Engine will not start on new chassis battery but will off Aux Start (coach batt)

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jimivc1

Member
Joined
Oct 9, 2015
Posts
18
Location
Gulf Breeze FL
Leaving on a trip tomorrow and went out this AM to start up the coach to position it closer to the house for provisioning.  I had not started it for approximately 3-4 weeks prior to trying this morning.  When I turned the ignition key on nothing happened.  I even tried using the Aux Start but my coach batteries are old and weak.  I went out and bought (2) new chassis batteries and (2) new coach batteries and hooked everything up.  Went to start coach (300 HP Cummins Diesel) and nothing happened.  Tried the Aux Start and it started right up. 

The Check Engine light came on with a code of ECU 128 Diag 1 Fault 1.  The dash voltage indicator said there was 13.85 V available from the alternator. 

I moved the coach and then went back and checked all of my connections on the chassis battery and measured the voltage (12.56 V). 

Not sure what else to look for.  Any advice would be appreciated.
 
The simplest thing it could be is if you have the kill switch off, next my coach had a solenoid in the compartment adjacent to the battery bay, and one time they stuck and would not allow power through them, a shot of WD40 and a couple of taps and the repair lasted for a couple of years.  It definitely is a wiring problem as it would not have started when you used the emergency start, since all that provides is 2 more batteries in parallel to the coach batteries.

Ed
 
Utclmjmpr said:
Follow the small wire to the switch that controls it.>>>Dan

Couldn't you just use a jumper cable across those two posts? The little wire might be hard to trace but jumping would at least confirm absolutely if that solenoid was the issue. If that is just a disconnect you could even just move both cables over to one post to temporarily bypass it until it could be replaced
 
Utclmjmpr said:
Follow the small wire to the switch that controls it.>>>Dan

Sorry for the delayed response but we just got back from a wonderful 5 days down in Cedar Key, FL (Low Key Hideaway). 

Anyway...traced the wired back to the switch (main battery disconnect).  All was fine but I noticed that the ground was hanging loose.  Re-attached and all worked fine.  Thanks for the help!
 
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