Can't reach the magic 12v

[Iheartbus]

Not really, we just checked it after the bus died while driving. The dash kept resetting the RPM's and the speedometer, it would turn up, stop for a sec, then turn off, and repeat this for at least a good 5 minutes. Then it basically died, then started spinning out of control, and then the engine started sputtering and eventually I lost a ton of power and the check engine light came on. We stopped and checked the battery voltage and the alternator to see what was going on. We sprayed some cleaner fluid on t he batteries and scraped the contacts to remove debris and it eventually started back up. It was around this time we noticed that the dash always shows 11v. It hasn't freaked out again since.

This all happened when we purchased it, and it happened near the end of a 2 hour drive.

[Stu & Filo. T]

Ok I need clarification , reading your Origanal first post my understanding was checking the batteries while separated your getting 12.4v, after putting them in the bus & connecting cables you are just getting over 11v while NOT RUNNING, are you saying that after starting it your only getting 11V?

[Stu & Filo. T]

Ok sorry I went back & slowly read the other post,, forget my idea

[Iheartbus]

Originally Posted by Stu & Filo. T

Ok sorry I went back & slowly read the other post,, forget my idea

Yea it says 12.4 when they are connected, but once the engine starts the dash says 11v.

[BlackJohn]

Originally Posted by family wagon

A grid heater is in the intake and is powered by the 12 volt system. Looking down into the intake, it looks like a stack of zig-zag plates not unlike the fins on a radiator. It pre-heats the air as it flows into the engine.

The mains plug you spoke of goes to a block heater. That heats the coolant and in turn warms the pistons and cylinder walls. It's different from glow plugs or grid heater which both work to heat air directly, but it works in concert with those for starting in cold weather. There can be a lot of different electrical-powered heaters on a diesel engine!

You could take the volt meter to the output stud on the back of the alternator and measure from there to the alternator case. If you don't have at least 13.2 volts there, and preferably higher like 13.5 to 13.9 volts or even a little more, then either there's a whole lot of load pulling the alternator down or else it just isn't producing like it should. While you're in the neighborhood, disconnect inspect and re-connect whatever connectors are on the alternator.

Just to clarify: do I understand correctly that the battery voltage is lower when the engine is running, even after it's warmed up, than when it's not running?

Great explanation family wagon of the grid and block heaters. two different animals for sure.

Perhaps the voltmeter isn't really accurate. That is common in older vehicles, they loose calibration in service.
So, retest what you have coming off the alternator again for voltage as was explained by fwagon. Tell us what that reads going back from there and at the battery, with bus running of course. Just be careful in there and be sure you do the reading right. A zero reading means change the leads from hot to ground and vice-versa. Then the meter will tell you what the situation is. A good or not so good alternator.

Just for those who might have grid heaters, NEVER use any starting fluid to get the bus running You will see a rather quick explosion, engine fire and possibly loose the bus, not to mention a lot of bare skin.

[Iheartbus]

No starter fluid, ty! I don't have a meter so I can't do the test right now, but as soon as I can I will give it a shot. For now, I just gotta get the brake lights to work again.

[family wagon]

OK, don't take this the wrong way, but... we've gotta get you a meter and training on how to use it. It'll be invaluable for both the battery and the lighting challenges you're facing.

Sparkfun in Colorado has a free How to Use a Multimeter tutorial on their web site. It's directed toward the relatively new electronics hobbyist but teaches principles that would fairly easily translate to vehicle electrical troubleshooting. They sell the meter shown there for US$15, but something comparable can be had at any number of local retail and online outlets.

[Iheartbus]

Thank you I appreciate it! I'll post a pic of what I am working with soon

[Iheartbus]

So this is what i'm working with right now. The panel was cut out, leaving all these stupid wires here that I have no clue what goes to which. I looked on blue bird's website and put in my body number and vin, and wouldn't you know it, the wire schematics are unavailable. So, I'm left without any back brakes, night lights, etc. Its really frustrating!

I also posted the battery I'm using, I have 2 of the same brand in parallel for 12v 200mAh

[milkmanchip]

That box was a light indicator so anytime you turn a light on or hit your brakes or turned the school bus yellow and red flashers on those lights would come on on that box to show that they're working I think if you put all the colors together and wire nut them together you'd be all right you're just closing the circuit eliminating the Box

Sent from my Z981 using Tapatalk

[family wagon]

It's bizarre that somebody would chop out that monitor panel. Nevertheless, what's done is done..

It appears the four sub-bundles are cut at different lengths. You may be able to get most of the wires matched up simply by the logic that what's long on the monitor panel must go to something that's short on the wall. Look carefully at the wire jackets. Do they have any kind of text or other marking printed on them? If the cut broke through some kind of print on the wire, the two sides could be matched based on that.

Is there any kind of legend printed on the back of the monitor panel? That could help us determine which colors correspond to which functions. It may well be that milkmanchip is right: just pull all the greens into one big wire nut, all the reds into another, the yellow-with-black-tracer into a third, and so on.

[Iheartbus]

Really? Its ok to put those colors together without blowing the fuses?

[Iheartbus]

Originally Posted by family wagon

Is there any kind of legend printed on the back of the monitor panel?

I looked and there doesn't appear to be a legend, just the spots where it was plugged in. There seems to be a lot of ground wires up top, at least i think they are ground, they are all grey. Near the bottom is where the colors come in. I could go by the lengths but honestly its too insignificant to really tell

[BlackJohn]

Originally Posted by milkmanchip

That box was a light indicator so anytime you turn a light on or hit your brakes or turned the school bus yellow and red flashers on those lights would come on on that box to show that they're working I think if you put all the colors together and wire nut them together you'd be all right you're just closing the circuit eliminating the Box

Sent from my Z981 using Tapatalk

I don't think I would be that brave to just putting matching wire colours together. In vehicles there doesn't seem to be any standards among different manufacturers. Most people would think grren for ground,but not necessarily so.

So, like was advised,get a meter and practice with it. Strip all the wire ends but leave them in bundles as they are because that is part of the solution. If your battery is hooked up then test each wire,you'll likely need a helper. So you thru each bundle checking for voltage to ground. Don't depend on what wire you think might be a ground, be precise and connect your meter lead directly to the body or some ground you can make up for convenient testing.

You know this takes time but it is the only way to correct that unfortunate mess. Stay cool man. As you can see many have your interests at heart here.

I see the battery is on a charger and have no idea how good or bad your cables are. What is 220mAH? That can't be correct at all.

[BlackJohn]

Can you post pics of that yellow box so I can see the back clearly and then the same for the front. It might be worthwhile saving that monitor for your own use.
Thanks in advance.

[Robin97396]

I don't know if you've noticed but recently on youtube it seems to be a popular trend to take an exterior light monitor from a bus and hook them up in your car. Purpose unknown.

[roach711]

If you can find a model number on that panel you may be able to get installation instructions from the mfgr. That would tell you what wires do what.

Failing that, in the short term you'll need stop, turn, reverse and tail lights to get you back on the road and probably the quickest way to find those is to test each wire with a voltmeter. Test each wire with no lights on then test again with only the tail lights on, then only the brakes pressed, etc. It will take some time but it's doable.

Once you find the source side wires you can then touch like color wires together and see what comes on. Just make sure that only one wire has power before connecting them together.

[roach711]

Here's the manufacturer:

http://www.aeroflash.com/aeroflash_w...reak_light.php

[Iheartbus]

Originally Posted by BlackJohn

Can you post pics of that yellow box so I can see the back clearly and then the same for the front. It might be worthwhile saving that monitor for your own use.
Thanks in advance.

I would love to put it back in tbh, Being able to see if a light is ever out is extremely valuable to me.






As requested ^_^

[Iheartbus]

Originally Posted by BlackJohn

I see the battery is on a charger and have no idea how good or bad your cables are. What is 220mAH? That can't be correct at all.

I just meant that I have the 2 batteries in parallel for double the longevity, rather than just using 1 battery.