No crank no start

[Sberry65]

I have a Chevy express 4500 and it won’t start, started perfectly fine 12 hours before, no stutter or anything. I have never had problems starting it before. I moved it a little around 7 at night then the next morning I tried to start it and it wouldn’t even crank. We checked the voltage on the battery and the starter while trying to start it, there is no voltage drop. We bench tested the starter and it works, and we checked the battery connections and starter connections and all seem to be tight. Any suggestions?

 

[Simplicity-SKO]

Sorry to hear this. I'm in the same situation, 3rd time, so I feel your pain.

I'm assuming it's a gas engine, cut-a-way van and has a computer.

Does it crank when you turn the key?

If yes, does it just crank or does it sound like it's trying to start?

 

[Sberry65]

Yes it’s a gas cut away, and no there is no crank it just clicks once

 

[Timeline]

Wiggle the shifter with key turned to check if it's a neutral safety switch. that's a long shot guess but my bus does that.

 

[Simplicity-SKO]

In my situation it's because the ECM is not getting power.

If it's a cut-a-way, it probably doesn't have a neutral lockout.

Are any interlocks active, like on your emergency door exit?

Do you have a wheelchair lift?

 

[Sberry65]

I’ll give it a try in the morning when I go back over there! Thanks!

 

[Sberry65]

What do you mean by interlocks?
It does not have a wheelchair lift

 

[rossvtaylor]

What do you mean by interlocks?
It does not have a wheelchair lift

Most, or all, of the modern buses have interlocks which prevent the bus from starting or prevent the release of brakes if there are certain conditions...like a door open or the "child safe" button in the back not being reset. If you read through these forum threads for any length of time, you'll see posts that essentially say, "I took out a bunch of wires and now my bus won't start." Assuming you didn't remove any wires, the same can happen if an emergency exit is open. Or if the wheelchair lift is on, which is why he asked.

I'll say, though...hearing a click, as you mentioned, sure sounds like a low battery charge. I just did that last week, by accidentally leaving a flasher on.

 

[Simplicity-SKO]

It's good that you don't have a wheelchair lift because they can have a lot of safety wiring involved.

Interlock basically means it locks out the bus from doing something, generally starting, and in most cases it's like a little slide lock. If the lock is in place, so you can't open the emergency door then generally a buzzer will sound. If the buzzer is not present then you may not be alerted to the slide lock being locked. And this could prevent the bus from starting. That's the thing about school buses, they have all sorts of safety wiring.

What year is your bus? A suggestion is that you complete your profile with the information about your bus so people who are trying to help can just look at your profile information and know what year, type of bus, engine and transmission you have.

If you're starting batteries are charged up and it's not even cranking, and you have a computer for your engine and probably your transmission (assuming this because the e450 is a fairly new model, at least in relation to the age of most of the skoolies), then if your engine computer aren't getting power and waking up, so they can't tell the bus to start.

In a cutaway van, assuming you're gear shift is on the steering column and you have a park setting, you need to make sure that it's in park. That can keep it from starting. Just because the arrow indicates it's in park doesn't mean electrically it considers itself in park, so move the gear shift a bit and then put it back in park and try to start it.

You also have relays that need to all be operating to start the bus. Generally there's a start relay, an ignition relay, crank relay, computer relay, etc.

If one of these relays is not working properly then that can keep the bus from starting. Knowing how to read and interpret the relay and test them is a good skill to have.

A general automotive relay is four or five pins and two of those pins are the positive and negative to an internal coil, and when the coil is activated it either opens or closes an internal switch which allows current to flow. Look it up on YouTube to learn how to identify and test the relays.

All of those relays on my bus test well, but my bus still doesn't start. That's why it's sitting a half a state away at the dealership. So if your bus is on your property, count your blessings.

Electrical Gremlins are the worst. There's so much wire, and it's hidden all over the place. Yeah, learning how to identify the components involved in your bus starting, and testing those components, will really benefit you in solving this problem and other issues down the road.

If you don't have a multimeter, you need to get one and understand how to use it for testing voltage, resistance and continuity.

Another really good testing tool is a tracer, which means you connect one part of the tracer to a wire and then use the other part of the tracer to follow where that wire goes. Again, Google this.

I know this is a lot of information, but having the right tools, knowing how to use them and knowing how your system works will really be a great investment and make you more independent in resolving issues with your bus and other people's buses!

In summary, you got a bunch of wires, connections, switches, etc. And if one of those is bad it can shut you down. Finding that gremlin is the key.

 

[cadillackid]

the shifter is a good bet.. and on damn near every GMC ive ever owned I either end up witgh loose wires on the big starter terminal or the solenoid goes bad.. it will have a Neutral safety switch on the transmission. the neutral safety switch is on the side of the transmission at the shifter linkage.. if its mis adjusted the computer will not allow the engine to crank..

 

[Sberry65]

Omg thank you so much !! It was the interlock, the emergency exit was locked, unlocked it and it fired right up!! Thank you all so much I would have never guessed that!