Mercedes Sprinter/Thor Synergy starting problems y

[Southboun]

Hi folks, posting this for my rv park neighbours, who are two elderly ladies. They bought this used rig from camping world a couple months ago. Went to start it this morning and nothing. The key barely turns in the ignition. All doors were shut and foot on brake. My first thought was the key battery was dead, but using the second key produces same results. Checked the batteries which are solar charged and both at 14V. Bill of sale only lists the coach as 2020 Synergy, doesn't list year of chassis.

This is foreign territory to me, so looking for experienced input. They have a call I to Good Sam RSS but, hoping to save them some bucks.

Thanks for any thoughts.

Cheers
Keith

[Southboun]

Meant to add that neither key fob door locks are responsive. Hard to believe both fob baths wrapped out at same time.

Keith

[jacwjames]

Force the steering wheel in both directions while turning the key and see if that helps.

[Paul_D]

Check the Sprinter chassis battery voltage. It's mounted below the drivers floor, but there is a ground connection and battery positive connection under the hood. Open the hood and on the drivers side fender there will be a brass post - the ground. Then look at the right side of the air cleaner box for a red knob like thing. push it in and turn to access the positive terminal.

That will be the chassis battery. There's one other thing to check. In the drivers footwell, to the right of the accelerator pedal, is a ground connector.
Its there so you can disconnect the battery when storing the van. Make sure thats on tight.

If you turn off a Sprinter and don't open and close a front door, several systems stay energized. This could drain the battery. So if you stop, turn off the Sprinter than walk into the house, without opening and closing the Sprinter doors, you might kill the battery.

[Southboun]

Hi folks, thanks for the replies. Both house and chassis batteries are in the passenger side floor and check at 14V. I did reef on the steering wheel as you suggested but nada. Manual indicates a locked wheel or locked engagement system, whatever that is. I'll check under the hood. They ran this about a month ago and did t do anything different. I did notice the steering wheel is cranked to the left which may have locked things up.

Keith

[Paul_D]

One other possibility - Did they turn off the battery disconnect switch and not turn it back on?

[bigb56]

Originally Posted by Southboun

Hi folks, thanks for the replies. Both house and chassis batteries are in the passenger side floor and check at 14V. I did reef on the steering wheel as you suggested but nada. Manual indicates a locked wheel or locked engagement system, whatever that is. I'll check under the hood. They ran this about a month ago and did t do anything different. I did notice the steering wheel is cranked to the left which may have locked things up.

Keith

If I understand correctly it hasn't run for a month? The Sprinter battery can easily go flat in a month of non-use, in fact it is somewhat common. It is best to pull the disconnect by the go pedal when not using the MH for extended periods. If it's been sitting for a month this is almost certain to be your problem.

The 2 batteries on the passenger side you are checking are the house batteries. The starting battery is under the driver's floor, you remove the floor mat and there is a steel plate with T-30 Torx screws that covers it (see pic). As Paul D said in his post #4 you can check and charge it without removing the floor pan by using the 2 remote terminals under the hood (see video).

There is also a small AUX battery on certain years, about the size of an exit sign battery, located under one of the seats but it does not do starting duty, it's job is to provide power for things like shifting out of park if the main battery goes dead. It may work the door locks as well. It could be dead too but may charge back up once you get the vehicle running. (This AUX battery was replaced with a capacitor bank on the newest models).

Once you get it running be prepared for some possible error or check engine messages and possible unusual behaviour till the computers all recover.

https://www.youtube.com/watch?v=Z13_A_gwjkw

[CharlesinGA]

Originally Posted by Southboun

Hi folks, thanks for the replies. Both house and chassis batteries are in the passenger side floor and check at 14V. I did reef on the steering wheel as you suggested but nada. Manual indicates a locked wheel or locked engagement system, whatever that is. I'll check under the hood. They ran this about a month ago and did t do anything different. I did notice the steering wheel is cranked to the left which may have locked things up.

Keith

The CHASSIS battery is on the drivers side under the floor. Remove the trim to lift the floor mat just forward of the seat and open the access panel. I see BigB56 posted this, but I'm going to repeat it.

1 Key fob batteries have NOTHING to do with starting, the chip for starting is energized by a magnetic coil surrounding the ignition lock, sorta like a tap credit card you tap on a device in the store. The battery is only needed for the fob's push buttons to send signals to the computers to lock/unlock the doors.

2 CHASSIS battery is under the drivers floor, its a single H8 AGM battery. It MUST be an AGM as the box is not sealed to the passenger compartment.

3 Sprinters have huge amounts of Vampire current draw. One to two weeks of sitting and the battery is dead. There is a battery disconnect on the inside on the firewall near the accelerator pedal. When you park for more than 4 or 5 days, pull the disconnect. Youtube video on how to do it.
Later model Sprinters have the disconnect further inboard and you might have to pull back the plastic trim by your right foot to get to it. This video might help also. Ignore the fact that it is a WBO Revel, its the Sprinter part that counts.

Hope this helps.
Charles

[Southboun]

Good morning folks.

Woke up to a wealth of information from you all and spoke to the ladies. The Good Sam tech did indeed find a dead chassis battery @ 6V. They are going to take the matter up with Camping World, who did less than a poor job orientating them to the unit. They knew nothing of the kill switch. I have recommended this site to them. Thanks to all of you for your input.

Cheers
Keith

[Bnystrom]

Originally Posted by Southboun

They are going to take the matter up with Camping World, who did less than a poor job orientating them to the unit.

There's a shocker!
If this is the worst they have to deal with, they're doing really well.