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Truma Six Short Two Long EPS Error


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Call to the field repair specialists in the group. Truma hot water heater when turned on shows two short flashes on the inside switch. Looking at the external LED it shows Six short then two long. Code translates to “Error at exhaust pressure switch (EPS)”

Have looked as far as I can in the flue and no obstruction. No wires are loose as far as I can tell. 

Thoughts? Anyone seen this before and have a hopefully quick fix?

Currently located in central Texas. Hull 1030 LE I 2022

2022 Subaru Ascent "Blue Moose" towing 2022 Oliver Elite I - Hull #1030 "Reset"

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I don’t have a Truma, but the diagrams are pretty self explanatory. 
 

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How far back in the exhaust can you see? Do you have access to a small telescoping inspection mirror or better yet, a boroscope? That would let you see up that elbow as far as the fan wheel. Is there a screen in the exhaust opening? If not you could have a bug nest. Does the fan start to turn or is it dead?

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Can you physically touch the EPS? If so, can you remove the connector or the switch itself ? You could do a resistance check of its terminals. The fan is controlled by FOUR switches, all have to work or the heater won’t light! If even one of the temp switches fails, the fan won’t start to turn (no power available). The EPS senses the correct airflow, then closes. So if it is bad, the fan will start to turn, then stop (power is interrupted). The furnace has a sail switch with a similar function, and you can physically move the vane to test it. I don’t know if the Truma one is built the same way. Knowing the Germans, probably not.

I don’t think you can do much in the field without risking the warranty, and I don’t think Truma sells repair parts yet in this country. The switch is quite expensive.

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Did that help at all, or just muddy the waters?

Good luck.

John Davies

Spokane WA

  • Like 1

"Mouse":  2017 Legacy Elite II NARV (Not An RV) Two Beds, Hull Number 218, See my HOW TO threads: https://olivertraveltrailers.com/topic/john-e-davies-how-to-threads-and-tech-articles-links/

Tow Vehicle: 2013 Land Cruiser 200, 33" LT tires, airbags, Safari snorkel.

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First off, let me say that I do not have any practical experience troubleshooting the Truma AquaGo.  I do have one but I have never had any issues with.  If you looked up the error code, I assume you have the manual.  I wonder what item 4a does?  It is located right next to the EPS, so it may be a method to test the EPS.

Mossey 

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Mike and Krunch   Lutz, FL   LEII #193 “the dog house”

 

 

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4a is part of the water pressure/ temperature relief valve, you lift it up to vent water, and to clean any debris from the seal if it is seeping. This is just like the one in your residential water heater.

Question, do any roving (mobile) RV techs have the ability to troubleshoot these units?

John Davies

Spokane WA

 

  • Like 1

"Mouse":  2017 Legacy Elite II NARV (Not An RV) Two Beds, Hull Number 218, See my HOW TO threads: https://olivertraveltrailers.com/topic/john-e-davies-how-to-threads-and-tech-articles-links/

Tow Vehicle: 2013 Land Cruiser 200, 33" LT tires, airbags, Safari snorkel.

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Found this, is it similar to yours?

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If so that switch is super easy to remove, two wires, two screws.If you don’t want to remove it, get a small piece of electrical wire and “jumper” those grey and white wires. If the heater lights, the switch is faulty. Do NOT leave the jumper wires in there and run the heater more than a few seconds! Short test only.

How far down this warranty rabbit hole are you willing to go, and what is your electrical skill level?

John Davies

Spokane WA

  • Like 1

"Mouse":  2017 Legacy Elite II NARV (Not An RV) Two Beds, Hull Number 218, See my HOW TO threads: https://olivertraveltrailers.com/topic/john-e-davies-how-to-threads-and-tech-articles-links/

Tow Vehicle: 2013 Land Cruiser 200, 33" LT tires, airbags, Safari snorkel.

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First - thanks so much everyone for the responses and detailed ideas / discussion.  Will try to hit all the questions in one spot here.

Electrical skill level. Have not killed myself or anyone else yet 🙂 but definitely not where you guys are. Know which parts of a multimeter to stick where a good portion of the time, and my solder joints hold together but are not works of art. Did learn how to wire a 220 spotlight circuit while it’s hot from an electrician in my college theater days, a skill I try to avoid using.

Took some photos - which I should have done the first time for additional orientation. Attached below.

@John E Davies will try the jumper test right after coffee. Checked and reseated all the wires I can reach on that harness, none appear loose except the orange / blue main blower which seems to wiggle a bit even when fully seated.

 

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2022 Subaru Ascent "Blue Moose" towing 2022 Oliver Elite I - Hull #1030 "Reset"

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29 minutes ago, DunnYet said:

Great picture, see the tube coming down under the pressure switch? That means it is NOT a sail switch. It is a differential pressure switch, with a sensitive diaphragm. It would be possible to carefully functionally test it with a vacuum tester, like a Mity Vac, but that would be risky without detailed specs from a repair manual. It actually looks similar to the $10 one on my home humidifier😳

Make sure the hose is secure at each end and not pinched. If it is open to the air at the far end, it could have a bug in it. Good luck.

John Davies

Spokane WA

  • Like 1

"Mouse":  2017 Legacy Elite II NARV (Not An RV) Two Beds, Hull Number 218, See my HOW TO threads: https://olivertraveltrailers.com/topic/john-e-davies-how-to-threads-and-tech-articles-links/

Tow Vehicle: 2013 Land Cruiser 200, 33" LT tires, airbags, Safari snorkel.

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Update - Pulled the white and grey wires to try the bypass test but my improvised jumper would not get continuity. However, when the white and gray wires were reconnected and system was recycled, the main blower motor activated with a great grinding sound. 
 

I had assumed that the motor was running, just quietly. Looks like the blower motor is possibly bad leading to the unit reporting the pressure sensor low as a overlay problem, not the root cause. 
 

This is looking more and more like a significant warranty situation, so I’m going to button it up, update my Oliver support case, and be thankful we are just out for the weekend and will be back in Dallas on Monday.

Thanks everyone - fortunately we are new enough to our Oliver that we still remember how to deal with heating water for dishes and washing (lol).

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2022 Subaru Ascent "Blue Moose" towing 2022 Oliver Elite I - Hull #1030 "Reset"

AZARCACONMTXsm.jpg

 

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While it probably is a failed motor, it could also be a hardened mud dauber nest in there. Regardless, I don’t think you should attempt a field repair. If it were out of warranty and mine, I would take out the fan assembly for a look-see. Good luck, and please post a followup. If they list the parts on the repair invoice, ask for their prices too. That would be informative. At some point soon these older Trumas are going to be non warranty. If you have not registered it, do so, because it doubles the standard warranty.

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John Davies

Spokane WA

  • Like 3

"Mouse":  2017 Legacy Elite II NARV (Not An RV) Two Beds, Hull Number 218, See my HOW TO threads: https://olivertraveltrailers.com/topic/john-e-davies-how-to-threads-and-tech-articles-links/

Tow Vehicle: 2013 Land Cruiser 200, 33" LT tires, airbags, Safari snorkel.

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