Hey guys, the bus nut I'm referring to in the title is me! I'm hoping that one of you Bus Nuts can save me :)
I've been dealing with an issue for over a year now. Basically when I hit a bump a certain way, I briefly loose all power to engine and electrical things like headlights, and dash lights. For the brief moment that the power is off, the "no charge" dash indicator light turns on and I also hear a clicking noise to the left panel of the driver seat which I think is a circuit breaker. But let me give you some more details.
I first noticed this problem not to long after I got it (and it wasn't a bump in the road), it would happen when I would rev it to high RPMs preparing to shift to the next gear. As long as I didn't rev to hard, it wouldn't happen... but that only ended up lasting about a week. For months after that, no amount of revving the engine would cause it to do it anymore.
I then started noticing these same characteristics when I hit a bump a certain way (mainly hard quick bumps like pot holes, or railroad tracks). I didn't notice it for a while. In the meantime I had an automatic transmission put in (boy is it nice!!!!) but I'm still experiencing the bump issue.
I have taken it to a good mechanic that has spent many hours looking for beat up wires, frayed wires, etc. He found some and fixed all of those. He even found one that he said was so barely touching that he didn't know how it was even working. This one went to an important solenoid. He thought that would have fixed it, but it didn't.
I've taken it back to him multiple times, and he says he has looked that bus over 100 times and chased wires, etc, and is stumped as to why it's still doing it. He thinks that it's potentially a solenoid somewhere that is cracked a little on the inside and is getting hot and a bump creates the momentary disconnection. But to me, that still doesn't explain the headlights turning off, or the circuit breaker clicking? Or does it?
What do you guys think this could be? Thanks for your help!
P.S. - the "no charge" dash light is also on when ignition is turned on, but engine is not started. (didn't know if that helped)
First place to check is a loose ground. Start at the battery and work your way back.
Hi Bryan,
I second the ground issue..
I personally chased a similar problem and found a corroded ground lug in my drivers
electrical box.
Good Luck
Nick-
Thanks guys! If this is truly a ground issue, then why would I still have enough power to turn on the "no charge" indicator light. It seems that I would have ZERO power? I'm I correct in thinking this?
More than one major ground...
Good luck, I feel your pain!
happy coaching!
buswarrior
Bryan my bus had a bare wire and every time it shorted out it tripped a breaker. As soon as the breaker cooled down everything worked again,almost to the second. I would check all the grounds and then check the main wires that supplied powder to everything that is effected . Hook up a battery charger, turn everything on, no radio,you want quiet so can hear elect. popping and cracking and start wiggling wires and you may find the problem. HTH,Glen
Thanks guys! I appreciate your input. When you say check the grounds, aren't there like many many grounds on the bus? It seems that the mechanic would have looked for this too right?
p.s.- I'm far from a mechanic :o
Dealing with connections made of different metals is a special headache. All such a joint needs to corrode is a little conductive liquid, such as dirty water, which acts as an electrolyte. That turns the joint into a weak battery.
Aluminum is especially difficult to maintain good connections. Bus frames and skins make rotten grounds and should be avoided. Another case is the starting circuit; the ground side needs to be only by battery cable all the way from batteries to the starter. The alternator output relies on the starter ground.
A failed ground in a bus can damage driveline components, so good grounds are very important.
Good luck.
Tom Caffrey
On a Mci 8 it happen to me. I got lucky and found it rite off. Was one of the relays with a bunch of pins on bottom that had a bad connection in socket. cleaned up reinstalled and no problems for the next several years I owned it. Also check for a pin/socket that has been pushed down to far in holder. Bob
Relays become weak over time they are just a coil I would be looking for a bad relay on the headlight system if the grounds are all good and that is a 12 volt system check and be sure no one has installed a 12v relay to fields on the alternator it requires a 6 volt relay
Initially I figured the clicking you hear is probably the headlight relay shutting off, which of course is why the headlights go out.
But in looking at the 4107 schematic, it appears there is no headlight relay. The headlights are switched directly from the hot bus.
That means you are losing power in the 12v bus.
If it was just your generator, then you wouldn't lose power to the headlights because the batteries would continue to power the bus bar. So,
the problem is probably between the batteries and the main 12v bus in the driver's compartment. It's the hot wire, not the ground. Check
the connections of the cables on the battery junction stud.
According the schematic I have, there's a 00 wire from that stud that feeds a bus bar in the ventilation compartment. Need to check this
connection. Then, the main bus bar is fed from a 90 amp circuit breaker on the ventilation bus bar. Need to check this. It's possible that the
circuit breaker is corroded or loose, or the connections on the bus bar or the wire off it are corroded or loose.
Then, check the connection at the main bus bar. It appears there are potentially 5 wires connected at the main bus bar where the feed comes
in from the ventilation bus. This is a prime location for loose wire or corrosion.
The click you are hearing is either your engine run magnetic switch or your generator magnetic switch. Most likely, it's the engine run switch, since
it's coil is fed from the 12v bus bar, through the engine run switch whereas the generator magnetic switch coil is fed from the generator relay.
The only thing I can't figure out is the part about the "no charge" light because none of the schematics I have show a generator tell tale light so I can't
figure out how it's connected and why it would be on if the bus bar loses power.
Quote from: gumpy on January 20, 2015, 06:58:13 AM
Initially I figured the clicking you hear is probably the headlight relay shutting off, which of course is why the headlights go out.
But in looking at the 4107 schematic, it appears there is no headlight relay. The headlights are switched directly from the hot bus.
That means you are losing power in the 12v bus.
If it was just your generator, then you wouldn't lose power to the headlights because the batteries would continue to power the bus bar. So,
the problem is probably between the batteries and the main 12v bus in the driver's compartment. It's the hot wire, not the ground. Check
the connections of the cables on the battery junction stud.
According the schematic I have, there's a 00 wire from that stud that feeds a bus bar in the ventilation compartment. Need to check this
connection. Then, the main bus bar is fed from a 90 amp circuit breaker on the ventilation bus bar. Need to check this. It's possible that the
circuit breaker is corroded or loose, or the connections on the bus bar or the wire off it are corroded or loose.
Then, check the connection at the main bus bar. It appears there are potentially 5 wires connected at the main bus bar where the feed comes
in from the ventilation bus. This is a prime location for loose wire or corrosion.
The click you are hearing is either your engine run magnetic switch or your generator magnetic switch. Most likely, it's the engine run switch, since
it's coil is fed from the 12v bus bar, through the engine run switch whereas the generator magnetic switch coil is fed from the generator relay.
The only thing I can't figure out is the part about the "no charge" light because none of the schematics I have show a generator tell tale light so I can't
figure out how it's connected and why it would be on if the bus bar loses power.
Gumpy, thanks for looking into this so deeply. You definitely know more than I do, but I'm determined to fix this. I just have a few questions. When you are referring to the ventilation bus compartment, you are referring to panel beside the driver seat correct? Also, I'm a little confused on what you mean when you say "generator", If you are referring to the actual generator we use for DC power on the bus to power fridge, etc, then that isn't even hooked up on this system, it's separate, but maybe you mean something else when you say "generator"? Thanks for the clarification.
And again, thanks so much for taking the time to look into this with the details! :)
Quote from: Bryan on January 20, 2015, 07:56:21 AM
Gumpy, thanks for looking into this so deeply. You definitely know more than I do, but I'm determined to fix this. I just have a few questions. When you are referring to the ventilation bus compartment, you are referring to panel beside the driver seat correct? Also, I'm a little confused on what you mean when you say "generator", If you are referring to the actual generator we use for DC power on the bus to power fridge, etc, then that isn't even hooked up on this system, it's separate, but maybe you mean something else when you say "generator"? Thanks for the clarification.
And again, thanks so much for taking the time to look into this with the details! :)
No. There's evidently an electrical panel of some sort inside the compartment where the heater and air conditioner blowers are located, or maybe where the condensor fan is. I'm not familiar with that bus, but typically the A/C compartment is located in front of the first bay. Maybe someone with more experience with the GM buses will chime in.
In the manual (Sec 7, pg 123) it says: "Ventilation compartment apparatus panel is located in the ventilation compartment on the lower right-hand air duct plate assembly. Components of the ventilation compartment apparatus panel are identified in figure 9 on next page."
By generator, I mean the alternator. In the schematics, they refer to it as a generator. I believe that early on, they used a generator and the rectifying diodes were separate, but not sure about that. The nomenclature still refers to the alternator and related components as a generator. The terms come from the schematic.
By the way, do you have a maintenance manual? Id so, do your electrical schematics show a "no charge" tell tale? Is so, can you scan it or photograph it and send me a copy?
The ventilation compartment is the first door to the left of your entrance door. The relays he is talking about are the two top round relays high up on the left wall behind the air tank. One of those wires go straight up to the bus bar beside the driver seat
Try turning on the run switch and headlights. Have somebody go in and try to wiggle that main wire on the the bus bar and see if anything blinks. I would take the main wire from the left relay to that bus bar in driver control panel loose at both ends and check for continuity end to end and to ground. If it shows ground it is damaged someplace.
As you have found out, that is a hard one to find. Try and wiggle as many of those wires going up there that you can and watch your lights for any response. It is a loose wire or a damaged wire someplace.
You really need the CD with your manuals and all the wiring diagrams.
Don and Cary
Quote from: gumpy on January 20, 2015, 09:31:42 AM
No. There's evidently an electrical panel of some sort inside the compartment where the heater and air conditioner blowers are located, or maybe where the condensor fan is. I'm not familiar with that bus, but typically the A/C compartment is located in front of the first bay. Maybe someone with more experience with the GM buses will chime in.
In the manual (Sec 7, pg 123) it says: "Ventilation compartment apparatus panel is located in the ventilation compartment on the lower right-hand air duct plate assembly. Components of the ventilation compartment apparatus panel are identified in figure 9 on next page."
By generator, I mean the alternator. In the schematics, they refer to it as a generator. I believe that early on, they used a generator and the rectifying diodes were separate, but not sure about that. The nomenclature still refers to the alternator and related components as a generator. The terms come from the schematic.
By the way, do you have a maintenance manual? Id so, do your electrical schematics show a "no charge" tell tale? Is so, can you scan it or photograph it and send me a copy?
I do have the manual. I will be looking for that and will send you a picture if I can find it. Thanks!
Ok and what exactly exactly is the bus bar? Sorry
Quote from: Bryan on January 20, 2015, 11:29:48 AM
Ok and what exactly exactly is the bus bar? Sorry
The bus bar would be the metal common bar that all the circuit breakers are connected to. There are photos in the manual. Section 7.
Don has a good point regarding the continuity testing, and possible grounding. I don't think the main wire is grounding out, though, because you
said the disruption is very brief. If it were a short on the wire, the circuit breaker would probably trip and it takes awhile for them to cool down
enough to reset.
That is where I keep all my booze :P
But really, it should be a long metal bar with a bunch of positive wires connected to it. On my 4104 there are several bus bars in several locations.
Quote from: gumpy on January 20, 2015, 09:31:42 AM
No. There's evidently an electrical panel of some sort inside the compartment where the heater and air conditioner blowers are located, or maybe where the condensor fan is. I'm not familiar with that bus, but typically the A/C compartment is located in front of the first bay. Maybe someone with more experience with the GM buses will chime in.
In the manual (Sec 7, pg 123) it says: "Ventilation compartment apparatus panel is located in the ventilation compartment on the lower right-hand air duct plate assembly. Components of the ventilation compartment apparatus panel are identified in figure 9 on next page."
By generator, I mean the alternator. In the schematics, they refer to it as a generator. I believe that early on, they used a generator and the rectifying diodes were separate, but not sure about that. The nomenclature still refers to the alternator and related components as a generator. The terms come from the schematic.
By the way, do you have a maintenance manual? Id so, do your electrical schematics show a "no charge" tell tale? Is so, can you scan it or photograph it and send me a copy?
[/quote
This is the image of the dash in my manual but this doesn't look like my dash in real life
](https://busconversionmagazine.com/forum/proxy.php?request=http%3A%2F%2Ftapatalk.imageshack.com%2Fv2%2F15%2F01%2F20%2F6921103ded365fdff08a5296ba2e5212.jpg&hash=21a929f4ad8dccf16972c73118d1dffbd92316e5)
And here is my real dash. Excuse the green tape. The no charge light is actually hidden by the center of the steering wheel. You can almost see it. This was the only picture I could find until I get back to it shortly
(https://busconversionmagazine.com/forum/proxy.php?request=http%3A%2F%2Ftapatalk.imageshack.com%2Fv2%2F15%2F01%2F20%2Fb9c22cbfae32afb3551e3e5212a7eba8.jpg&hash=70c2ac77eb92ead6ef1c3c6793f9b27a15ce4cc3)
I had a problem with the system shutting down momentarily that turned out to be a bad main switch. When you turn the main switch on and off do you hear the same clicking sound in the side panel?
Quote from: Lin on January 20, 2015, 12:08:55 PM
I had a problem with the system shutting down momentarily that turned out to be a bad main switch. When you turn the main switch on and off do you hear the same clicking sound in the side panel?
While a good point, according to the GM 4107 manual I have, the headlights are attached directly to the 12v bus bar. There's no relay controlling them, so it seems even with the main switch
on, the headlights could still be activated.
Bryan, maybe you can clarify that. Can you turn on the headlights if the run switch is off?
But, it could be a problem with the battery disconnect switch, I think, depending on which side of the battery junction post it's on.
The photos of the dash in your manual look like what I have. See if your schematics show a "no charge" tell tale or generator tell tale or something like that. I can't find any reference to one in the manual.
I suspect that maybe your bus is newer than my manual, or that is an add-on.
Gumpy, it appears that we are looking at the exact same manual. I'm trying to learn something here. Is the ventilation compartment apparatus panel fed directly from the battery stud? Or is it connected somewhere into the battery compartment apparatus box?
Lastly, yes I can turn headlights on if run switch is off.
Quote from: Bryan on January 20, 2015, 12:56:12 PM
Gumpy, it appears that we are looking at the exact same manual. I'm trying to learn something here. Is the ventilation compartment apparatus panel fed directly from the battery stud? Or is it connected somewhere into the battery compartment apparatus box?
Lastly, yes I can turn headlights on if run switch is off.
The feed should come directly from the battery compartment stud to the ventilation bus. If you look at the photo on pg 124 you'll see it coming in on the left side, second cable from the top. The top cable
on the left side is the one that goes to the drivers electrical box to power the 12v bus.
okay, I have a pretty major update! I turned the headlights on tonight and went and beat on the ventilation compartment apparatus where the battery wire is coming into it, and sure enough it make the head lights flicker, so I took it apart, sprayed some corrosion cleaner on it, did some minor wire brush cleaning, and put it back together... but it still flickers? I'm going to post a picture, the red arrow is where the battery power is coming in. The blue arrow is supposedly the circuit breaker that goes to the driver panel. But pretty much anywhere I beat on that bar, it makes the headlights flicker. What do you think?
(https://busconversionmagazine.com/forum/proxy.php?request=http%3A%2F%2Fs14.postimg.org%2Fp2pxza7w1%2FIMG_8316.jpg&hash=01f3eb34b5809db1d050e39bb915131eae73de5d)
Bryan the best tools I have for testing wiring is my test light and a three foot wire with alligator clips on each end, The wire lets you jump circuits while the test light is attached so it gives you a visual when the power drops out. Hook the light up, beat on the panel and if the light go off then take the jumper wire jump circuits till you find the culprit. HTH. Glen
Quote from: Bryan on January 20, 2015, 05:12:17 PM
okay, I have a pretty major update! I turned the headlights on tonight and went and beat on the ventilation compartment apparatus where the battery wire is coming into it, and sure enough it make the head lights flicker, so I took it apart, sprayed some corrosion cleaner on it, did some minor wire brush cleaning, and put it back together... but it still flickers? I'm going to post a picture, the red arrow is where the battery power is coming in. The blue arrow is supposedly the circuit breaker that goes to the driver panel. But pretty much anywhere I beat on that bar, it makes the headlights flicker. What do you think?
Following my previous line of thinking that the problem is loss of 12v to the front bus bar, I would, for testing purposes, take the wire off the blue arrow circuit breaker, and attach
it to the red arrow connection. I'm suspicious of that 90 amp circuit breaker.
I guess while you have them apart again, I would run continuity tests on both wires end to end, and while the test light is attached (see Glen's post above), wiggle the hell out of
the ends of the cables to make sure it's not a break inside the cable. Unlikely, but not unheard of.
And here's something else I just saw in the manual. Apparently there are multiple battery junction terminals. See pg 125. Two
of them seem to be pertinent to this discussion:
1. Battery compartment junction located on wall of rear baggage compartment above battery compartment, is accessible after removing guard mounted on top of battery compartment.
3. Ventilation compartment apparatus box battery junction, located on lower right-hand air duct plate assembly, is accessible through the evaporator compartment door.
I'm not sure about #3. Maybe that is the red arrow in your photo. Maybe there's another one in there. So, look where the text says and see if there's something else there. It seems that you are close to the problem if banging on the ventilation compartment causes the problem.
Another update! I ran a jump wire around that 90amp circuit breaker, (pretty much what you were saying about attaching blue arrow to red arrow)... beat on it pretty hard, and NO ISSUES!!! So I guess it has to be a problem with that circuit breaker. Where can I find a replacement?
THANK YOU!
Bryan am I hearing a big sigh of relief ? Hope you traced it down
Sent from my iPad using Tapatalk
Quote from: Bryan on January 20, 2015, 09:00:39 PM
Another update! I ran a jump wire around that 90amp circuit breaker, (pretty much what you were saying about attaching blue arrow to red arrow)... beat on it pretty hard, and NO ISSUES!!! So I guess it has to be a problem with that circuit breaker. Where can I find a replacement?
THANK YOU!
Very possible. And with all the corrosion I see in your panel, I would consider replacing a few other items in there. Before you go replacing hard to find parts, I would
recommend you bypass it completely as I indicated above, rather than using a jumper (you didn't say what size wire you jumpered it with), and take it for a long
drive to replicate the scenarios that were causing the problem to occur. Then, if you are sure it's not happening any more, replace the part.
I'm not seeing much in the way of 90 amp breakers (though I didn't search extensively), but according to the schematic that cable is a #1 so should be good up to about 130 amps.
You could go with an 80 amp breaker, or could probably go up to a 100 amp breaker with no issues. The 80 should be plenty for your needs. It looks like the headlights are probably
the biggest draw on that circuit. I assume all the interior lighting was replaced. Windshield wipers are on there, too. Not much else for current draw, so 80 amps should be sufficient.
I don't see a direct replacement, but here's one that I think will work, though you may have to move the bus bar assembly to fit it. Or, yo might have to make a new bus bar.
http://www.waytekwire.com/item/46913/HI-AMP-AUTO-RESET-80-AMP/ (http://www.waytekwire.com/item/46913/HI-AMP-AUTO-RESET-80-AMP/)
They have a similar 100 amp breaker, too, if you decide to go that route.
Waytek will also have a 20 amp panel mount breaker to replace that corroded one below.
BTW, you might be able to find one at NAPA or you might try a semi-truck parts house. Another option might be to call one of the local charter companies and
ask them if they might have one they'd sell to you.
Quote from: rgrauto on January 20, 2015, 05:41:43 PM
Bryan the best tools I have for testing wiring is my test light and a three foot wire with alligator clips on each end, The wire lets you jump circuits while the test light is attached so it gives you a visual when the power drops out. Hook the light up, beat on the panel and if the light go off then take the jumper wire jump circuits till you find the culprit. HTH. Glen
I'm going to have to make me one of those!
Quote from: digesterman on January 21, 2015, 06:25:37 AM
Bryan am I hearing a big sigh of relief ? Hope you traced it down
Sent from my iPad using Tapatalk
yes! very much a relief, this has been going on for quite sometime. I'm very happy to find the problem. Now I just gotta fix it :-)
Quote from: gumpy on January 21, 2015, 07:26:47 AM
Very possible. And with all the corrosion I see in your panel, I would consider replacing a few other items in there. Before you go replacing hard to find parts, I would
recommend you bypass it completely as I indicated above, rather than using a jumper (you didn't say what size wire you jumpered it with), and take it for a long
drive to replicate the scenarios that were causing the problem to occur. Then, if you are sure it's not happening any more, replace the part.
I'm not seeing much in the way of 90 amp breakers (though I didn't search extensively), but according to the schematic that cable is a #1 so should be good up to about 130 amps.
You could go with an 80 amp breaker, or could probably go up to a 100 amp breaker with no issues. The 80 should be plenty for your needs. It looks like the headlights are probably
the biggest draw on that circuit. I assume all the interior lighting was replaced. Windshield wipers are on there, too. Not much else for current draw, so 80 amps should be sufficient.
I don't see a direct replacement, but here's one that I think will work, though you may have to move the bus bar assembly to fit it. Or, yo might have to make a new bus bar.
http://www.waytekwire.com/item/46913/HI-AMP-AUTO-RESET-80-AMP/ (http://www.waytekwire.com/item/46913/HI-AMP-AUTO-RESET-80-AMP/)
They have a similar 100 amp breaker, too, if you decide to go that route.
Waytek will also have a 20 amp panel mount breaker to replace that corroded one below.
BTW, you might be able to find one at NAPA or you might try a semi-truck parts house. Another option might be to call one of the local charter companies and
ask them if they might have one they'd sell to you.
Thanks again Gumpy!
yea I have looked around the internet for one and can't find it either. Of course there are lots of types of breakers out there, just haven't found a direct fit, therefore I may have to do some modifying like you said. I'm wondering if that 130 amp breaker right next to it is even being used? It says it's going to a blower? Isn't that the old air conditioner and heater that would have been in it back in the day? Wondering if I could possibly use that one?
No. Don't do that. The breaker is there to protect the wire in the event of a short. The breaker must be sized less than the maximum current carrying capacity of
the wire. The wire on the 90 amp breaker is a #1 and is rated at about 125 amps in an enclosed space. That other breaker exceeds that capacity and so would not
protect the wire in a short.
The wire on that other breaker is a #2, which has a much higher current rating. Interesting that it's still connected, though, if your blowers have been removed.
You might want to trace it and see where it goes and what was done on the other end of it when the blowers were removed. Obviously it's still hot!
If it's not being used, you could eliminate the bus bar alltogether with one of the high current breakers like in the link I sent. Just attach the battery cable to
one post and the feed to the front panel to the other and remove the other breaker and cable completely.
When you buy the breaker, make sure the posts are the right size for you wire. Changing the lugs is a real PITA. I think the lug on those cables has a hole larger than 1/4" if I recall.
Don and Cary