HDT chassis vs Coach electrical issues

[Radman-TC]

This was an interesting find last week and maybe relative to GEOs post about grounds...but we will see.

First the set up.
I have a 2001 KW T-2000 N14 Auto shifter built our as a garage coach. A few months ago on long trip to TX I got a yellow check engine light (CEL). It came on after a long-haul up a mild hill when I stopped to use coach facilities. I came back to the drivers seat and the CEL was on. I got back on the road and it cleared in a a few moments. The pattern continued and I called into speak with my mechanic. He didn't seem too worried about it so neither was I.

I had the truck in for service last week and there were "no stored codes" in the ECU. He couldn't make the CEL come on with the truck idling over the next several days. He doesn't like to drive the beast so I headed over to the shop to take a little ride and "bingo" CEL came on with computer plugged in and still no code.

Apparently, the only fault that turns on the CEL but doesn't throw a code into memory are ECU ground issues. Sure enough the fuse that was identified as the ground filter on the ECU was blown. This is a 10amp fuse that has its own water tight holder at the base of the ECU on the N14. This makes no sense to me what so ever - a grounded-fused negative....?

Has anybody ever heard of this... and if so, please enlighten me as to how this works.
We have cleaned and tightened all grounds and load tested batteries but we have no leads left.

What do you think?

Rad

 

[geofkaye]

....grounded fused negative????.....someone was messing with it!....Other than that.....you got me!...Tomorrow I will look at my N-14 and get back to you on the fused ground....It is too late tonight and I'm tired from wiring all day...it's gonna rain and my joints hurt-plus some stiff joints from wrestling 4/6 stranded today.... [new system for generator/shore/trailer/tractor power that I have been thinking about for about a year....huummm I'll get around to it asap!].....today was the day and I have been feeling better and better lately.....geofkaye

 

[geofkaye]

...there is some sort of plug at the ground but I can't get to it yet....I need a new helper-this one is a "wiener"-he needs to go back to college and forget about working for a living.....[kids these days!]....geofkaye

 

[Radman-TC]

Geo,
I think I got this one figgered out.

The fuse is in one of those SAE weathertight connectors located on the back side of the ECU and it is grounding the ECU case. The electronics are isolated and protected with diods and other hi-tech glitter.

While the fuse was blown, it likely happened when we were removing the batteries and or welding on the frame. I didnt know it existed.

Now about that CEL...it seems that the boys at KW saw fit to provide a fan on light in the T2000. A bright yellow light on the dash with all the other idiot lights and the same engine block shape as a CEL. In 2203 they changed the color to green, likely because most of us think yellow is for CAUTION. So it isnt a CEL after all it just tells us the fand is on.

Since I just got the truck on the road in November I had never seen the light come on before. Well it was 40F outside and I get on the highway 2 min from the house so its not that suprising. Now it's loaded up and 80F outside so the fan comes on...duaaaaaaaah.

There is more detailed info on the dual ground loop design and the problems from early N14 configs on the Escapes list.

Anyway all is well with the truck until the next one and I got new batteries too.

Tahnks for looking into the issue and giving it some thought...

 

[geofkaye]

...RADMAN:....thanks for explaining the issue to me.....saves me from taking a crawl tomorrow morning....it was raining today and I just make myself get down in the wet this a. m. something about cold rain that makes me seize up.....I took off the battery post connectors both + and - when I was welding on the bed and frame...."the first time" and nearly had a cow when I discovered that I had left them on the second time!....chit!@!! anyway the Volvo survived that mistake and still operates today unusually well for a truck with 465k on it....thank you for the info........... geofkaye the Rivercity Group.....

 

[Radman-TC]

Geo,
You-da-man for taking the time to even consider climbing under the coach to check it out on my behalf. So thanks for that.

I was at the KW dealership picking up some other parts this afternoon and mentioned the yellow fan light. I asked the 30-year KW / Cummins Veteran Mechanic what was the purpose of this indication. He rolled his eyes and said, “Its just there to confuse us”. Then he laughed and told me of the others that had the same issues for the first 5 years of the T-2000s life before they changed it to a green light. He said they should have just removed it all together.

More humor with the ole T-2000. He did tell me several more stories about issues with this truck and noted that most everything was cleared up before the 2000 model year. “Since then it’s been a pretty good truck,” he said.

Thanks,

Rad

 

[geofkaye]

....went to Louisville today and had a chance to look under the Volvo for the plug on the thinker-box.....can't see it from the bottom side....oil change coming soon and I definitely get to the underside of the brain at that time.....I'll keep you posted....geofkaye

 

[Bob86ZZ4]

Isn't the hookup to the computer located just inside the driver's door under the rear edge of the driver's seat?