MCI-9 Transmission won't engage

[Sammy]

Bill, Wire 231 at pin 9 of the shift pad provides ground to the neutral relay - on Allison diagram.
See what you come up with on your bus. 

[Kristinsgrandpa]

Bill, there might not be an external neutral safety switch.

My Allison Transmissions  Electronic Controls Service Manual, dated 1 May, 1990,  on page 2-14, section 2-29-b (2) says
two pressure switches are mounted on the valve body and tell the ECU that the transmission is in foreward, reverse, or neutral. 

The manual shows an explode view of the wiring harness and valve body, but no wire no's.  Foldout 22.

That is probably the neutral switch.

HTH,    Ed.

[NJT5047]

Hi Bill,
You've probably answered this before, but if you have a "do not shift" light, you got a code set.   Probably.  If you cannot read  the codes, hook everything back up and I'll tell you how to arrange to flash out the codes. 
Sammy and Ed both have the Allison HT codes.
What have you done about the transmission cannon plug?  Did you say that the plug was suffering from age or deterioration? 
Are you looking for the neutral start relay?  Likely in front drivers electrical panel.  Appears to ground thru the selector.   Shift pad pin 9 grounds wire #7 vehicle (interface) at the neutral relay?
I wouldn't think the trans has a "neutral" solenoid or such.  I is in neutral when no other specific directional modes are being called for. 
The neutral start could also reside in the RJB.  I'll see if I can pull up my old MUI manuals and see where the units were mounted.  There is a separate, exterior to the trans relay that interlocks with several functions.   Door/air step, hi idle, etc.
All of those circles shown Appendix 1, are bus interfacing connections.  Or they may be on a strip, in a cannon plug, or just attached to where ever it was convenient to do so. 
I may have to go to a meeting of the minds AM tomorrow.  We'll be thru before lunch time...EST.
Feel free to call any time after 1000 hours.  If I don't answer, leave a message and I'll call you right back.  May mean  cannot speak at that moment.  But I'll  be aware that I have a missed call, and you number will be kept for ever. 
My number is 704 650 0235.
Sammy generously sent me some of the same ATEC pages you have 
I just have to have a huge magnifying lens to read it.  But I got one!   
I'm about done for tonight.  Really tart all out.  Had to go ride our new light rail  today.  It's nice.  Way to damn many  folk on that thing going both ways.  Alas.  I got where I wanted to go.  Cheap too.  This was Terri's idea.   Terri's a love, and cute too IMHO, so I gotta do what she wants sometimes.  She does like to go...that's why I rarely pull the toad.  She'll wanna go somewhere!   
Bill, call me any time after 1000..I'm off tomorrow after mid morning and no inconvenience at all.  Be working on an electric car...screw the Arabs....well, lets don't mess with them too much in bus'n season.   But soon i'll be using a lot less of their fuel on  daily basis. 

JR

[Kwajdiver]

Sammy, JR,

I've ordered a used ECM from Nimco, should have it Friday.

I've been looking around the Neutral Relay.

Contact 2 goes to Shift Pad 11.  When the wire is off contact 2, it seems to be getting 14volts from shift pad 11.   Of course my schematic shows 2 going to a 2 pin plug on the transmission.

Contact 1 has 7 volts on it.  Traced it back through stud 15 & 12 on the RJB and to stud 4 in the FJB.  All have 7 volts.
Not sure what this means, it may not matter, being as the bus starts.

What do you guys make of this?   

Thanks for all the input and the phone calls.   

Bill

[NJT5047]

I dunno about the neutral switch, but, don't redo anything until the relay wiring is completely understood.  At this point you may add another gremlin!
It appears per Sammy's prints that the wiring isn't correct.  But, it's been working that way.  Considering the potential year model variations, the bus is probably wired as intended.
If the wiring appears to have been modified...that's bad.  If it is intact, there's probably an explanation for the wiring. 
Does anyone offer a schematic of the shift pad?  That would shed light on a mysterious gizmo.
My initial thoughts would be that as long as the bus starts, don't dink with it.  IF the bus starts in gear, or doesn't start...then you'll have to sort that out.
Did you get the various interchangeability issues on the ECM sorted out?
JR

[Kwajdiver]

Without a schematic, I have no way of knowing if it's correct or not.  Could it be that the ECU grounds the relay.   Believe I will leave it along until I get the ECU tomorrow.  I ordered a transmission connecter, just is case.  Plus a dip stick, remember, mine is broke.  I'm concern that I may have too much oil in the transmission. How much, is too much???

Thanks,  Bill

[NJT5047]

Too much transmission oil is when it blows it out of the dipstick tube and case vent....and anywhere else it can!   Overfilled would not cause your problem.   If it is overfilled, you can drain some out. Which I recommend.   Otherwise, driving it will cause big aireation of the ATF and problems.  Not permanent problems.
Regarding grounding the relay....it could.  You should be able to shift and verify that the lead goes to ground.  My schematic shows pin 9 for the neutral ground.  Shift the unit and see if 9 goes to ground.
As you say, leave the wiring alone until you understand how it's wired up.  Once it's correctly operating, you can sort out all the oddities presenting.
The correct amount of oil is determined by running the engine and shift thru all the gears and then place in neutral.  Check the oil for correct location on  dipstick.  It must be running.  It will be overfull if shut down.  They are designed to be check hot and with oil all thru the transmission.
JR

[Kwajdiver]

 

The ECU came in today,,,, wrong unit.  It has 2 plugs the same as mine, but different type plugs.
Wonder is Nimco will cheerfully take it back and refund my money   

This may mean that I don't get to take the bus to Fred's for painting, and won't get to take it to Arcadia.

Sad in Bill Ville

[Sammy]

Bill, check your e-mail.
Sent you some info on the different ATEC ECU's   

[NJT5047]

Bill, did Nimco understand that you have an HT741 and not an HT748?   Take dig pix of the ECM plugs and fire it off to them. 
Unless something's shorted, or 24V got into the 12V system, it's doubtful that the ECM is faulty.  Having a known good replacement would be nice to rule out the ECM. 
Have you contacted Allison to see if they have any ideas on your problem?  It would be remarkable if they even answered the phone. 
JR

[Kwajdiver]

Is it really possible to talk to Allison.  I have spoke with three Allison Transmission shops. The first one said to bring the ECU in.  I drove to Mobile, Al one morning, 1 hour, they couldn't read it.  Another came from New Orleans, the ECU wasn't giving up any information.  He started tearing into wiring,,,,, sent him home.  He took the ECU, thought they would read it at the shop.  Of course they couldn't.  I went to New Orlean 88 miles, to reclaim it.

Nemco, knew I had a 741.  They didn't have an ECU 1226010.  They thought the 1228283 may work.  I agreed, not knowing that the plugs would be different.

I see the one I need on the internet for $900.00    See another company that claims they can rebuild them.

Would love to have a replacement to try.  Know of one ??  Only need it for 10 minutes.....

Tomorrow I plan to ohm out the tranny connector, see if I can find a problem in that area.

All suggestions are welcome.

Bill

[NJT 5573]

Bill, I experienced a variety of problems with my ATEC.

My shop guy told me to clear the codes and everything would reset and be fine. I cleared the codes and everything reset and was fine.

My ATEC wiring has periods of glitches. Two weeks ago I swung across the highway to back into a yard and got a glitch. Across the road and won't shift!

I cleared the ATEC codes real fast, pushed the R and my full transmission was restored.  I backed off the highway before people in cars could even have known I had a shut down hickup.

I experienced similar problems with my DDEC, but after turning off few extra parameter DDEC settings, I have also made peace with and developed some confidence in my ability to keep one on the road 24/7.

[Kwajdiver]

How do I clear the codes?

Bill

[NJT 5573]

Bill, I have a Eagle

It has a toggle switch on the dash, up to read engine codes, down to read transmission codes.

To clear the ATEC codes, (engine running), I hold the switch down and push R and then D three or four times to cycle the computer and I have a new reset tranny ready to go until the next time.

If you need cheap parts, call, 218.262.4553 ask for Randy, He's got it all.

[Kwajdiver]

My MCI does not have that option.

Ted Keating (TKT) is loaning me an ECU 1226010, like mine, for me to try.  He's overnighting it Monday, I should have it Tuesday.

Wish me luck.  Really getting tired of this problem.

Bill