General Boards > Technical Support

Electrical help needed.

(1/4) > >>

Steve Adams:
2001 Contessa Naples:

After being parked for 12 days an electrical power cable shorted against a chassis ground. Visual inspection shows all the insulation melted off the entire cable, about 6 inches long. What I can't figure out is what its connected to.

At this point all coach systems appear to be working. We will start up tomorrow to see if there are other systems that may be impacted. It appears that the cable is connected to a solenoid that is attached to the side of what appears to be a pump. On the bottom of the pump is a large cylinder (filter?) approximately 12 inches long and 6 inches in diameter. There are 4 lines running to from the pump to unknown destinations. I think its the power to the hydraulic leveling system. When the cable burnt up the solenoid chattered quite a bit for about 7-8 minutes before it died down.

What do I need to do power wise to remove the cable and test the solenoid? Getting a new cable should be pretty easy, not sure about the solenoid. Any help would be appreciated.

Thanks, Steve

Edward Buker:
Steve,

I cannot tell you what the system is that had the wire burn up, but your instinct is probably correct. It sounds like this wire could have had the insulation wear through. You described that the insulation melted off. It seems a litte strange that this would take place while just sitting still, so be a little suspicious about that being the root cause. You do need to find the root cause to be comfortable that it will not happen again.

You should be able to take an ohm meter and measure across the coil of the solenoid, with it disconnected, and also measure from a coil lead to ground. You should see some relatively low ohm value, I'm guessing 6 ohms or less, more likely 2 ohms or less if it is a big solenoid, for the coil resistance and a very high value, maybe infinity on the meter measuring the coil lead to chassis ground. You are checking that the coil is continuous, not shorted due to insulation melting, and that the coil itself is not shorted to ground. If that is O.K. , replace the wire and try the motorhome systems until you get that solenoid and pump to function. If it operates normally and that wire is not getting excessively warm then you should be good to go.

Consider also that the wire could have melted due to the 7 or 8 minutes of operation of a system that was not meant to be run continuously, like a starter might do. I think that is not the most likely case but you need to be prepared that if this solenoid/pump started to run again on its own, that you have a game plan to shut it down with switches at the battery or by disconnecting it if that is what really caused the wire to burn. That would then give you time to sort out what is causing this circuit to fire up. Hope this helps.

Later Ed

Steve Adams:
Ed,

Thanks for the detail on how to test the solenoid. My new theory is that the solenoid is the culprit which caused it to draw excessive amperage from the battery and fried the wire. The problem there is that the fuse (mounted upside down on the top of the battery compartment) did not blow.

I started the coach to see if the leveling system would work and it did not. Neither did the superslide. That was a surprise. I'm guessing that the hydraulic pump is doing double duty between the levelers and the slide. The bedroom slide works fine, electric motor, no hydraulics.

Any other ideas?

Thanks again, Steve

Bill Sprague:

--- Quote from: Steve Adams ---....Neither did the superslide. That was a surprise. I'm guessing that the hydraulic pump is doing double duty between the levelers and the slide. The bedroom slide works fine, electric motor, no hydraulics.
--- End quote ---
Our '04 Monteray uses the same pump for the two front slides as for the levelers.  It can be a bad system as there is no mechanical backup for slide retraction and no means to lock the slides in if a hose fails.   If the pump or hose fails with the slides out, you can't go anywhere to get it fixed.  When mine was about a year old, a hose failed just as the slide came fully in.  I nervously drove to Wildwood with the slide creeping out.  It crept out about 4 inches by the time I got there.  


Good luck with the solenoid!

Edward Buker:
Steve,

Had a computer issue this morning and I did not get on the web until just a couple of minutes ago....

 You and Bill are right that the pump system serves both the levelers and the main slide. I am not overly familiar with the solenoid in question but I believe it fires the electric motor, which is a 12V motor much like an automotive small series wound starter motor which drives the pump. The solenoid enables a low current drive circuit to close a large switch, the solenoid in this case, which has contacts that are large enough to handle the current load to drive the motor. There should be a large gauge wire from the batteries to a large lug on the solenoid. There should also be another large lug with a lead to the motor. You can momentarily use a large wire to jumper the solenoid just to see if the motor still operates. If it does then you need to determine if the wire was burned due to an external short from the wire to the frame, or burned because the solenoid was stuck in the closed contact position causing it run beyond its normal duty cycle(internal spring broke or contacts fused together), or the drive circuit fired the solenoid erroneously and continued to fire it. The goal would be to replace the burned wire, test the solenoid, test the pump motor, test the systems that control the solenoid and replace what is the root cause of the problem as well as those components that were damaged by the continuous operation. The Bend Service center may be of help to highlight what the most customary causes of fail are that relate to your situation as well as a good parts source. Hope this helps.

Later Ed

Navigation

[0] Message Index

[#] Next page