Community Forums

rpaldrich · 09-20-2021, 04:29 AM

Hello,

Under high throttle / low RPM, high throttle / high RPM, high load conditions, I am getting a CEL that mostly flickers, but sometimes is steady. When I was starting from a stop light, it flickered multiple times on our most recent trip, and on same trip, when I was in the mountains climbing a grade, it was steady and nearly didn't make it up the mountain. Crested at 25mph decreasing.... I'm not interested in driving the coach except to test out solutions, and have neither time / money to drop it at garage.

During the past year, the engine was replaced along with the VP44 as well as the lift pump (purchased it with known bad engine).

1) The coach is factory standard except for the lift pump (FASS). What diagnostic / preventative / proactive things would you install / look at that may solve the CEL but also prevent future problems (if it doesn't fix CEL).

2) I intend to change all three fuel filters (the water sep near radiator, the fuel filter mounted to engine, and the frame rail filter).

3) I have checked coolant level in surge tank and it is good.

4) No idea what other "sensors" trigger the CEL. Anyone have a list of trigger conditions?

5)I cannot get the code to "hard set" on, so I cannot read it with my diagnostic tool ($100 HD truck reader from amazon). I have heard that VMS will log it if it happens while VMS connected. Anyone know positively that Bluefire will do the same?

Thanks!

Skip426 · 09-20-2021, 10:03 AM

With the conditions you describe , TPS ( Throttle Position Sensor ) is possible but should set code .

Check connections from TPS on the pedal to the dash .

Every code list should have an indication of the sensor involved with setting the CEL/code.
Coolant level should be at the MAX cold line , anywhere below could trigger the low coolant warning, when sloshing around .

Is your coach on a Freightliner chassis ? If so do you know the chassis build date ?
Freightliner chassis underwent a MAJOR wiring harness change Jan 4 1999, but many coaches of the 1999 model year were built on 1998 chassis .

EDIT: Info at this site might help .

http://www.diesel-service-parts.com/...ult-codes.html

rpaldrich · 09-21-2021, 06:43 PM

Thank you -- that website will be useful if I can get the code to stay. On my coach / engine combo the code does not get "hard" set unless engine is turned off with the CEL on. Of course I can bring it in to Cummins, but I would prefer to solve the problem myself if able.

Appreciate the link

rpaldrich · 09-21-2021, 06:54 PM

Quote:

Originally Posted by Skip426

Is your coach on a Freightliner chassis ? If so do you know the chassis build date ?
Freightliner chassis underwent a MAJOR wiring harness change Jan 4 1999, but many coaches of the 1999 model year were built on 1998 chassis .

Yes it is a Freightliner XC chassis built on Feb 2nd, 1999.

rpaldrich · 03-23-2022, 05:26 PM

Solved (I think).... after that loss of power and associated CEL, I started to think maybe it was fuel starvation and sure enough it was a very kinked fuel hose to the engine mounted fuel filter. Replaced the fuel hose and problem solved. I hope it does not affect VP44 longevity, but driving it now it has a lot more power and no CEL.

I have VMSpc hooked up and ready to record any future intermittent codes, but so far nothing.

Next trip is a 1600mile journey so we shall see.

jacwjames · 03-26-2022, 08:39 AM

Sounds like you've done all you can to be proactive in maintaining your rig.
One suggestion might be to add a fuel pressure gauge. I did this when I installed my FASS system and can see the fuel pressure my CAPS pump is getting prior to startup and while running.

rpaldrich · 03-27-2022, 04:14 AM

Quote:

Originally Posted by jacwjames

Sounds like you've done all you can to be proactive in maintaining your rig.
One suggestion might be to add a fuel pressure gauge. I did this when I installed my FASS system and can see the fuel pressure my CAPS pump is getting prior to startup and while running.

Jim -- yes I am absolutely looking at installing one. I have heard of some very different installs though. Mainly how to tap into the line (my plan is post engine mounted fuel filter but prior to VP44), what type of sensor to use (analog vs digital), and how to get that data up to the dashboard.

I'm going to install myself. Do you have a recommendation that will be easiest?

jacwjames · 03-27-2022, 07:42 PM

My secondary filter had a tapped port to install a sensor. Other IRV2 member had used the one that I went with.

https://www.ebay.com/itm/27441097649...53.m2749.l2649

Had to have an adapter and I went ahead and bought a 40' extension cable, although you could use a twisted pair.

https://www.ebay.com/itm/29123042281...53.m2749.l2649

https://www.ebay.com/itm/29443123077...kAAOSwDGxhVu1Y

I had enough room to install the gauge in my dash, easily visible when I turn the key on and while driving. At startup my gauge reads ~16psi, on hard pulls it may drop to 13psi.

vettenuts · 03-28-2022, 06:19 AM

Not sure if Cummins is the same as OBD II in a gas vehicle, but in a gas vehicle the blinking light indicates a misfire.

rpaldrich · 03-29-2022, 04:28 AM

Thanks - it was not a repetitive blinking like a misfire or limp-home mode in a car. It was an intermittent light that was coming on due to some sensor "seeing" a problem.

I'll have a trip report after our next big one

nehog · 03-30-2022, 02:06 PM

I'd certainly scan for codes. Get a Scanguage-D (I'm selling one in the marketplace) and that will give you the code information. Then log on to Cummins' site and get the code's meaning/diagnostic information.

Fefanatic · 03-31-2022, 07:48 AM

If the check engine light came on it set a code in memory. Your scanner may not show it but it is there. I learned that lesson the hard way in my quest to resolve a ecm issue I had a couple of months ago. I had to get a insite scanner to get all the codes and was able to diagnose my issues after that. Had I not done that I would have replaced a caps pump that wasn't the issue.

Make sure whatever scanner you use gets all the codes.

I was using Bluefire for motorhomes and it failed to give me all the codes I needed to solve my issues. You get what you pay for.