URGENT: No Crank. Bus stuck. - Page 3

BeNimble · 03-12-2021, 03:28 AM

Well the real problem here is the cost to tow a big school bus is so expensive, one tries to avoid it if at all possible, rather than just pay $100 to have it towed home or to somewhere else where you can work on it.

mokibrabrant · 03-12-2021, 03:42 AM

From what I've read a $100.00 tow us the least of his worries.

Truthseeker4449 · 03-12-2021, 05:29 AM

The bill to move the bus probably starts at $100 for the hookup fee and is charged hourly from there often to a steep rate. It's not like towing a car, the driveshaft or axle shafts must be pulled to avoid damage to the transmission. The front axle gets chained to the tow truck and air lines must be run to the bus's brake system to release the brakes. Tow truck guys are not required (and in some cases prohibited) to reinstall axle shafts or drive shafts for liability reasons. I used to work for a company that used to get buses towed down from Baltimore often and the bills were sometimes $300.

Another option since the OP is in a decently populated area is calling out a road tech. He won't be cheap either, but the tech can probably get the bus going again.

OP, By total chance, have you touched your emergency exits at all in this process? You didn't lock any of them? Otherwise I second verifying the computer is actually doing its job by checking for output. Put your hand on the glowplug solenoid, you should feel it click. You can also check it with a test light, it will have a constant power feed and a switched wire from the PCM. In the last picture, it is the solenoid to the left of the oil fill that is dead center in the picture.

If your friend is able to help you, please be mindful of where your body and anything hanging off of it is at all times, it would be a terrible thing if you got caught in something while the bus is cranking over. Good luck.

joeblack5 · 03-12-2021, 06:30 AM

Simplicity,. Hope you have time to look up how the glowplug relay looks and where it is located on your bus..google is your friend..

Do you have a multimeter and know how to use it?
Do you have a test light that works on 12 volt?

Do you by chance have a lockout switch on your battery compartment door?

With problem like this there are three approaches.

1 you have tons of experience and know what to look for.
2 you start from the battery and work your way thru the chaos to the engine.
3 you start at the engine and work your way back to the battery.

In your case with lights coming on but no engine related lights ... Wait to start, glowplug light etc . I would start at the engine.

The quickest way is ,as mentioned , put your hand on the glow plug relay and feel it click..
If not measure if you have voltage on the large connection with the big wire.. the other large connection has two slightly smaller wires that go to the glow plugs.

If no voltage then follow where the big wire goes and check for voltage there.

If you have voltage look for the ecm power relay
Again google is your friend..

Same story. Have some one turn the bus on contact and feel if that relay clicks.
If yes then verify the voltages on the two heavy wires.
If not follow the wire to the fuse box.

Measure the voltage on either side of the fuse for the ecm.

Report back.

Johan

Deezl Smoke · 03-12-2021, 08:12 AM

Hopefully you wont buy any more parts until you know what part to buy if any. Of course not being there in person it is difficult to be of any real help, but reading your info as it progresses, this issue still wreaks of connections, not parts. Not large parts anyway.

Quote:

My batteries were 7.5 years old, and while doing KOEO testing the headlights (running, not switched) were on. I charged the batteries overnight, it started right up and then I drove it for 20 minutes including on the freeway.

I parked it in front of my house and when I went out to start it, no crank. The engine guage lights that normally come on to the R of the speedometer were not showing up, but all the normal noises and the ABS light were.

The batteries would not take a charge and despite them showing 11.7v, I decided they had seen their days. I replaced them with the exact same batteries and they show 12.85v.

Yet, the same issue, no crank and the instrument lights that come on during the engine check are not showing up. What is showing up are a Brake and a Water in fuel light. I'm sure these are red herrings.

So when I bought a cat powered bus a few years ago that was put out of service a few months early because the bus died and had to be towed into the bus yard. No-one, including the "cat tech" hired in, could find the reason for the engine to just die and not start. I bought it for a towable conversion. I dont recall where or how I found the info, but turned out the buses of that area had a few inline higher amp fuses that were not in the diagrams. Traced wires, located fuses and sure enough, somewhat discolored and blown fuse. Replaced fuse and fired right up. Drove it to a better place to work on, and next day a local berry grower shows up and makes and off 5 times over what I paid. Bus project left my hands that moment.

Being you are in the area you are and me in a similar "political climate" as you, I feel your pain dealing with HOAs. One way to insure the bus can stay right where it is, is to put a sign on it "homeless felon inside". Done. The bus can't be towed.

ol trunt · 03-12-2021, 09:55 AM

"Being you are in the area you are and me in a similar "political climate" as you, I feel your pain dealing with HOAs. One way to insure the bus can stay right where it is, is to put a sign on it "homeless felon inside". Done. The bus can't be towed."

Ain't it the truth--LMAO.
Jack

Simplicity · 03-12-2021, 10:45 AM

If you knew me well, you'd know I spend way too much time on Google, Skoolie.net, reviewing T444E and MT643 documentation and scratching my head. While I'm not a gear head, I'm pretty smart and learn, but sometimes there's limited access to the right info, and then you look at a schematic and look at the panel and guess what, day don luk da sam'.

Per parts, Besides the two batteries, which I feel replacing 7.5 year old batteries isn't a bad expenditure, and an ignition switch, no other parts have or are planned to be purchased until I've identified the issue, or think I have.

Yes, I have a whole set of tools, including some you may be wondering what they are or wish you had one, and in general, I can MacGyver something if needed.

Thankfully, tomorrow is Saturday and I'm off through Monday, and it's actually warming up during the late morning to comfortably work under the bus.

So, with test light and multimeter in hand, I'll be poking in as logical a manner as possible. Albeit, I'm not so great with relays and such, but I'm learning.

Per the simple and obvious things like the door interlock system, they buzz like crazy if locked, and stop when properly unlocked. You can't leave them even half way, you have to slide them into a fully unlocked position.

Remember, it drove and ran great, then I parked it and the next time I tried to start it is when all this began.

Thank you for all those who are encouraging and giving me leads. I'm learning a LOT!

Can't wait to find the answer!

BeNimble · 03-12-2021, 11:00 AM

Quote:

Originally Posted by BeNimble

Well the real problem here is the cost to tow a big school bus is so expensive, one tries to avoid it if at all possible, rather than just pay $100 to have it towed home or to somewhere else where you can work on it.

If it was a van or truck, it would be ONLY $100, he could have it towed. Because its a school bus, it will be at least $500, probably $1000.
I just had my 22ft boxvan towed, it was $150. Most said it was too big.

Sorry I can't help with the actual problem, or add anything to the good suggestions already made. Having done an EFI engine swap on the vintage motorhome, I had to get the wiring diagrams ($10 from alldata) and trace all the wires, was a tedious job. This might be what is needed here, find where power should be and test if its there.

peakbus · 03-12-2021, 11:30 AM

We were camped a few years ago after torrential rain in OR and woke at 6am with the start beeper and all dash lights going as if the bus was trying to start, only it wouldn't do so when I tried. I had to disconnect the battery for it to stop beeping. The diagnosis eventually (I'll spare the long story) was no ground to the ECM. It had disconnected or come loose along the way. After the offending connection was repaired, all was good.

Simplicity · 03-13-2021, 10:34 PM

UPDATE:

We got the engine to crank by jumping "a" relay.

Is it okay to start it this way so I can park it in my driveway?

I say it that way because my rear electrical panel lists 7 relays, but there are only 5 physical relays, so we're trying to decipher with wire id numbers and tracing what the all are. (see pic)

We've been searching for the ECM relay, only to find it's labeled as CEC, consolidated engine controller, only used by Navistar.

We also have a Neutral Relay, but nothing in the diag manual used that term, so I'm assuming the neutral switch is the same thing.

Finally, we found a broken wire (see pic).

This is the male part of a connector. The socket is attached to one of the unknown relays.

It has three wires. One is common and the other two have diodes that loop back into the common. The diodes were each encased in plastic sheath. We found one diode wire broken.

The common wire goes to relay pin 86.
One diode wire goes to the rear ignition switch. The connection tones.
The other diode wire goes out to the wire bundle that feeds the panel.

We believe this is, or is part of, the no crank issue. Unfortunately, the wire lead broke right next to the diode body, so we could not solder it together.

In the June, 1997 diagnostic manual states the starter relay has an "internal" relay (this is external) to prevent voltage spikes.

I've reviewed docs and googled, yet have only found no replacement.

Please tell me if you know what this connector is.

TJones · 03-13-2021, 11:30 PM

You may be able to take the the connector to an international dealer along with the VIN and they might be able to identify the part and provide a replacement. The other alternative is if you can get a part # off of the broken diode and get a replacement from the interweb or electric components store.

Did that connector come out of the bottom of a relay?

Ted

Deezl Smoke · 03-14-2021, 07:56 AM

Nothing there is un-fixable. That diode setup is suspect. A diode, as you likely already know, is simply a one way gate. It makes sense in a multi switch system to have a gate, but that one looks like a shade-tree install. You can test a diode with a common, inexpensive multi-meter. In fact, a lot of multi-meters today have a "diode" setting.

Those connectors are available to buy. You can make, or have someone make a new connector and pigtail for you. I wish I could give you the trade name of that connector, but I dont have it right now. I am somewhat familiar with a few weatherpack and a few deutsch connectors. Potentially there is a premade pigtail for sale online somewhere.

Unpluggedone · 03-14-2021, 11:29 AM

If you jumped the solenoid terminals and it didn’t turn then the starter is bad. Find a starter shop as it’s not typically the actual starter motor but the contacts that get fried. Save you a bunch versus buying a new one

Simplicity · 03-14-2021, 02:45 PM

SOLVED!

The problem was the Diode I mentioned in one of my last three posts.

After identifying all the relays, it turns out the ignition relay, which is not mentioned in either the June 125 or December 190 version of the diagnostic manuals, uses these diodes.

After doing power testing of each relay socket, we reconnected the diode connector to its socket, twisted the two remaining leads from the connector together, KOEO and boom! All dash self test lights came on. After letting the self test complete, I bumped the key to crank and the engine turned.

All this as it started to rain.

Huge thanks to my friend who, as a commercial refrigeration contractor, has to trouble shoot electrical all the time, in looking at the yellowed out plastic covering that had been rubbed through, then pursued removing that covering to find the broken diode lead. From there, we just had to verify the relays and power voltages.

Why did this happen after three years of no issues, because in trying to resolve my tranny modulator issue, we had to fish around in the nest of wiring to identify and trace relay wires.

We don't think the diode lead shorted, because no signs of heat, but simply continued to rub and vibrate through the diode lead. Moving the wire nest just finished the job of breaking the wire lead.

Thanks again to all that provided input and encouragement. A lot of positive things came from this.