Cummins crank but no start

[thewanderer]

I bought my 2011 Ram 6.7 truck last October and it ran fine, except no cruise control. Within two weeks I put a new stereo and Viper alarm in it. In the next two weeks it started intermittently cranking but no start, but would sooner or later start. I took it back to the stereo/alarm people and they said it was the batteries. After $500+ new batteries it started normally. In the next three weeks I started the no start bs again, but would always start sooner or later. Finally it failed to start and I had it towed to the Ram dealer, where they said it was the Viper alarm/remote start causing the problem and disconnected that part of the alarm. A couple of weeks later it started the crank no start bs again. I totally removed the alarm and it worked fine. I took it back to the stereo/alarm people and described the situation with the alarm and the problems with the stereo. They put in another brand of stereo and would get back to me on the alarm situation.
Now it gets weird, with the new stereo I get better fuel mileage with no other changes. Now it almost always starts, but occasionally when I turn the key on, if the dash lights up with the fuel pump icon it will not start even with cycling the key several times. If the preheater icon comes on first, it will start every single time with no waiting. Most times the preheater icon lites up. If I use the engine brake frequently, the Check Engine lite will come on, code loss of communication with ABS module. If I don't use the engine brake, the Check Engine lite will go off and stay off.
Other than those things, the truck runs great, good fuel mileage. Any help or ideas will be appreciated.

 

[MikeT]

Read your post to my wife, she says your truck may be haunted. If it were mine I would go back to the basics, clean/check/tighten every ground and battery connection wherever they go. Even the connections on the batteries. After they are as perfect as they can be made, see what's left, it may be something more sensible or it may even work...Good Luck.

Mike

 

[nlambert182]

I've heard of quite a few instances of folks with aftermarket alarms having similar issues. I have no clue if that's the issue here and I've never had one. Just offering up some ideas.

It does sort of seem like it's losing ground somewhere though since it sometimes will work and sometimes not. Check all your ground points. Almost seems like the alarm installers cut into something they shouldn't have or poorly wired it. There's nothing that I am aware of that would cause your engine brake to affect your CEL. That switch operates an actuator at the turbo.

If the batteries are dying it could be a parasitic drain from either the radio and/or alarm.

 

[thewanderer]

The batteries were near death according to O'reilly, but they never failed to crank. The new batteries are almost capable of working like an EV.
I did totally remove the alarm, but didn't check the connectors, that is my next attempt - grounds and alarm wiring.
thanks.