[Drea5000]

allison ht741 wont go into drive only low gears
When I select Drive I get the transmission check light. I have gotten the vehicle up to temperature and went and checked the level on the dipstick, which seems to be fine and fluid seems to be new


if you can chime in and let me know what diagnostic protocols you would take I would greatly appreciate it. I’m way in the middle of nowhere in Texas so taking it to a shop that would have the right knowledge is going to be a bit difficult so I’m going to see what we can do while out here or having a general mechanic help out


it’s a 1994. now we will go into one two and three gear and I can drive the third gear up to about 60 miles an hour. I’m wondering if it’s not like a solenoid or something simple how far would I be able to limp the coach let’s see if I needed to get to a mechanic shop that specializes in the Allison  is it advisable to drive in lower gears for a longer time will it hurt the trans? thank you guys in advance

[Jack Houpe]

Did it shift well before? When did this start happening and was there any other problems (air pressure, electrical issues so on) prior to this happening? Lots of Gurus here that have experience with 8/92s they will chime in.

[Johnnyboy]

You are doing good asking questions. I see you have inquired on an Allison chat. I agree you need to fix your alternator and/or charging system. How are your batteries? Both need to be in good shape so the electronic transmission can work correctly. A lot of issues will go away with good voltage.

If you still have check transmission light, I would check your connection at the computer and transmission, disconnect and reconnect the plugs. Check or replace output speed sensor. I know you can pull the 2 digit codes being an ATEC transmission, I have never done it on a Newell, I would look around your computer for a switch and an indicator light or it maybe your check transmission light is the indicator light. I would also look in your Newell coach books to see if they mention anything on how to check codes. maybe someone else can explain the process. I had an MCI with the ATEC and they had a switch and extra indicator light near the computer where you could check the codes.

[[email protected]]

Battery voltage is key for the allison to operate properly. If you are having battery problems that is going to cause issues with the allison computer.

[Drea5000]

Battery voltage is key for the allison to operate properly. If you are having battery problems that is going to cause issues with the allison computer.

Thanks so much. After digging through the Internet, that is what I have come up with and for certain my voltage is not being maintained. I am going to take off my alternator this week. I just called a local rebuild shop to have it rebuilt because it does not go above 12 seven and I’ve measured it at the batteries at the alternator and looking at the voltage meter on the front. It definitely is way lower than it should be, and I believe that may be the problem with the transmission not engaging as I found in the manual that if it’s under, it won’t engage

It did start off at around 12.8 but after idling up and getting the air pressure up, I’m pretty sure it was lower when I tried to engage the transmission

[[email protected]]

Yes typical operating voltage should be in the middle 13s when the system is charging. 13.5-13.8 or so. Does the generator work on your coach? If so for now to test the theory you can use the onboard generator to charge up the batteries. Use the merge switch to combine your battery banks and it should top up the chassis batteries.

[Drea5000]

You are doing good asking questions. I see you have inquired on an Allison chat. I agree you need to fix your alternator and/or charging system. How are your batteries? Both need to be in good shape so the electronic transmission can work correctly. A lot of issues will go away with good voltage.

If you still have check transmission light, I would check your connection at the computer and transmission, disconnect and reconnect the plugs. Check or replace output speed sensor. I know you can pull the 2 digit codes being an ATEC transmission, I have never done it on a Newell, I would look around your computer for a switch and an indicator light or it maybe your check transmission light is the indicator light. I would also look in your Newell coach books to see if they mention anything on how to check codes. maybe someone else can explain the process. I had an MCI with the ATEC and they had a switch and extra indicator light near the computer where you could check the codes.

Well got the charging together and batteries all reading 12/13 volts. Still getting the trans ch if I hit drive :-( any suggestions now? I called Newell and they suggested I completely shut the Coach down for 10 minutes and turn it back on and try to put the key on and see if the code clears. I left it off for half an hour came back same issue. they then told me that I should go to the transmission underneath and unplug it clean it. Make sure that it has some grease on it and plug it back in so I got some jackstands today and I will crib it in the morning I also need to get under there and check the air tanks and drain them so I can do both and I need to grease the shaft so I’ll try that …. hopefully this fixes my issue. I really would hate to go to a shop  if it doesn’t fix it I’m thinking maybe I need to go ahead and try to find ATEC cartridge for my pro link and maybe I can clear it on there I have been searching on eBay, but I cannot find the card

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Did it shift well before? When did this start happening and was there any other problems (air pressure, electrical issues so on) prior to this happening? Lots of Gurus here that have experience with 8/92s they will chime in.

Hey there thanks for your reply so I recently acquired this coach. It had been sitting for 5 to 7 years and I don’t know if the transmission already had this issue. I do know that the batteries were completely drained and on numerous accounts the coach had been jumpstarted for them to move it around without them ever putting decent batteries in it so the code that I get is 23, which has to do with low-voltage and such. the coach was sold to this family that I bought it from with 89,000 miles on it and it currently has around 116,000 miles so they didn’t drive it much and nowhere in any of the documents that I have seen was there any problems with anything

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Yes typical operating voltage should be in the middle 13s when the system is charging. 13.5-13.8 or so. Does the generator work on your coach? If so for now to test the theory you can use the onboard generator to charge up the batteries. Use the merge switch to combine your battery banks and it should top up the chassis batteries.

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Yes typical operating voltage should be in the middle 13s when the system is charging. 13.5-13.8 or so. Does the generator work on your coach? If so for now to test the theory you can use the onboard generator to charge up the batteries. Use the merge switch to combine your battery banks and it should top up the chassis batteries.

My charging looks better but it’s certainly not at 13.7 
Nope gen not working. Cracking but not staying in. Will have Gordon walk me thru troubleshooting when he is free.

[[email protected]]

You are doing good asking questions. I see you have inquired on an Allison chat. I agree you need to fix your alternator and/or charging system. How are your batteries? Both need to be in good shape so the electronic transmission can work correctly. A lot of issues will go away with good voltage.

If you still have check transmission light, I would check your connection at the computer and transmission, disconnect and reconnect the plugs. Check or replace output speed sensor. I know you can pull the 2 digit codes being an ATEC transmission, I have never done it on a Newell, I would look around your computer for a switch and an indicator light or it maybe your check transmission light is the indicator light. I would also look in your Newell coach books to see if they mention anything on how to check codes. maybe someone else can explain the process. I had an MCI with the ATEC and they had a switch and extra indicator light near the computer where you could check the codes.

Well got the charging together and batteries all reading 12/13 volts. Still getting the trans ch if I hit drive :-( any suggestions now? I called Newell and they suggested I completely shut the Coach down for 10 minutes and turn it back on and try to put the key on and see if the code clears. I left it off for half an hour came back same issue. they then told me that I should go to the transmission underneath and unplug it clean it. Make sure that it has some grease on it and plug it back in so I got some jackstands today and I will crib it in the morning I also need to get under there and check the air tanks and drain them so I can do both and I need to grease the shaft so I’ll try that …. hopefully this fixes my issue. I really would hate to go to a shop  if it doesn’t fix it I’m thinking maybe I need to go ahead and try to find ATEC cartridge for my pro link and maybe I can clear it on there I have been searching on eBay, but I cannot find the card

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Did it shift well before? When did this start happening and was there any other problems (air pressure, electrical issues so on) prior to this happening? Lots of Gurus here that have experience with 8/92s they will chime in.

Hey there thanks for your reply so I recently acquired this coach. It had been sitting for 5 to 7 years and I don’t know if the transmission already had this issue. I do know that the batteries were completely drained and on numerous accounts the coach had been jumpstarted for them to move it around without them ever putting decent batteries in it so the code that I get is 23, which has to do with low-voltage and such. the coach was sold to this family that I bought it from with 89,000 miles on it and it currently has around 116,000 miles so they didn’t drive it much and nowhere in any of the documents that I have seen was there any problems with anything

---

Yes typical operating voltage should be in the middle 13s when the system is charging. 13.5-13.8 or so. Does the generator work on your coach? If so for now to test the theory you can use the onboard generator to charge up the batteries. Use the merge switch to combine your battery banks and it should top up the chassis batteries.

---

Yes typical operating voltage should be in the middle 13s when the system is charging. 13.5-13.8 or so. Does the generator work on your coach? If so for now to test the theory you can use the onboard generator to charge up the batteries. Use the merge switch to combine your battery banks and it should top up the chassis batteries.

My charging looks better but it’s certainly not at 13.7 
Nope gen not working. Cracking but not staying in. Will have Gordon walk me thru troubleshooting when he is free.

So I think your voltage should be fine, as long as that voltage is getting to the TCM will be the question. 

So I see you have a transmission check light, which shift pad do you have? Do you have up and down arrow buttons on it? If so you should be able to hold them down while you turn on the ignition and it should blink the transmission light with the codes. Hopefully this works and you can pull the codes. 

BTW, where are you located? Maybe someone nearby has a reader or can come help? This is why its good to put your location in your signature.

A couple of things that may help:
https://transmissioninstruments.com/ecu/
https://transmissioninstruments.com/wtecii/

[Richard]

Those gauges are inaccurate.

What does your voltmeter say about the battery voltage?

Would be very interested in these numbers. Voltage measured at battery terminals with engine off, and measured again with engine running at about 1000 rpm. Those numbers will tell you if the alternator is working properly.

[Drea5000]

Those gauges are inaccurate.

What does your voltmeter say about the battery voltage?

Would be very interested in these numbers. Voltage measured at battery terminals with engine off, and measured again with engine running at about 1000 rpm. Those numbers will tell you if the alternator is working properly.

Hey good morning Richard so I am plugged in. Should I unplug, test the batteries and then start the Coach and test the batteries again let me know if being plugged in is going to change anything. if not, I’ll do it this morning right now