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Old 04-26-2014, 07:06 PM   #1
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Wiring to genset

On my 2001 Marlin, I need some help with where the wiring runs from the back to front. I am trying to solve a problem with starting the Generac gen. It will turn but will not catch and start. It is like it doesn't have enough amps to turn it over all the way. I have cleaned ALL connections, both + and -. My Start Boost that should link both battery banks (2 12v and 4 6v) does not seem to do anything when pressed. This is a Spartan chassis.

The Battery Control Center may be the issue with the boost switch. Not sure yet. So I want to try to bypass the current setup and try starting the gen from the chassis batteries to see if it will have enough amps to start. Although the Xantrex panel shows the batts. to be fully charged, I am not convinced they are. I will try to solve this too.

Does anyone know how the wiring is connected? The Marlin is very likely the same as the Tradewinds especially between 2000 and 2004 I suspect. It is really hard to trace what goes where as nothing is labeled and of course no wiring diagram.

I want to move the cable from the house batts to the engine batts. Not sure which cable does it.

I don't know why the gen. starting batteries would be off the house anyway. The CCA are always lower while the AH is high. Need CCA to start a larger engine like a 7.5KW gen. Seems that the chassis batts should be the power source for the genset anyway.

Any help will be appreciated.

John
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Old 04-27-2014, 03:32 AM   #2
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John, you're just going to have to pull one at a time and keep trying to start it until you find it's connection. Have you tried powering the genset with a separate battery using jumper cables right at the genset itself? It's possible the starter or wiring within the genset has issues.
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Old 04-27-2014, 07:34 AM   #3
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Oh boy.....John......where do I start! I likely have the same set-up as you do on the genny wiring......and I have had the same "no start issues", off and on, for the last 4 years. I FINALLY have solved the issue, not perfect but satisfactory because I think the genny starter is underpowered from the get-go, by thoroughly cleaning the ground connection to the chassis from the house battery bank. On my coach this very important ground is located back behind the battery bank, chassis side, on the side of the chassis rail. It is a bolt welded to the chassis and it was rusted and the nut was not that tight. I cleaned it the best I could without damaging the threads and then I made a 2nd ground with a new bolt, ground the paint and coating off the chassis rail down to bright metal, and I connected it to the battery bank NEG with a short black 6 gauge battery cable that I bought....I also used a conductive dielectric grease on all connections.

The problem with the original set-up is the long distance from the genny to the Battery Bank, about 25 feet. Additionally this cable goes through at least 6 additional contacts/junctions, all subject to corrosion/resistive connections, before it gets to the input side of the genny starter relay, including the 12V battery disconnect relay. I have measured the voltage at the input post of the starter relay and it drops to about 7.5 VDC under load, 5 volts is lost in the resistance of the long cable run and the junctions/connections.......and that is why the genny barely turns over.

As already suggested, you can use your car battery and jump right to the post on the input side of the starter relay with a good ground to the chassis, to see if there are problems with connections on the other side of the starter relay or if it's the starter itself. Rook
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Old 04-27-2014, 09:02 AM   #4
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Originally Posted by Rook View Post
Oh boy.....John......where do I start! I likely have the same set-up as you do on the genny wiring......and I have had the same "no start issues", off and on, for the last 4 years. I FINALLY have solved the issue, not perfect but satisfactory because I think the genny starter is underpowered from the get-go, by thoroughly cleaning the ground connection to the chassis from the house battery bank. On my coach this very important ground is located back behind the battery bank, chassis side, on the side of the chassis rail. It is a bolt welded to the chassis and it was rusted and the nut was not that tight. I cleaned it the best I could without damaging the threads and then I made a 2nd ground with a new bolt, ground the paint and coating off the chassis rail down to bright metal, and I connected it to the battery bank NEG with a short black 6 gauge battery cable that I bought....I also used a conductive dielectric grease on all connections.

The problem with the original set-up is the long distance from the genny to the Battery Bank, about 25 feet. Additionally this cable goes through at least 6 additional contacts/junctions, all subject to corrosion/resistive connections, before it gets to the input side of the genny starter relay, including the 12V battery disconnect relay. I have measured the voltage at the input post of the starter relay and it drops to about 7.5 VDC under load, 5 volts is lost in the resistance of the long cable run and the junctions/connections.......and that is why the genny barely turns over.

As already suggested, you can use your car battery and jump right to the post on the input side of the starter relay with a good ground to the chassis, to see if there are problems with connections on the other side of the starter relay or if it's the starter itself. Rook
Thanks for the feedback Rook.

How hard was it to find those contacts/junctions you mentioned? Are you including those in the Battery Distribution Center? I assumed there was a single cable run from the battery area to the genset. If that is not so, then I have to find where there are connections and clean those. How did you trace the cable under the chassis? Mine will be very difficult to follow and get to in addition to being encased in the black plastic corrugated loom. They all look alike underneath in the loom.

I will try the jump start from my car when I can rig that up. I assume that the car batt. will give power to the panel preheat switch etc. or does it matter? It may get its power from the chassis batteries. Should work either way.

I will also look into the main ground you mentioned. There is a lot of stuff under this chassis that I often don't know what it is or what it does, etc. All of it seems a little or a lot hard to get to....

Does your Start Boost switch work? Have you tried it to start the genset? I was told it connects the 2 battery banks regardless of trying to start the engine or the genset. Mine does nothing which is another issue.

John
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Old 04-27-2014, 12:09 PM   #5
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John, on my coach, in the rear bay passenger side, there is a 12 VDC distribution panel with a lot of relays and fuses, mounted on the rear wall above the Inverter. Here is a schematic:

12v,120v power system all models.pdf There are other useful electrical schematics in this file, as well.

Referring to the schematic, there is a large terminal labeled "generator and Jacks", lower right corner, one of the 6 gauge wires connected there goes directly to the input side of the gen starter relay (the 25 ft run) the other one goes to the jack pump. Backtracking from that connection on the panel, the connection goes back through a 150amp ckt bkr., to one side of the battery disconnect relay, from there through the relay contacts, (normally closed), to the other side, then connects to a junction on one side of the battery boost relay and from there finally to the + terminal on the house battery bank. That is several junctions and relay contacts. The 150 amp ckt bkr, the battery disconnect relay and the battery boost relay are all on the backside of the 12V Distribution panel and cannot be seen from the front...... you can feel them with your hand.

Sounds like you might have a bad battery boost relay. But even if it is OK, the 12 volts has to go through all those connections, relay contacts and ckt bkr, plus the 25 feet of cable before it gets to the input side of the gen starter relay. Then it has to go through the relay contacts, the connection on the other side, a short cable run to a connection directly on the starter. A lot of opportunity for corroded connections/contacts and long cable for loss of a few volts. However, I'm betting that resistive ground connections are most of your problem. Rook
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Old 04-27-2014, 02:10 PM   #6
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Quote:
Originally Posted by Rook View Post
John, on my coach, in the rear bay passenger side, there is a 12 VDC distribution panel with a lot of relays and fuses, mounted on the rear wall above the Inverter. Here is a schematic:

Attachment 61487 There are other useful electrical schematics in this file, as well.

Referring to the schematic, there is a large terminal labeled "generator and Jacks", lower right corner, one of the 6 gauge wires connected there goes directly to the input side of the gen starter relay (the 25 ft run) the other one goes to the jack pump. Backtracking from that connection on the panel, the connection goes back through a 150amp ckt bkr., to one side of the battery disconnect relay, from there through the relay contacts, (normally closed), to the other side, then connects to a junction on one side of the battery boost relay and from there finally to the + terminal on the house battery bank. That is several junctions and relay contacts. The 150 amp ckt bkr, the battery disconnect relay and the battery boost relay are all on the backside of the 12V Distribution panel and cannot be seen from the front...... you can feel them with your hand.

Sounds like you might have a bad battery boost relay. But even if it is OK, the 12 volts has to go through all those connections, relay contacts and ckt bkr, plus the 25 feet of cable before it gets to the input side of the gen starter relay. Then it has to go through the relay contacts, the connection on the other side, a short cable run to a connection directly on the starter. A lot of opportunity for corroded connections/contacts and long cable for loss of a few volts. However, I'm betting that resistive ground connections are most of your problem. Rook
Rook, Thanks for the schematics. I did not have any. My next step is to redo the chassis ground.
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Old 04-27-2014, 04:09 PM   #7
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John:
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Somebody above had the same suggestion as my marine diesel friend. Try starting it with another battery and short cables, or use your car and jumper cables before you do anything else. That will isolate the problem one way or the other. If the chassis harness is not the problem I wouldn't mess with it.
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Old 04-27-2014, 08:13 PM   #8
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John:
The best way to fix your problem is for you to come out here and I will help you!
The space right in front of me will be vacant after the 4th of May. You can move right in...
Somebody above had the same suggestion as my marine diesel friend. Try starting it with another battery and short cables, or use your car and jumper cables before you do anything else. That will isolate the problem one way or the other. If the chassis harness is not the problem I wouldn't mess with it.
Mike
Watch out Mike I may be on my way. LOL

I plan to try the car jumper as soon I feel better and can get under the rig to hook it up. Have you ever had trouble starting the genset? Does it always kick off as soon as you try to crank it?

John
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Old 04-28-2014, 06:08 AM   #9
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John, this is an alternative to the car battery and cables. Since you have to get down under to connect it. I have one of these and I use it to power my aux brake for my toad. No more DEAD car battery. Rook

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Old 04-29-2014, 02:45 PM   #10
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Update

I tried starting the genset from my car battery while engine running. It would only try to turn over but still would not turn enough to start up. It only moves the flywheel a little. Basically the same problem I have when using the normal house batteries.

Not sure what that means except most of the problem is now with the genset. Last year I had about the same problem and did everything except take the genset out (it's bolted on, no slide). I was able with much effort to take a bottom panel off and had to remove the water hose to get some access to the starter. I cleaned all contact points I could reach. It did start most of the time after that. I don't know if I will tackle that again, laying on my back with a good chunk of 26000 lbs over me.

Any suggestions?

John
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Old 04-29-2014, 05:00 PM   #11
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If you connected the ground from your car battery somewhere on the chassis, then it still could be that the Genset has a bad ground to the chassis and/or where it connects to the Genset block. Rook
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Old 04-29-2014, 05:39 PM   #12
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If you connected the ground from your car battery somewhere on the chassis, then it still could be that the Genset has a bad ground to the chassis and/or where it connects to the Genset block. Rook
Rook, you are right. I'm not convinced that I'm getting good ground from the genset internal connection to the external stud bolt that goes to the frame rail. Last year when I worked on it I'm not sure what I did to make it work except to clean connections. It was still hard to crank even then.

John
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Old 04-29-2014, 10:09 PM   #13
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It would also make a difference as to what size battery you were trying to jump it from as some of them are pretty weak,even with the engine. I had an Excursion 7.3 PSD and had to have it jumped a couple of times and it had to be done by a tow truck. I did buy one of those 75amp jumpers and that would do the job. I'm gonna try using that to jump the gennie.
My question is.... Should I just hook it up to the wires with them still connected to the house batteries, OORRR, should I disconnect those wires at the gennie????
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Old 04-30-2014, 02:23 AM   #14
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Leave the house batteries connected....they will supply some additional power. Rook
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