Could Use Some Help Troubleshooting EMS

[Kjsrbs]

Everything on my 2010 Interstate appears to be working correctly when running the generator except I do not have any display on the Precision Circuits mini-PCS. A/C, microwave, and charger are working. I did not try overloading the generator to see if the EMS would load shed.

With generator off and the RV plugged into a verified 120 outlet, it is as if the RV is not plugged in. The Triplite 750 inverter powers the outlets but the battery is not being charged and the AC will not run and the microwave (light) is off.

I noticed that with the RV plugged in to shore power there is 120 V at the Triplite input when measuring line (black) to ground but if measuring between neutral (white) and line (black) I see about 1 volt. Between white and ground ~120 V. The 120 output side of the charger/inverter is showing the same voltage behavior.

Is there something other than a faulty mini-PCS that could be causing this such as the 120V switchover box? If it is the PCS, does one need to buy both components or can the faulty component be identified by testing? Where is the switchover box in the twin version? How can I verify it is working correctly?

I disconnected battery and AC to the triplite 750 to reset it (Eric of Triplite suggested this) and left it for a while. I guess there must be a capacitor inside as I noticed after disconnecting, switching between remote/invert & DC off & charge the LEDs lit momentarily. After reconnecting, behavior was still as described above.

Randy

[Aircruiser]

I've had this happen as well. I first confirmed that all breakers and fuses were good to go. I was successful in getting the inverter to work again by unplugging the shore line cord, turning off the Tripp Lite, plugging in the shore line, and then turning on the Tripp Lite. I only had the problem a couple of times, but no problems the past couple of years.

[Boxster1971]

RANDY - your problems sounds like the 120VAC transfer switch is stuck in generator mode. The transfer switch is normally mounted near the external power plug. My Interstate has a Parallax model as seen in this link.

http://www.parallaxpower.com/ats301-...-switch-ats301

[Kjsrbs]

Thanks Mike,
The transfer switch was obvious once I lifted the bed platform and even more convenient to get at than I expected. It makes total sense to me that sticking in generator mode explains everything working with the generator running.

I think I will bypass the switch to verify that all works on line power before ordering a new one.

I do think however, that the EMS is also not functioning correctly since the display does not show any lights even when running on the generator. Any threads or advice on troubleshooting that? I will contact their tech support before ordering any parts.

I still do not understand why the neutral side of the 120V lines into and out of the Triplite would be at 120 V when hooked to shore power. I suppose some kind of short in the switch could explain that. Maybe it is not simply the contacts sticking. Perhaps such a short fried the EMS? I am not sure when the EMS stopped working, but it was before finding that the RV would not function on line power.

Any insights are much appreciated.
Randy

[Kjsrbs]

I bypassed the transfer switch so that the coach is connected directly to shore. There is no change in behavior. With all breakers on, I still find both neutral and black wires at Triplite at 120 V relative to ground (~0 relative to each other). So I conclude that the transfer switch is not the problem.

I then tried all breakers off except main and microwave. The microwave momentarily made some slight noise but then no light with door open. The Triplite flashed its lights briefly and then went off. Now (with Triplite breaker still open) I measured ~60 volts (I think) on both neutral and black at the Triplite..... I do not understand why everything works with the generator (except the EMS display) but it sure is starting to look like the EMS is the cause of my problems.

[garry]

What you describe in 1st post is an open neutral.

Should be black (hot) to white or ground 120VAC.

Ground to white never more than 3 VAC under load and normal 0 VAC no load.

Best to use one of the 3 prong ckt testers (leds 2 amber one red).


From what I'm reading there is a problem on your neutral line.

[Alex AVI]

Originally Posted by Kjsrbs

I bypassed the transfer switch so that the coach is connected directly to shore. There is no change in behavior. With all breakers on, I still find both neutral and black wires at Triplite at 120 V relative to ground (~0 relative to each other). So I conclude that the transfer switch is not the problem.

I then tried all breakers off except main and microwave. The microwave momentarily made some slight noise but then no light with door open. The Triplite flashed its lights briefly and then went off. Now (with Triplite breaker still open) I measured ~60 volts (I think) on both neutral and black at the Triplite..... I do not understand why everything works with the generator (except the EMS display) but it sure is starting to look like the EMS is the cause of my problems.

KJSRBS - with everything working with Gen, it is hard for me to think of what would allow it to function properly but yet not on shore power. From what I see in diagrams, the TRN1 Transfer Relay has 3 sets of Line/N/Gnd connections - 1st-Gen input 2nd-Shore/AC input 3rd-Output going to the Power Center. Gen & AC use the same Output going to the Power Center. Logically, if Input1 satisfies a working Output environment, Input2 should be able to also, assuming everything on Input2 is ok. The EMS is utilized by both Input1/2 using same paths from the Output of TRN1 all the way to every load. I would concentrate on the Input side.

Does not hurt, just to confirm - How did you bypass the TRN1? Did you move all 3 Input2 cables straight into Output? Or did you move them into Input1 where Gen used to be? ( which really is not bypassing TRN1, just bypassing Input2 and using a known good path by Gen). I agree with GARRY that it looks like a N connection issue. I would completely bypass the AI shore power wiring and just splice an extension cord straight into the Output of TRN1. OK If you can't find a 30A extension to splice, a 15/20A should be OK just for testing purposes and not running the A/C compressor. WARNING - We only want to establish connectivity but not run a full 30A load. Good luck, wire safely, triple check all connections.

[Kjsrbs]

Garry,
The same behavior at home as at camp so it would be in the cord or RV. Alex suggests bypassing that wiring with another cord to see if it is fixed. I agree that it sounds like an open neutral.

Alex, I disconnected the shore and coach white and blacks and connected them directly with wire nuts. I did no connect the ground wires directly.

Thanks Garry and Alex for the ideas.

Randy

[Alex AVI]

Originally Posted by Kjsrbs

I agree that it sounds like an open neutral.

Randy

RANDY, I missed GARRY's suggestion on the 3 prong tester. It is not an absolute neccessity, but if you have access to one, it is a time saver for testing open G/N or other wiring flubs by just reading the leds Good luck.

[Kjsrbs]

There was an open neutral. The shore line receptacle on the RV was the issue. When Airstream installed the receptacle they did not strip enough insulation off the wires and then pushed them in so far that they tightened the connections onto the insulated part of the wire. It is a wonder that it worked like that for 8 years. I attached a photo. There was some overheating and some melting of plastic but it cleaned up well, so I was comfortable reinstalling the original receptacle. It appears the original used stainless steel connection hardware as there was no rust. It might be hard to find a replacement of this quality.

The EMS is still not working but that appears to be totally unrelated to the open neutral issue.

Thanks for the help everyone!

Randy

[Alex AVI]

Originally Posted by Kjsrbs

It is a wonder that it worked like that for 8 years.

RANDY - That pic, Wow! Amazing it worked that long. You did great job patiently tracking this.

[Boxster1971]

Originally Posted by Kjsrbs

...



The EMS is still not working but that appears to be totally unrelated to the open neutral issue.



Thanks for the help everyone!



Randy

Look for more bad connections in the neutral line. The EMS uses the neutral to measure current flow.

[Kjsrbs]

Since the original post was on my Precision Circuits PCS not functioning, I thought I would update on that issue. I emailed tech support at Precision Circuits Inc. on Saturday of Labor Day weekend. George Cepynsky emailed back on Sunday with the same conclusion about an open neutral and even provided clear instructions on how to find the location of the open neutral.

I downloaded a two page pdf with a PCS operation description and wiring diagram from their website (attached). After emailing George the news that the open neutral was fixed he emailed instructions for troubleshooting the PCS.

“Check for 120V on the PCS I/O Module . Should be 120V from L1 to N and 120V from L2 to N. Next thing to check would be the data cable between the I/O Module and the Monitor Panel. Check continuity on all 6 wires. Then check for 12V and Ground on the white connector on the Central Monitor Panel.” The 5 amp fuse (in the breaker box) powering the PCS was also confirmed as good.

The wires on my 10 position connector did not match the drawing. Looking at the Display Module end of the wiring with the white connector (locking tab on top):
10 9 8 7 6
X gray purple white pink
yellow yellow x pink x
5 4 3 2 1
The white wire is ground and the purple is the 12V power. The yellow wires control the A/C and the pink wires control the W/H. The gray wire is connected to the generator hour meter and tells the PCS that the generator is running by providing 12V when the generator is running.

If the A/C is on, then pin 4 (yellow) provides 12V to the PCS. If the PCS is allowing the A/C to operate, it connects pins 4 and 5. Disconnecting the PCS prevents the compressor from running unless 4 and 5 are jumpered on the connector.

If the electric W/H is on then pin 6 (pink) provides 12V to the PCS. If the PCS is allowing the W/H to operate it connects pins 6 and 2. Disconnecting the PCS prevents the W/H from heating with electric unless 6 and 2 are jumpered on the connector.

George concluded that my wiring is good and that the problem could be either the I/O module (part # 00-10024-000 @ $80.80) or the The Mini-PCS (part # 00-10025-600 @ $221.30).

[Boxster1971]

Thanks for the follow-up. I’ve also had great support from PCI when I had technical questions.