Check Engine light issue

[lorim]

Let me first start by saying this forum is filled with tons of great advice and people too!

About a month ago I'm fairly certain I completely lost my mind, I bought a 1999 Winnebago Diesel Pusher. I don't personally know anybody who owns a motorhome, I've never owned any RV of any kind, and I've never even rode in one.

Anyway, I drove it home, back to the dealership once, out to OH twice and to a friend to install a break controller. I would say well over 600 miles with out any signs of any issues. Runs and starts like a champ, it has minor issues like a slightly leaky toilet and missing awnings but nothing I can't fix.

When I picked it up from friend mechanic that installed brake controller he pointed out that the check engine light was blinking/on. What the heck, I never had it come on. Then he informed me I was starting it wrong. I wasn't letting the lights cycle before cranking it over. (Well crap) The light was on steady and stayed on the whole way home and is now on steady in the driveway when I let the lights do the cycle thing.

I bought a ScangaugeD to read the code and nothing is coming up and its also not clearing the light either. I finally found instructions and used the check engine button under the dash pod and read the blinks. It's a 5.9L Turbo - Code #278 - Lift Pump Circuit.

I'm torn, at what level of seriousness is this? The light doesn't come on at all when I do a fast start.. I've been driving it all over the place for the past month and honestly didn't have any signs of an issue.
Of course I want to take care of this big rig, I want it to last for many years. I also don't want to be BS'd into fixing phantom issues. What should I be asking and/or listing for when I get somebody to look at this for me? This is my first diesel and the size of this big rig is freaking intimidating.

[Skip426]

Welcome to iRV2.

The, 24 valve Cummins 5.9 l engines in Dodge P/Us , didn't have pressure sensors in the lift pump , instead the Engine Control Module ( ECM ) monitored the lift pump amperage draw , and would set a code if that voltage was out of range. So I would suspect that the electric lift pump needs replacing .
Not sure about access on your MH , but on a Dodge P/U it's about a half hour job.
What I do find peculiar is that on the P/Us the fault didn't turn on the CEL, it was just stored , because the lift pump failing wasn't considered an emissions related fault.

I'll do some searching on the code and re-post .

Many members have replaced the Cummins lift pump with aftermarket ( FASS ?) electric fuel pump and moved it away from engine heat and vibration. You may want to look into that. If I find one of the posts on the subject I'll post a link.

EDIT: BTW, a failing lift pump on these engines is serious as low fuel flow to the injection pump ( VP-44) can cause it's failure , and those aren't cheap .

[Skip426]

Ok, still doing research , but because the code is generated by a time cycle of the pump after key on , your quick starting of the engine might be the key to the light not always being on.
More info in the pdf.
I'm aware that there are four fuses , that supply battery power to the Cummins ECM, and those should be found and checked.
Question ? Is your coach on a Freightliner chassis?
Picture is of a 5.9 lift pump ,diagram shows it's location on the block , and pdf is about the code.

[Skip426]

Here's a link to one of the many FASS fuel pump install threads here in the forums , many others available with the search function.

http://www.irv2.com/forums/f123/fass...ll-342813.html

[lorim]

Yes, its a Freightliner chassis. I've only found one place so far for fuses under the dash pod, I have a bad switch for the dash lights so I've yanked out most of the fuses looking to solve that one. I did find one 30AMP fuse in a slot that says pwr totally melted which I replaced but have no idea what pwr would even be related to.

Thanks for all the info.. this may be much easier for to fix than I anticipated.

[Skip426]

I have the wiring schematic for my F?L chassis , and understand that they are no longer available for our vintage of chassis from F/L.
Problem is that when I have shared the files , other members have said they don't agree with , F/L chassis used by other coach builders.
Could be that coach like mine with a side radiator used a completely different wiring harness than those with a rear radiator.
BUT; I have found that the 4 fuses supplying battery power to the Cummins ECM is a common set up , they may even be inline between the chassis battery and the engine.
I've found fuses in 10 different locations, in my coach 4 chassis and 6 from Newmar. so keep looking , and take notes where you find them there may be a rear chassis fuse box similar to the one with the two white pieces of tape in this picture , with fuses that need to be checked. The is feet of extra wire supplied with the chassis harness so the coach manufacturer can mount them anywhere.

[lorim]

Son came home, we lifted the engine bay to inspect. The engine already has an aftermarket pump installed, whoever did this bypassed the relay and ran the wire the entire length of the motorhome, then up under the dash and directly into the fuse box.. just wow. Not even zip tied or anything, just a direct wire. At any rate when I hit the key you can hear the pump. I'm fairly certain I'm OK just need to do some cleanup on the lazy install.

[Skip426]

Ok, because the ECM isn't seeing the stock pump , your light comes on .
In the link I posted, I think , there was info on installing a resistor ? to fool the ECM.

[Skip426]

Originally Posted by lorim

Yes, its a Freightliner chassis. I've only found one place so far for fuses under the dash pod, I have a bad switch for the dash lights so I've yanked out most of the fuses looking to solve that one. I did find one 30AMP fuse in a slot that says pwr totally melted which I replaced but have no idea what pwr would even be related to.

Melted fuses are not good , could you post a photo of your fuse box ,
I have the owners manual , dated 1997, and the fuse diagram doesn't match my coach , but it may match yours , to help identify the circuit that's in trouble.

[lorim]

The red wire on the plug has been cut down to a nub, sigh. Not sure how easy it will be to wire in a resistor but it has been added to my "to-do" list.

No doubt this rig has some electrical issues here and there, the candelabra lights in the bedroom don't come on, I've changed all the bulbs and tried every switch.. not a top priority but eventually I will figure it out.

Ok, here's the pic (if I attached it correctly) of my fuses under the dash pod. I do know now what every direct wire is plugged in. The yellow wire is the hydraulic system which is on a flip switch, the red wire with the blue shrink is the temp dash light fix also on a flip switch until I can get around to buy/replace the entire headlight switch, something in there has to be bad. Headlights work great but no dash lights. Last red wire with the white is the fuel pump lift that we discovered last night.

On to the faulty fuse, it will be the 25 on the very top, right side directly beside the yellow wire. It should be a 30 but I didn't happen to have one earlier this week when I found the melted one. My owners manual has it labeled as PWR but like yours, mine doesn't match up exactly and there is no label on the box on that one. My guess is that its an ongoing issues, I also found a blown 30 laying in the ashtray when I was digging around looking for something to replace the melted one. The 25 has been in for a week with no issues but the rig also hasn't been out either. We are heading out this afternoon to our local dragway for an overnight trip so I'll keep an eye on it...

[Skip426]

Ok ; well not ok.

The manual I have with a diagram of the shape of fuse box you have doesn't list any fuse for that ; 25 amp location ; and about four other locations .
The diagram doesn't match my fuse boxes or yours , about the only info that might be of any use to you , 25 amp is the largest fuse listed in the diagram I have so the 30 , may have been someone trying to avoid a repair , instead of tracking down the problem.

[dabneytr]

Jleamo1 posted in 2017 about adding a resistor to a FASS pump install to eliminate a check engine light with FASS to fool the ECM.
I installed the FASS in my 98 Fleetwood 36T Cummins Diesel and now get hard/no start when hot after driving 5 miles+. The FASS fuel pressure runs 18-12 psi. I reinstalled old carter pump and no issues 3000 miles hot or cold, and the pressures runs 6-10 psi.

To address issue FASS say install an oil pressure switch to Ground (#2 side) of plug (Hobbs PN 78143). This provides a ground at 4psi oil pressure to the pump and it runs on start. The ECM wire is left disconnected. All works except for a check engine light. I'll have no prime on starts, this may be an issue, but I haven't used the rig enough to know.

The resistor solution in the post uses a 12V relay (use coil side pins 85 & 86). I wanted to clarify if this is installed in the power side (#1 pin side of connector) or do I just connect disconnected ECM to pin 85 or 86.

I can not get the check engine light to go out unless I reconnect the ECM wire and restart.
Another option being considered is to install the ScanguageD and clear codes post start.
Any experience with this issue by the community? Thanks in advance.