MCI-9 Transmission won't engage

[Kwajdiver]

Sammy,

Received the loaner shift pad today.   Pluged it in, and nothing, same ole problem.

Thanks for the extra paper work you sent me.

Looking over it now.

Bill

[Sammy]

Bill, might need a ProLink now to see what's going on with the ATEC  ECU.
Check out info I sent, might give you some more insight on that setup.
Call me anytime, happy to help as best as I can.
Sammy 

[Kwajdiver]

Sammy,

There's not a prom that I need to change in the shifter pad is there?

Bill

[Sammy]

No, PROM is in the ECU.
Shift pads are not programmable from my experience. 

[NJT5047]

Bill, have you looked to see where the transmission harness interfaces with the coach harness?
Mine has a junction box beneath the drivers seat.  You may be able to trace the trans inputs for fast idle, retarder (this wouldn't cause your problem), park brake power. 
This question is probably redundant, but have you checked for ignition power (12V) at the shift pad?  223B (Red), 225 (Violet), and 235 (White 24V) should be hot when the ign master is on.
210 (Black), and 243(Black), and 230/234 (Black lamp dimmer) should go to ground.
If these are all in order, does the panel lamps work?  Are the grounds patent?
And I've forgotten, but does the 'check trans' light function?  Can you flash out any codes? 
If the ECM  is code free, and the shift pad is correctly powered up, something on the bus such as the fast idle relay may be keeping it from shifting.   The ECMs and shift pads don't cause much trouble.  The wiring may, but the problems are usually at the bus/ATEC junctions.
Don't reckon the PO (or last for hire operator) has the bus wiring diagram?  Something that shows how the ATEC is interfaced with the chassis wiring?  As I said, you may find you can sort the wiring out.  MCI may be able to offer a schematic. 
Good luck!  JR
 

[Kwajdiver]

Sammy, Dallas, JR,,,,,

Thanks for the help as always,  This is what I done this morning.

Sammmy, 

The purple wire, that is patched over something, goes to Pin 4 on the Shifter Pad connector and has 12vdc on it.

Double checked the three fuses, I have voltages on both sides of the fuses.


JR,

On the Shift Pad Connector with power on.

Pins    1,3,5,  have no voltage
Pins    2,4,6,7,8, have 12 vdc
Pin     9, 23vdc
Pins    10, 14 are chassis ground

Dallas,

I've cleaned all the connectors, as discussed.  I have concerns with the data cable to the transmission. 
1.  Do not believe it was locked in place.
2.  The harness side of the connector does not look good. The black plasitc that house the pins, is falling apart.  I cleaned it best I could with the spray and a tooth brush.  Not sure if all pins are making contact.  Perhaps, not all pins need to make contact.  I could use the pin outs if someone has them.  Will try to post a photo of the connector.
Pins    12,13,16 are not used.

Thanks, Bill

[NJT5047]

Bill, if you're sure of your pin-out voltage check, your missing a couple of hot pins.
You said:
Pins    1,3,5,  have no voltage
Pins    2,4,6,7,8, have 12 vdc
Pin     9, 23vdc
Pins    10, 14 are chassis ground

Looks to me as though pin 12 should have 12V, and pin 15 should have 24V?
If the transmission plug is screwed, that's a problem.
Hope a standard HT748 plug is the same.   
Reckon I'd mount a couple 12 post terminal blocks in the engine room and remove the old plug and use the terminal strips to connect the two harnesses together.  Even if that isn't your problem, the trans plug should be repaired.  It will be a problem.
Get someone to cut a trans plug from an ATEC coach...maybe Luke, Nimco, or Sam Caylor has an MC9 with the trans harness intact.  They won't remove it, but they'll cut the trans end off and sell it.  If the plug was your problem, the ATEC would set all sorts of failure codes. 
Does your Check Trans light work?  Grounding "J2" pin "D" will activate whatever memory the ATEC ECM has stored.  You may have a momentary switch in the bay with the ATEC ECM for this purpose.   Or, use a Prolink if you can find one with HT748 data.
The bus engine oil pressure appears to be linked to the transmission.  I'd assume that it wouldn't shift without seeing engine oil pressure.  Nothing has been dinked with regarding the oil pressure senders? 
You have tried all the gear positions...and not just D or Reverse? 
Does your coach have a Robertshaw low oil pressure/hot water/low water shutdown unit? That thing could interlock the transmission. 
JR 
 

[Kwajdiver]

Guys,

Had the Allison man here today.

Pin 12 does not apply, this is a 24v system

Pin 15 is a problem, O volts   Does 15 get 24 volts from the ECU.  If so, this could be a problem.

The ProLink, was unable to read the ECU... hummmmm.....

I believe I may be in luck on the Transmission connector.  The schmatic that Sammy sent me, has five pins not used.  I have five empty sockets.


JR,

The Check Transmission light does not lite.  I need to check the bulb.
Oil Pressure is fine, as I seen on my gauges
I tried all the buttons, nothing will shift.
Not sure what a Robertshaw  system is, where do I look?

The Allison man, took the ECU, with him back to New Orleans.  He spoke with someone on the phone, (he's boss I think).  They have a tranny in the shop they believe they can test it on.

Still no clue on the Fast Idle, not working.  Really haven't even looked at that.

Thanks for all the help!

Not going any where in Gulfport, Ms.

Bill

[Sammy]

Pin 15 gets power (24 volts) from the interface. Remember : ECU is a 12 volt unit.
Need MCI diagram, to see where Allison harness "interfaces" with the coach. 

[Kwajdiver]

Sammy,

Thanks for the reminder, you are correct.

Where is the Oil Pressure Switch located?

Where is the Accessory Power Fuse?  Looks like an 8 amp fuse, possible on the same block as a 5 amp.  24vdc runs throught the Accessory Power Fuse, then to the 235 wire.

JR,

Looking on the schmatic,,, I see the 235 and 225 tie together. I don't have the 225, but where is that interface.  It's not under the driver, as I believe your bus mayt be.

Thanks,

Bill

[NJT5047]

Beats the $#*+ outa me!   Look for any wiring that's encased in split loom.  Most ATEC harnesses are inside black split loom.  The cab harness (if OEM install) comes out beneath the center ramp area. 
Is your shift pad mounted to the RH of the driver?...or LH?  The cab harness exits, more or less, below the shift pad. 
Mine has a "T" off the cab harness that runs across the area above the brake treadle valve.   It interfaces with the kneeler, high idle, and park brake. 
It won't shift when kneeling.  If you shift with high idle, it knocks off the high idle.  But it does shift.   It will also shift with the park brake set...won't go, but it goes into gear.
Look up inside the spare tire area and see if you can locate the cab harness.  If so, see if any wiring exits the harness and routes over to the bus electrical panel. 
My guess is that the interface is in the front electrical panel...next guess would be at the rear junction box.    MCI may have made a harness that runs down to the ATEC too...
Do you see any groups of wiring that separate off near the converter?  TTBOMK, any wiring near the ATEC ECM and converter are solely there for those items.  There's not other wiring in that area.   This is going to take some detective work, because finding a manual with accurate information is not likely.
The bus OEM wiring looks different than than the ATEC wiring.  ATEC has actual colors with numbers imprinted on them.  MCI wiring is generally black, but has numbers stamped on them.   The numbers allow going from end to end and locating the wires.   
White MCI wiring is usually ground (not always), and black is supply. 
What have you decided to do about the trans plug? 
Is your ATEC a retrofit or is it OEM?  Does the cab harness run down thru the tunnel? OR is it routed outside the tunnel below the floor.   There are no splice connections inside the tunnel.  So it you can locate both ends of the harness, you'll be able to follow the additional wiring to power supply...etc.
There's also a small tunnel that runs over the driver's side front axle. The tunnel comes out under the drivers seat.  If retro, your cab harness could be routed thru that area.  Look for the ends of the harness and follow any leads that run into the coach. 
That's the only ideas I have...at this time.
Pin 15 is pulled off the ignition master.  Should have 24V whenever the ign is on.  I believe that's a light?
Good luck!  JR
BTW, have you considered trading your ATEC for an HT740?  Be some work to change out, but damn sure would make troubleshooting simpler in the future.   It would work fine with your MUI engine.   The hardest part would be installing the shift cable...an air shifter would solve that problem.   An ATEC HT748 is a valuable transmission.  Worth more than an HT740.

[Kwajdiver]

Guys,

A have a page of a Wiring Diagram  it is Appendix I Copyright 1991  GMC.  FigureI-1  jSchematic View of the ATEC transmission Control.

Top left of the page is the Selector, this is the connector to the shift pad.   Pin 15 is 24v ign.  The question is,,,  Where is the Vehicle Interface Connector.  Then were does that 24volts go from the 17?

Thanks Bill

[Kwajdiver]

Disregard, the last post.  I found it...

Bill

[Kwajdiver]

JR,

I do not use the Pin 15 voltage. That is a blank.   I've followed your thoughts on the wiring, of course you are correct.

My harness runs in the tunnel.  I'm thinking now it very well be the ECU.  I see to have all my voltages.

If you don't mind, I would like to give you a call.  Need the number.

Thanks,  Bill

[Kwajdiver]

Guys,

Here's an update.

The prints I and Sammy have are sort of a guide.  None have been right on.  That has caused me lots of heataches.
I've been looking around the Neutral Relay, thought I might find the problem with the Fast Idle.  Some how, it seem to be connected to the tranny problem.

By removing the wire of the Neutral Relay, screw 2, (located in the Rear Junction Box) and jumping a wire between ground and screw 2, I was able to restore my Fast Idle....

Then I jump ground to the wire I removed from screw 2...... Wow !  With Sammy loaner Shift Pad, it lit up.... with the Do Not Shift light flashing.....  However, the tranny would not engage with any button.

I changed out Sammy's shift pad for mine....   No "Do Not Shift" light, but then again,,, I've never seen it at anytime. Funny, didn't know I was suppost to have one until I started this mess.....

WOW !   I have first gear, nothing else, but first did engage.  It boils down to a problem around the Neutral Relay area. The print shows a Neutral Switch at the transmission, but so far,  unable to find it, or a wire going to it.

The wire off the relay screw 2 seems to go to the shift pad for the Do Not Shift light.

Input welcome!

Bill