Electrical Problem

[manfromwahoo]

Thanks for all of the input. I have another question. Does disconnecting the battery disconnect next to the floor pedals have the same effect as disconnecting the negative battery terminal from the actual engine battery beneath the pilot's floor? i.e. supposedly reset the system?

[TJLee089]

Yes. This is the connection for the negative battery cable.

[Klipstr]

If you don't have anything directly connected to the battery positive. Scarecrow is working an issue where maybe that happened. As he told us when we picked up his rig in SLC the disconnect was engaged but the chassis battery was still quite dead. He suspects the installation of the new radio unit might be the culprit as he already replaced the chassis battery once. I know from my own experience that disconnecting at the gas pedal resulted in exactly the result wahoo expects. If you haven't had anything new installed on can assume the disconnect actually disconnects!

[TJLee089]

Not sure exactly what you mean, but if the battery negative is truly disconnected, there can be no current and it doesn't matter if anything is directly connected to the battery positive.

Originally Posted by Klipstr

If you don't have anything directly connected to the battery positive. Scarecrow is working an issue where maybe that happened. As he told us when we picked up his rig in SLC the disconnect was engaged but the chassis battery was still quite dead. He suspects the installation of the new radio unit might be the culprit as he already replaced the chassis battery once. I know from my own experience that disconnecting at the gas pedal resulted in exactly the result wahoo expects. If you haven't had anything new installed on can assume the disconnect actually disconnects!

[Klipstr]

Yes, that is correct. What I meant was that if you use the positive disconnect by the gas pedal in the cab you may or may not get all the loads disconnected. If you disconnect the negative at the battery you most certainly get all the loads disconnected. Sorry for the confusion.

[mikeme]

Originally Posted by Klipstr

Yes, that is correct. What I meant was that if you use the positive disconnect by the gas pedal in the cab you may or may not get all the loads disconnected. If you disconnect the negative at the battery you most certainly get all the loads disconnected. Sorry for the confusion.

On the Sprinter, the disconnect by the accelerator is directly connected to (and only to) the negative terminal of the battery. In fact, if you pull the floor cover and access the battery, you can disconnect the negative terminal from the battery and see that the the disconnect wire is only a foot and half long and goes only to the negative terminal of the battery.

[TJLee089]

As Mikeme implied, there is no need to ever disconnect the negative at the battery unless an additional negative lead has been added there.

Originally Posted by Klipstr

Yes, that is correct. What I meant was that if you use the positive disconnect by the gas pedal in the cab you may or may not get all the loads disconnected. If you disconnect the negative at the battery you most certainly get all the loads disconnected. Sorry for the confusion.

[manfromwahoo]

Problem solved. As it turned out, a new multimeter showed me that my brand new 1.5 amp Schumacher charger/Maintainer was defective. So, I returned the defective 1.5 amp and bought a 3 amp Schumacher. Hooked it up to the contacts under the hood and 15 hrs later the ignition freed up. Finished it off through the cigarette lighter.
Thank you all for your help. A real learning experience for me.

[woundedpig]

Originally Posted by manfromwahoo

A real learning experience for me.

Multimeters are nice to have. We carry one on the road. Great for troubleshooting, making sense of things, not just from voltage measurements. I have been able to diagnosis blown fuses that did not look blown and an AC breaker that had failed.

[woodywesty]

Originally Posted by manfromwahoo

We have a 2019 Unity IB with a 2018 MB chassis. Less than 5,000 miles on it. And we have an electrical problem. We have been parked for about 3 weeks. We used the dash radio a few times and I think that we could have wore down the engine battery. Just before we noticed that there was a problem we had issues with our side entry dead-bolt (sticking) not retracting when using the key fobs. Suddenly, we had no seize noise when key inserted into ignition and the key will not turn in it, the key fobs won't work at all, and all dash lites are out. Upon the advice of LTV warranty service I charged the battery using a 1.5 amp trickle charger. The new charger only took about 5 hours to bring the battery up and then it indicated that it was in float mode. I left it on for another 20 hours and it was still in float mode. The key still wouldn't turn in the ignition. I'm confident that the charger did it's job but I haven't opened up the floor to check out the battery. ???

The engine battery is a substantial battery compared to a regular gas powered auto battery. Diesels need power to start them up. I can't imagine a trickle charger being able to charge a dead battery of that size. Best option is to get the engine battery charged normally at a slow rate. Read the manual about jump starting your battery. Lots of very expensive micro electronics under that hood. In the future I would not use the Mercedes radio while camping and use the entertainment center instead. We hooked up a Sirius unit to the entertainment center and use the camper batteries and solar panels to listen to music etc. Good luck.

Bob