Bad battery disconnect switch

dengraham · 07-30-2011, 08:18 PM

Has anyone experienced a bad chassis battery disconnect switch. Mine broke when I parked the motor home after a 1,900 mile trip in our garage. The timing was good as we just got home. I never used the switch and was surprised the plastic just broke and the dial (on/off) fell off. Then you discover you have no comparment remotes, no levelers, no slides, no compartment lights, no engine, etc. I ordered a new one but I have not seen anyone else talk about the problem?? I guess you are supposed to turn it off if you store the motor home for over a month but we store it connected to shore power so I have never used it.

dengraham · 08-11-2011, 10:13 PM

Well, I replaced the battery disconnect switch but now the motor home will not start. Actually, it will not turn over. For some strange reason I am not getting sufficient voltage to the starter relay that sends 12 volts to the starter selenoid which then starts the starter. I am only receiving 8.6 volts at the starter relay (which typically means a bad ground or a bad relay). Now the challenge will be to find where and why I am losing the voltage?? I have disdovered several fuses (all good so far) and at least three additional relays but I still cannot figure out why I am not getting sufficient power to the starter relay?? I guess no one else has run into this problem as Winnegabo cannot seem to help and Freightliner Service can only send me the schematics and let me do all the tracking. It would be great if I could just find a bad fuse but so far no luck. Has anyone out there had to deal with the lose of power to their starter?? I did jump the starter selenoid and got the engine started but, get this, as soon as I turned on the headlights the engine stopped..... which would normally mean a bad battery but how did I have power to start the engine but not enough to run it with the lights on?? Anyone out there that can help me??

garym114 · 08-11-2011, 11:30 PM

What is the voltage going in and out of the disconnect switch? Start there and go to the starter solenoid, component by component, connection by connection.

dengraham · 08-12-2011, 06:29 AM

Hi Gary,
I have 13 volts on the "big" wires but only 8.6 volts coming into the relay on the "small" wires. That was not enough so I disconnected it and gave it 12 volts to confirm the switch (and battery selenoid and starter) would work if the switch was receiving the proper voltage but I am having trouble figuring out which wires to check at the neutral start relay and the starter lockout relay. I checked all the fuses and switched the relays (as they are the same) but I don't know which wire to test. I am told the wires are numbered but I have not figured them out yet. On the schematic it looks like the number for the neutral start is 15 (PK) and for the starter lockout is 15 # 1004 (PK) 1 but I don't know which of those numbers is the wire size and which is the cable number. What does (PK) mean??

dengraham · 08-12-2011, 06:51 AM

I'm sorry Gary, you asked at the disconnect switch and I was talking about at the engine harness. My problem is trying to figure out all the connections inbetween. The wire from the disconnect switch travels to the dash harness, the body builder power, and a fuse/relay center. Three directions all at once. So, I need to try to follow all of them, I guess

Nuge · 08-12-2011, 07:07 AM

Burned and pitted contacts in your solenoid will cause a voltage drop and a starter going bad will also cause the symptoms you describe. What's throwing me off is the issue with the lights; that sounds more like a bad battery or possibly grounded light wires. I would start cleaning all the battery connections at the battery and the ground. It is said that if your battery has been drained all the way down 3 or more times you can no longer depend on it.

dengraham · 08-15-2011, 06:50 PM

Thanks Nuge,
I have decided I need to find someone that knows were on the coach is the location of the connection from Freightliner to Winnebago for the rear of the coach. In other words, I want to isolate the Freightliner 12 volt harness from the Winnebago connections to the brake lights, running lights, etc. There is a plug someplace along the chassis at the rear of the motor home but I have not been able to find it. If I can separate the Winnebago voltage from the Freightliner then I can figure out were the short is. Anyone out there had their rear shell taken off? They would need to disconnect the lighting harness from the chassis but I just can't find it... so far.

spotknot · 08-15-2011, 08:01 PM

if your motor quites when you turn on the lights,9 times out of 10 its a bad ground...

Dave78Chief · 08-16-2011, 10:05 AM

Based on the Winnebago Wiring Installation diagram, the cable you are looking for is routed to the front side of the engine at centerline.
http://www.winnebagoind.com/diagram/...ire_158642.pdf
Main chassis drop just to the left of the AB circle on right side of pdf page 2

Winnebago wiring and installation data for a 2007 Vectra 40TD: Table of Contents

I do not have access to the Freightliner drawings so I cannot help you much.

Dave

dengraham · 08-16-2011, 08:00 PM

Thanks Dave,
I just found it. Pulled it apart and discovered all my lights went out. That is a good thing as they were being powered by 8 volts from an unknown source. BUT, more important with the ignition switch turned on my transmission went from the neutral position to "no signal" position which is a pair of stars.... I think this means I either have no connection, the tranny ecm is blank, or I have blown a fuse. So, to date I have talked to Cummins who said if the engine starts then there is nothing wrong on their side of the house, Freightliner who said the problem sounds like a short someplace, a local Freightliner repair shop that didn't want to touch it because of the extended warranty, a Oasis Freightliner shop that said if the rear lights are shorted then they first diagnois the Freightliner lines and then they will call Winnebago to find out were their lines go, and then Winnebago who wisely told me to hunt for the disconnect for the rear lights. Tomorrow, I get to call Allison and ask how to figure out what is wrong. I don't know of any Allison fuse but I have heard of them losing their memory and needing to be reprogrammed. I thought they would re-set themselves when you disconnected the batteries but if the brain is dead I guess it cannot reset itself. If this is the case it finally is starting to make sense because the last thing I remember doing when I turned off the motorhome was press the neutral button. That is when the battery disconnect switch broke, so maybe there was a spark or surge or something and the Allison is really not in neutral (or cannot send a signal that it is in neutral) and that is why I can't get any power from the neutral switch to the starter relay. Anyone else had any problems with the Allison brain??? I'm looking for a little brain power here....

Dave78Chief · 08-17-2011, 01:45 PM

Dennis,
Don't get into the overthinking it trap. The 8VDC and the shut off when the headlights were turned on indicate you have a bad connection some place. When you turned the headlights on that most likely created a large amperage draw. With a bad connection, that would result in a large voltage drop across the bad connection. I suspect that resulted in to low of a voltage for the engine electroinics to keep working and shut down. While it is obviously difficult to trace the signals through different Mfg drawings, it is most likely what you will have to do in the end. It could be a case that the Allison brains cannot send out the proper indication when the operating voltage is only 8VDC.

Dave

dengraham · 08-22-2011, 08:49 PM

Dave and Spotknot, You both keep telling me to find the bad connection. The towtruck driver said it has to be a ground wire. We checked everyone on the batteries. One of the little ones on the batteries was broke but still touching (actually it was held together by the shrink wrap so you could not see the break). He told me to leave the key on and he kept pressing all the ground wires until the lights went out at the back of the motor home. Then, it started right up. I must have broke the wire myself when I disconnected the battery wires to replace the battery disconnect switch. So I created the problem myself. It did finally explain how it was somehow related to the bad disconnect switch. Mystery solved. Dummy identified.

bluepill · 08-22-2011, 09:03 PM

I herby award you one gold star for patience, and one silver star as a deputy assistant to Mr. Murphy.

"It's the little stuff that can make ya crazy"

VectraDon · 08-27-2011, 03:33 PM

Try this. Have someone turn on the battery disconnect switch at the same time as you start the engine using the battery boost switch. It works on my Vectra. Something about flipping the diode ??

dengraham · 08-28-2011, 11:03 PM

For the benefit of someone else running into a "no start" problem. Here aer some photos. Photo one shows what looks like a good connector but the metal is really only held together by the rubber shrink wrap.
Photo 2 shows the broken connection.
Photo 3 shows the small wire in question at the battery ground side.

Bug512 · 08-29-2011, 07:34 PM

Glad that you have resolved your problem.

spotknot · 08-31-2011, 07:27 PM

way too go glad you kept your sanity. good luck in your future travels,an god bless.

VectraDon · 08-31-2011, 07:41 PM

I've had the problem of the engine dying when the lights or windshield wipers were turned on. It turned out to be the 300 amp circuit breaker found on the driverside frame rail, next to the transmission. It's probably corroded.