2008 Winnebago Destination not starting

[ShawnB213]

Originally Posted by Skip426

Shawn : ECMs , engine and trans , will do strange things below 10 volts .

I once spent entirely too much time on a vehicle that would come up with fault codes ; about battery voltage lost . Only to find out how sensitive the ECM was. '
Engine cranking would drop battery voltage supply to the ECM below 9.8 volts momentarily and set the code . Old battery load test spec; was to hold 9.6 volts or above for 15 seconds under a 400 amp load ; and the battery passed the load test .
But the code still set .

EDIT : Pick up a can of electrical contact cleaner , and spray any connector you take apart to examine.

One of the first things I did was take the chassis battery and the starter to the auto parts store to have them both tested. The battery was practically brand new and they said it tested good. They told me the starter was bad, even though it worked fine the day before and wasn’t even getting a signal for it to crank. I ended buying a new starter (probably a waste of $200).
That Trombetta solenoid- is that something that can intermittently go bad? Could there be a bad connection to it?

[ShawnB213]

Originally Posted by Skip426

Shawn : ECMs , engine and trans , will do strange things below 10 volts .

I once spent entirely too much time on a vehicle that would come up with fault codes ; about battery voltage lost . Only to find out how sensitive the ECM was. '
Engine cranking would drop battery voltage supply to the ECM below 9.8 volts momentarily and set the code . Old battery load test spec; was to hold 9.6 volts or above for 15 seconds under a 400 amp load ; and the battery passed the load test .
But the code still set .

EDIT : Pick up a can of electrical contact cleaner , and spray any connector you take apart to examine.

I will check the the voltage again this weekend. One thing to note is that the RV started a few more times after that (with no power pack on it).

[ShawnB213]

Originally Posted by Lash

Thanks for the quick update back. The diagram you attached is for the Trombetta relay which is a notorious "bad actor". It is used to isolate the chassis battery from the house battery so that the house batteries cannot drag down the chassis battery if the house batteries get below a certain voltage. The Trombetta will chatter if the voltage from the battery is on the ragged edge.

If it were me, I would take the chassis battery to auto parts store and have it load tested. If the coach started with a battery pack, then most likely all the hardware is functioning as it should. Maybe the chassis battery cannot take a load when you try to start the coach. At least getting it tested will take it out of the questionable piece.

Best regards

I think I hit quote on the same response twice when I was trying to respond separately. I think you can figure out which post is for which- though they both have strong similarities.

[MrMark52]

Originally Posted by ShawnB213

One of the first things I did was take the chassis battery and the starter to the auto parts store to have them both tested. The battery was practically brand new and they said it tested good. They told me the starter was bad, even though it worked fine the day before and wasn’t even getting a signal for it to crank. I ended buying a new starter (probably a waste of $200).
That Trombetta solenoid- is that something that can intermittently go bad? Could there be a bad connection to it?

Shawn - the way a Trombetta solenoid is made they can get carbonized patches on either the moving disc or the stationary poles that the battery cables connect to. All of this is internal to the relay.
And, as they age and go through numerous cycles, the armature sleeve can wear and prevent the disc from making a solid contact with the poles, causing further carbonization of the disc (assuming some contact has been made).
And it explains intermittent operation.
Trombetta’s of long ago (think of the old Ford firewall mounted starter solenoids) were more robust than those made more recently.

[ShawnB213]

Originally Posted by MrMark52

Shawn - the way a Trombetta solenoid is made they can get carbonized patches on either the moving disc or the stationary poles that the battery cables connect to. All of this is internal to the relay.
And, as they age and go through numerous cycles, the armature sleeve can wear and prevent the disc from making a solid contact with the poles, causing further carbonization of the disc (assuming some contact has been made).
And it explains intermittent operation.
Trombetta’s of long ago (think of the old Ford firewall mounted starter solenoids) were more robust than those made more recently.

Thank you for that. That would be an easy part to replace. Would this explain the comm failure codes?

[MrMark52]

Originally Posted by ShawnB213

Thank you for that. That would be an easy part to replace. Would this explain the comm failure codes?

Possible, but probably not.

The Trombetta is only used when high current, short term loads need to be switched, like a starter. They are also typically used for tying the coach and chassis batteries together momentarily to get the chassis engine started, or the generator started (which in turn, once started will hopefully charge the chassis batteries enough that they can then get the engine started.

I’m more inclined to think your other issues are ground bonding issues. Start at your battery grounds at the batteries, then where they attach to the chassis. Everywhere you see a stud welded to the chassis that have wires under them, check for their being tight, then loosen, disassemble, look for signs of corrosion, reassemble and tighten everything back up.

And it could also be loose connectors to your ECM/TCM and other places where multi-pin connectors are involved - like your transmission selector panel or at the transmission.

[ShawnB213]

Got it. I will begin the process on Sunday and post an update. Thank you, again.

[Lash]

After reading your previous posts about the chassis battery being almost new, would lean more towards a ground corrosion issue. This would explain the comm failure issue as this fault could come when there is an issue between the TCM (Transmission Control Module) and the PCM (Power Control Module) based on the Workhorse Electrical Schematics.

Since this problem is intermittent, would agree with the previous commentor that the issue may be with the grounds associated with the front part of the coach since a lot of these alarms come from that area.

Cleaning all grounds is just grunt work and would take that issue off the table. Workhorse drawing show all the ground connections and makes less of a job on tracking them all down. Navistar has posted electrical schematics for R26 chassis which is what you have and there are a few pages dedicated to ground connections.

Best regards

[ShawnB213]

I will make sure to do the grunt work on the grounds on Sunday. Hopefully I will be able to get it all done before I have to go back to work for the week. I’ll send an update.