That was BOB-00's coach you were trying to start. ;)
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That was BOB-00's coach you were trying to start. ;)
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They are both sitting side by side out front on their lot. They seem to be leaning towards each other. We need a dual sale on this deal because one would be very lonely without the other !
To; Jon John, Joe, Tom, all the Jims, and everyone else that helped me solve this problem. It was one battery cable that caused all this starting problem. The center battery of the rear three had the - cable going to the right rear battery - instead of going to the negative on the single forward battery. I am now sure that the 1st company that tried to jump the batteries did this but it could have been the second. I tried watching them but it is a bit difficult getting two people into that space. I also went inside the house and the cab while they were working. Still no excuse for not double checking their work. Yesterday it got 2 degrees above freezing and the snow slowed to a shower so I went out and took pictures of the batteries and of the battery schematic on the door (thanks for pointing that out also) and then retreated to the house and my computer. Upon examination it became very clear that one cable was misplaced. Since it was 15 degrees this morning I waited until the temp got up to 33 and went out and made the change. I checked for the 24V at the shut-off switch and knew it would be OK. Needless to say the coach fired right up.Quote:
Originally Posted by Jon Wehrenberg
My only issue right now is why the yellow wire at the negative pole on the inside rear battery sparks when I attach it. It does that regardless of the position of of the shut-off switches. I am going to see if I can find something that identifies that wire and where it goes after leaving the battery. See attached pic. The unattached yellow wire is at the top right of the picture and the offending cable is on the bottom right, before it was moved.
I want to sincerely apologize to all, especially Jon, who spent so many hours helping me solve something that should have been obvious. :oThis was real stupidity on my part and I caused a lot of work that shouldn't have been necessary. The good thing, for me, is that you great POGers helped me find the problem. I guess I thought it couldn't be the cables since they seemed to fit like a jig puzzle. Wrong!! Thanks, Darl:)
Darl, for what it's worth, my Liberty has the very same arrangement with regard to the yellow wires.
Mine were seriously deteriorated, and I have replaced the ends with new connectors.
Glad to hear, even though you went through a lot, that it turned out to be an easy fix after all.
In the future, though, you might pick a better season to play with this stuff...
Paul, thanks for the info. Do you know the origin of these yellow wires, specifically the one attached to the negative post on the third battery? (inside, nearest to frame ground)
Mine arcs when I attach it to the post. I haven't been able to get an amp draw reading since my tester quit :mad:but it is not a dead ground, just a slight arc.
I'll take your advice about working on this stuff in better weather. Thanks!
Darl,
On mine, the mysterious yellow wires disappear into what appears to be original equipment wire looms. I was told by Liberty that they power the engine and transmission computers. There may also be something else that is powered by them.
On mine, when I took them off and re-attached them, there was a small "spark", which I kind of expected. This, as far as I know, is considered "normal". I have an appointment next week at Liberty Coach and hopefully I'll get some more information as to their purpose.
The reason I had mine apart in the first place was that my chassis batteries would drain down while parked, and I needed to charge them. I have since installed a 12/24 volt battery charger in the battery bay to resolve this issue. Truk can give you guidance if this is also a concern of yours, since he guided me through the process and I'm very happy with the outcome.
According to the Prevost wiring diagram #D060873, page #1 those wires go to DDEC power junction #10 in the rear box, and the ECM power connector for the 12 V wires on the negative terminal, and to the transmission feed via CB83, CB19, CB20, CB21 for DDEC3 feed, and junction #5 for transmission feed on the positive side 12 V wires.
Great news about the success Darl. FWIW when we had to be towed because of the fire in our previous bus I sent the first tow driver away because he did not convince me he knew what he is doing. I think if anybody has a problem and the service tech does not instill confidence we are better off to send them on the way.
I am in the process of doing an article that should help with a basic understanding of the coach electrical systems. With help from Jeff (as in JPJ) and Ben of Parliament Coach the article is being done in a question and answer format. As we were discussing chassis batteries Ben revealed something I have never heard before, nor have I ever seen it in a service bulletin, or in a shop manual. The information Ben provided goes right to the heart of two of the very important threads recently covered here.
As I learned (to my chagrin) and posted previously Prevost does wire from the batteries directly to the rear electrical box without going through the chassis battery disconnect switches. I now think I fully understand why, and I also understand why some coaches experience drained chassis batteries and require a battery charger or maintainer.
First a reminder of what wires bypass the battery disconnect switches. Those wires such as on Paul's, or Truks or any coach in that vintage power circuit breakers 19, 20, and 21 in the rear electrical box. Two relate to the DDEC and one relates to the transmission computer.
Ben indicated that they experienced random instances of dead chassis batteries on coaches being converted and found that it relates to how Detroit Diesel set up their DDEC and/or engine. On some, (Ben estimates 50%) of the coaches the power from the batteries is going to the fuel injector solenoids. On others the circuit was open. This explains why some of us could go months and the batteries were still charged, yet others of us would have dead batteries if an auxiliary charger was not used. Remember, these circuits completely bypass the main battery disconnect and the 12 volt disconnect.
On coaches with this characteristic the battery drain can be stopped by tripping the DDEC circuit breakers. The downside to doing this in addition to it being a pain to have to do, is that some memory logging in the DDEC will be lost, and some items in the volatile memory are erased.
So we can all breathe a little easier thanks to Ben because a problem we here could not quite get our arms around, we now have a logical explanation for why some of us need an auxiliary charger and why those with the problem of battery drainage see that spark when reconnecting the DDEC wires to the battery.
Jon, thanks so much for doing this research! I think this may have been what caused my battery problem rather that the ignition being in the accessory position. I am going to install an auxiliary battery charger for sure. What will happen if the circuit breakers are tripped? I was considering the installation of a toggle switch in the line from the battery to the DDEC. Right now I have that wire disconnected from the terminal to avoid having my batteries discharge. Now I am concerned that I may have caused damage to the computer. When I had my electrical problem the batteries were disconnected for over a week and were dead prior to that. Did your research give you information about the consequences if items in the memory logging or the volatile memory are erased? I didn't have any problem running the engine but I didn't drive the coach after finally getting it started. Maybe I should connect my Silverleaf code reader prior to driving the coach.
Again Jon, thanks for all you do!:D
Darl,
You may wish to discuss this with Prevost engineers (this is beyond service center techs I think) or Detroit Diesel experts, but as Ben explained the load can be removed by tripping the CBs and the only issue is the loss of some memory items. If you have had any codes as indicated by the red or amber warning lights on the dash you may not wish to erase them until a tech can read them, but otherwise I did not get a sense from Ben that there were any other concerns.
Removing power from all of this should do no damage whatsoever because removing power is what happens when you replace batteries or remove them for testing or service.
I see a greater concern over damage if someone connects those circuits to 24 volts.