Do Not Shift

[jplante4]

Just and informational post about this problem so it shows up in future searches.

I was moving the Sahara to the airport where I work part time so I could dewinterize and get her cleaned up for the season. I had just had a 6 pole plug installed for the toad along with a charging line to the toad battery. It looks like 14 ga. wire, which I think is undersized, but that's a topic for another post. The charge line goes from the coach chassis battery directly to the battery on the Equinox and I'm getting 13.3 volts at the toad.

Anyway about a half hour into drive, the shift pad blinks, the DO NOT SHIFT light comes on and the tranny (Allison 3000) downshifts. Things go back to normal, I upshift into 6th and a few minutes later it happens again. Back into 6th, but the third time's the charm, the shift panel goes dark, the tranny goes down to overdrive lockout. Also, the speedo goes to zero.

I'm about 10 minutes from the airport and a half hour from the shop, so I pull over and think things out. I can't shift at all, no neutral or reverse, and I'm in some higher gear. I decided to turn around and limp back to the shop. Getting going in a higher gear really brings the tranny temp up, but it leveled off below red line so I'm happy. I tried to get codes from the shift pad, but it's completely dead. Meanwhile, I'm a half hour late for work at the airport.

I did some research overnight (Thanks Brett Wolfe for your insight on this) and decide that it must be a wiring issue. I started at the 2 ECM fuses in the front of the coach where the fuses are good and I'm getting chassis voltage. Next to the ECU under the shift pad and sure enough one of the plugs is loose. I plugged it back in and turn on the ignition and now I'm getting codes blinks from the dash. Progress, but still no start and no power to the ECU.

I teach my flying students many things I learned over the years, and one of them is if you do something in a plane and something bad happens right after, undo the last thing you did.

I looked at the area around the chassis batteries where the tech hooked up the toad charge wire and there it was; the power to the ECM just sitting there, sometimes making contact but now not.

Usually 2 simultaneous electrical issues will run up the repair bill in a hurry. The online research I did pointed out several areas to check and help me to avoid a big bill.

Also kudos to Allison for just going into safe mode and not stranding me on the road. The tranny protected itself but didn't quit completely.

[toedtoes]

Glad it got resolved. I would change out that 14 gauge wire for 4 gauge.