to hell and back.

milkmania · 12-18-2016, 07:07 PM

Quote:

Originally Posted by Marceps

Is that the type shown in the attached photograph? The pull-out tray won't budge... It's rusted to hell and back.

If I'm not mistaken, those are group 31 series... But, I can't tell from pic if they're lead terminals or threaded studs... Look like threaded studs, such as this:

ol trunt · 12-18-2016, 07:20 PM

I enlarged the pic--threaded

You may also like: