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NorthOrSouth · 04-22-2022, 08:46 AM

1992 Monaco Crown Royale, 8.3 Cummins, Allison 6 spd.

My transmission seems to give me issues first start up of the year after a winter in the cold. This year I couldn't get it to shift into gear until it was good and warm, probably 15 minutes running before I could back it out.

Then I got it moving and it seems to shift into D and R ok, but now I can't get it to go into Neutral. It'll go back and forth between D and R but the only way I can get neutral is to shut it off and restart it and then it defaults to N.

Pressed the up and down arrows to check for fault codes. In D1 I get 13, 12 and in D2 I get 13, 13. As far as I can tell that seems to be indicating "ECU input voltage low"

I was having trouble last year with a lack of charging. Had the alternator rebuilt and the old regulator was only putting out 11.7 volts so put on a new regulator and it seems to be charging at 14v, which should still be within parameters. But still having shift issue.

Anyone have a clue what's going on?

wolfe10 · 04-22-2022, 08:53 AM

Check voltage with your digital voltmeter at the chassis batteries.

Make sure all connections at the batteries are clean and tight.

If problem persists, check voltage at the two hots (positives) to the Allison ECU and the ground.

If all the readings are 12+ VDC, contact John-- troubleshooting Allison ECU's and shift pads is what he does for a living:
https://www.transmissioninstruments.com/

NorthOrSouth · 04-22-2022, 10:15 AM

Thanks. Voltage at battery 12.6, on dash gauge 14.0 while running, connections all seem to be tight.

Will have to wait til the good ol' outdoors hits above freezing to check voltage at the ECU.

Thanks for the tips and for John's email!

Quote:

Originally Posted by wolfe10

Check voltage with your digital voltmeter at the chassis batteries.

Make sure all connections at the batteries are clean and tight.

If problem persists, check voltage at the two hots (positives) to the Allison ECU and the ground.

If all the readings are 12+ VDC, contact John-- troubleshooting Allison ECU's and shift pads is what he does for a living:
https://www.transmissioninstruments.com/

153stars · 04-23-2022, 09:06 AM

Maybe the old codes due to alternator are just stored and need to be cleared. Several owners have had issues with touch pads. Been shared to sent it out to be serviced cheaper than replacement. The neutral button would have the most use. Has the cover soft cover inlay moved out of position any.
Here's at least one post
https://www.irv2.com/forums/f125/md3060-no-shift-when-cold-329299.html

ihc1470 · 04-24-2022, 09:40 AM

Quote:

Originally Posted by NorthOrSouth

Thanks. Voltage at battery 12.6, on dash gauge 14.0 while running, connections all seem to be tight.

Will have to wait til the good ol' outdoors hits above freezing to check voltage at the ECU.

Thanks for the tips and for John's email!

If the volt gauge is reading correct than it would appear you have a 1.4 volt drop some where in the system, which is a lot. May or not relate to your issue but would be worth checking into.

NorthOrSouth · 04-25-2022, 06:08 AM

That makes a lot of sense, as its not logical to me that D and R would work fine but not N. And now that I think about it, the N feels softer than the other two, like its pushing further down... definitely going to check that out. Thanks for the tip.

Quote:

Originally Posted by 153stars

Maybe the old codes due to alternator are just stored and need to be cleared. Several owners have had issues with touch pads. Been shared to sent it out to be serviced cheaper than replacement. The neutral button would have the most use. Has the cover soft cover inlay moved out of position any.
Here's at least one post
https://www.irv2.com/forums/f125/md3060-no-shift-when-cold-329299.html

153stars · 04-27-2022, 07:35 AM

The post shared is not the only one I have seen about it . Do a search for more info or diy , aftermarket or cheap solution. Or exact test to be sure it's the switch pad. I think I read owners having to warm up the top just a bit with hair dryer when it was pretty cold out.