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Old 07-20-2016
Alfa Alfa is offline
Senior Member
Join Date: May 2015
Location: Austin
Posts: 753
Default DDEC 1 Check Engine Light Confusion

The last time to put my coach in storage, I noticed that the check engine light was very faintly blinking when idling. All of the gauges looked normal, so I shut her down and checked all of the fluid levels.

Everything looked normal, oil, transmission, and a nice green site glass. So I decided to tap on the side of the coolant tank and it sure sounded hollow, so I decided to get some Fleet charge and add about a half gallon of 50/50 mix. I ran the engine for a few minutes and no check engine light but the tank still sounded hollow, so I added about a gallon more mix (with about a pint pouring on my head and shoulders when I wasn't paying attention to the funnel...)

Now when I start the engine, I get a solid check engine light. I also noticed that the lower half of the sight glass is no longer green, but more the color of the Fleet charge. So I am thinking that I need to add more coolant, but I thought that I would press the engine test button and decode the blinky lights to see what my DDEC 1 was complaining about.

So, I stared at the blinky lights and they didn't make much sense to me. The manual says that there will be about a 3 second pause between codes, which will be one or more flashed for the first digit, then a 1/2 second pause, then one or more flashes for the second part of the code. Mine seems to be a little different.

Can anybody help me understand what my DDEC 1 is trying to tell me? In the video, the engine is running at normal idle. Near the end of the video, I show the temp and oil pressure gauges and switch to high idle to show the oil pressure moving.


Diego Alfarache
Austin, Texas
1988 WB40
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