shift does not display and motorhome does not start

[CarlCaddy]

the 1992 Newmar Londonaire motor home transmission push button has no display on the shift and the engine will not start.  The chassis is a Spartan.  This is an Allison 3060 WTec II.  Last summer  I replaced the VIM with a used one from RV Chassis parts.  It worked and we took one trip last summer.  The second start on the road was difficult.    Fortunately it did start and we determined (best guess) that the probable cause was a bad ignition switch which was replaced. 
We went to use it this past winter and again no display on the shifter and the engine does not start.

Checking out the voltages on the VIM
L1-K1 = 0 volts
R1-K1 = 12 V
J1-K1 = 12 V
F1-K1 = 0 V
C1-K1 = 12V
J1-F1 = 12V

F1-K1 should have 12 volts per the diagram and is connected to the neutral start relay.  This may mean that the neutral start relay is the fault.  I have no idea where this is located or if this is the cause.  Jumping F1-J1 on the VIM with the ignition switch on, the engine starts and runs although there shift panel has no display.

Any suggestions would be appreciated. 

Carl

 

[Gary RV_Wizard]

There is an interlock that prevents engine start unless the tranny is in neutral. If the shifter has no power, it can't signal "neutral".  So, you need to figure out why the shifter isn't powered. It almost surely gets its power from a relay associated with the transmission controller module. A loose connection or bad relay is likely the cause.

I had a similar problem with the Allison 3000 in my '04, an intermittent wire connection on one of the relays in the back by the TCU.  If the engine was already running when it opened, the shifter display turned off and the tranny dropped to 4th gear. If not already running, it could not be started.  Two of us went over every wire and relay and even swapped relay modules, to no avail.  The next day a 3rd guy did the same process and found the bad connection within 5 minutes.  It was a matter of wiggling the right wire in the right manner. By the way, it was a connection at the relay end of the wire harness. The relay snapped into a base and the wires connected to the base, so swapping the relay did not change the wiring problem.  We re-crimped the wire and all was well again.

 

[Robert K]

When I kept getting a do not shift light on my Allison 3060 it was a corroded butt connector. It was in the looms of wires under the cockpit.Good luck
Bob