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Ronbstewart · 05-18-2018, 07:48 PM

After starting up and running for 4 to 5 minutes all ac power would drop off in coach (ok on shore power) I jumped the gun and replaced transfer box. Plugged in sure power first everything fine, disconnected shore power started gen and everything good for 5 min and then lost all power (same problem). power will cycle on and off several times and then go off for good. Checked for power coming in to transfer box, power on L6 (red wire) but no power on L4 (black wire) after gen sets for a while it will go thru same phase again when started, so now I'm guessing it may be a generator issue. it has high hours and is what I believe a DC gen that has a built in inverter. RPM varies according to the load, anyone had experience or issue of this type?

NHRA225 · 05-19-2018, 05:37 AM

Post the model #
Flashing any codes ?

Ronbstewart · 05-19-2018, 01:43 PM

7.5 HDKAJ1145H , don't know procedure to check codes, should engine be running or stopped?

NHRA225 · 05-19-2018, 02:56 PM

here ya go !
>> Page 6-

WinnieView · 05-19-2018, 07:53 PM

There will be a flashing light on the Start button which gives a series of blinks to indicate a failure code usually mechanical in nature but only if the genset has stopped running unexpectedly without pushing the Stop button.

It sounds as though your problem is electrical in nature and related to the genset but it may also be elsewhere such as in the lines or breakers post genset but pre-transfer switch.

Here is the Onan HDK Service Guide which includes many troubleshooting flowcharts;

http://www.twinslan.net/~n0nas/manua...0(07-1999).pdf

Corc · 05-19-2018, 08:48 PM

If the generator is running when the power goes out in coach, the control is seeing the proper output voltage. It will not run with bad voltage. You are mot going to get a code if generator keeps running. Good chance you have a simple issue, likely a loose connection or breaker issue.

Check you voltage right at the generator. There is a black access cover for AC connections, top of generator in the front. Check both sides of the terminal block for 120V when power goes out in coach.

Sure sounds like a transfer switch issue, but checking voltage at genset will tell you if it is past the generator issue.

Ronbstewart · 05-21-2018, 06:06 PM

Gen runs ok and running when AC drops off line (runs at idle) I went to junction box on right front gen. Then lug nut bolts are hard to get a good voltage from because of the rust, but seems like low or no voltage on one leg of coach side when power drops off, but all connections are tight and show no sign of arking, going to replace the junction block.

Corc · 05-21-2018, 06:46 PM

Yep thats the block. Should be the same voltage on both sides of block. Bad connections can be tricky. This gen puts out only 120V, just splits in two. You can reverse the load to other 120 line. If you have rust like that, check the breaker on gen too.

Ronbstewart · 05-22-2018, 09:45 AM

First a BIG "Thank you" to all that replied with suggestions and information. Corc you're awesome, I probably would have toyed with it a bit more and then took it to a $90 per hr shop without checking that junction block, some screws were so rusted in the block that I cracked it trying to get it out. Went to Home Depot and got copper connectors with screws, snipped old ends off wires for a good connection. Gen has been running 30 min now with both AC's, TV and battery charger on for load. So far no power loss or fluctuations. If problem is solved I will consider the less than $200 cost of new transfer box and connectors a cheap fix. Thanks to all for your help.