Hymer habitation door step wont open

[Martynovo]

Hymer mercedes 2017 Suddenly habitation door step wont open but it closes ok. Not caught on anything . Checked fuse fine, Stripped door switches and operating ok . Good feed to retract step from dashboard and doorway but it appears there is no live feed to open the step. Have tapped and rocked grey relay under seat which is apparently source of buzzer but makes no difference. S the motor makes no attempt to open the step. All ideas welcome as Im off to France in 4 days and my wife cant get in and out vehicle without step so she is trapped in van until I leap out and manually pull out step. Thanks for any ideas.
Now managed to push in all relays and found buzzer is a separate black box under seat with mercedes stamp on it. Not cured problem. Step is a Project 2000

 

[dalspa]

Assuming that the step is powered off the habitation battery, has this battery got plenty of charge/power? Our step (same as yours) recently would only come out halfway but operated normally when I plugged in the electrical hookup. The hab battery was 8 years old and had served us well. Fitted new battery and step works perfectly now.

 

[Jev88]

If you have 12v confirmed at switches then have you confirmed 12v at the step.motor?

 

[Martynovo]

Assuming that the step is powered off the habitation battery, has this battery got plenty of charge/power? Our step (same as yours) recently would only come out halfway but operated normally when I plugged in the electrical hookup. The hab battery was 8 years old and had served us well. Fitted new battery and step works perfectly now.

On a different thread earlier this week I talked about our batteries - Lithium showing 14 volts. Have tried with engine running but not off EHU as I hardly use it. Will try now! Have tried but made no difference.

 

[Martynovo]

If you have 12v confirmed at switches then have you confirmed 12v at the step.motor?

The step retracts using the motor so power on that but wont go out and it seems no power getting to motor when step down switchws. I took out the switch and tested it separate from all the circuitry in case of corrosion etc but not yet stripped cable to motor to get a contact at entry. Will try that too. thanks

^{_{Subscribers  do not see these advertisements}}

 

[paddymcc]

The step retracts using the motor so power on that but wont go out and it seems no power getting to motor when step down switchws. I took out the switch and tested it separate from all the circuitry in case of corrosion etc but not yet stripped cable to motor to get a contact at entry. Will try that too. thanks

Is it a toggle switch, ie up to close and down to open? If so it simply reverses the polarity to the motor to make it work the opposite way. If so and it works in one direction I think it must be the switch that is faulty.

 

[Jev88]

The step retracts using the motor so power on that but wont go out and it seems no power getting to motor when step down switchws. I took out the switch and tested it separate from all the circuitry in case of corrosion etc but not yet stripped cable to motor to get a contact at entry. Will try that too. thanks

Have you tried 12V from an old battery - flip POS and neg and see if motor moves opposite direction.

 

[Martynovo]

Not much progress so far. Does any one know where the relays are and which ones. It looks like the entire drivers swivel seat has to be removed with the risk to airbag and seat belt wiring. Surely thats not the case. Also on Brownhills web site and generally there are two very different step relay units available but not able to see anything looking like either of those. Am I looking in totally the wrong place? As an A class with no right hand side drivers door access under the seat to even the fuses is very limited.