SOS stuck in campground Allison down

I just had my ECU go out on my MH3000 Allison. The repair shop tried to sell me a used one from a school bus for $4500. A total ripoff - just be aware. I purchased a new one from an Allison dealer for $2880. You can buy used ones for about a grand. If this turns out tone your problem this may help
Good luck.

thanks to all of you that have replied. I have exhausted all I can do in a camp ground. Coachnet is sending a tow and Mobile fleet services in wenatchee Wa. will be diagnosing and hopefully fixing the problem soon. I will pass on the info that you guys have shared with me.

I had a similar problem over the Memorial Day weekend. Called Allison. Technician walked me through several diagnostic steps but nothing worked. I ended up getting towed to Clark Power Services, Wentzville, MO. Problem turned out to be a faulty 135 amp circuit breaker. Part cost $27. Total bill was $762. Most of the time was diagnostic time. Hope this helps.

I also have a 1993 coach with the Allison 3060. When I experienced a failure similar to the one you're having, it turned out to be the failure of the electronic control unit, which is what the touch pad connects to. The cost was quite steep, something like $1,000, to replace with a rebuilt unit, but I don't recall the exact price.

Your transmission also has a black box with some 6 or 8 relays, and one or more of those replays could have failed. The box is something line 5 inches square, with Allison written on the cover. The relays were a common type so I just replaced all of mine as a preventive measure. My black box was in the ceiling of my electrical bay.

When I drove charter buses this would happen once in a while. The shop would tell me to turn the battery switch off for a couple of minutes to reset the computer. This usually worked. Good luck.

Open Circuit "G" solenoid. (forward clutch solenoid)

I suspect a 1992 has the two connector ECU and the 24 pin rectangular pass through connector on the transmission case.

I would examine the pass through connector paying close attention to F-1 pin (top row 6th position over) that will have a white wire #104 connected to it. That is the problem circuit.

To determine if its inside the transmission, on the transmission case connector, check resistance between the F-1 (top row 6th position over) and the C-2 (middle row 3rd position) terminal. There should be around 3 ohms. If that checks ok, then you most likely have an an open in the chassis harness. The suspect wire would be, wire #104 (white) that goes between the F-1 pin on the transmission pass through connector and the A-4 pin on the blue ECU connector.

Good Luck,
Doug

Remove all battery power and re-connect. Then try it again.

Unplug shift pad and ECU and reconnect, making sure that all pins are clean straight and tight and that the detents click into place when you reassemble.

I don't have a specific answer to your situation. Can you Google Allison for their tele number and give them a call?

Looks like the list below could help you. Although i dont know what the g solenoid does thats what it appears to be.

Click to view manual