Hello...this is the first time I've ever posted here on the forum. Usually I just read posts and learn from other experts...unlike myself . However, I have a question that I hope you may be able to shed some light on or at least point me into the right direction. I have a 92 MCI-102c3 with a Cat C-10 and an Allison 740. My question is this...Last weekend I drove about 800 miles without any issues coach worked flawlessly. This last Thursday I decided to get some fuel so as to top the tank off. When I started the bus, the "check trans light" did not go off but the transmission still went in to gear and ran perfectly. I checked the fluids and all was fine but the light stayed on. Today when I fired it up (since I'm bringing it into the shop this evening)...It went into reverse but will not return to Neutral unless I shut it off then it defaults back to Neutral. have any of you ever heard of the bus not being able to return to neutral from any of the drive positions? I'm bringing in the bus tomorrow but I was trying to learn as much as I possibly could prior to this
thank you in advance
Ray
this is a pad/button shift ... ??
1st you probably don't have a 740 it's probably a 748, but some how it is in the diagnostic mode be sure wire 222 has a good ground and check wire 215 it needs a good ground also if wire # 216A is grounded it goes into the diagnostic mode.Do this 1st stop the engine and turn the test switch on and restart the engine
Do you have a Prolink to check for the hard codes ? the 700 series ATEC can be a nightmare to chase down the problems
good luck
Thank you very much. I will do the suggested procedure. Wow what a great resource you guys are. Oh it is a push button shifter.
Sorry for the apparent carelessness...but where is the test switch you are referring to?
Thank you for taking the time to respond
Ray
Quote from: rgrimard on December 06, 2015, 09:30:36 AM
Sorry for the apparent carelessness...but where is the test switch you are referring to?
Thank you for taking the time to respond
Ray
i am super old school...linkage/cable only. BUT I think the test Sw is either a sequence of buttons on the pad or a stand alone sw on the shift pad...
mode maybe.
I have the same tranny in my 102C3. The ATEC system is kind of quirky. Definitely
A 748
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How do I get this shifter to clear or give me the fault? The selector does not have a mode button just r,n,d,1,2,3. There is a red display but how do I activate it with this shifter?
Free bump. Anyone helping you out yet?
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Scott, where is your test switch located on the MCI C most are in the pad or shiftier area,do you have a pad or shift tower? I gave my owners manual to a person and what he needs is OM1957EN manual to tell him how to retrieve the codes from a tower.I never done it with a tower I used the Pro/Link, the 700 series just has soft and hard codes the hard codes takes a Pro/Link I know that for sure
Well, my C3 bus is in Michigan and I haven't been home in a year. Will be there in a few weeks tho. I think my test button is elsewhere cause I haven't seen it on the shift pad. I do indeed have the pad not the tower.
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Not sure if the tranny diagnostic is in the same place but my manual say the engine diagnostic switch is located LH rear baggage compartment behind panel on tunnel and in a hinged box right of the drivers seat at the junction of the floor and drivers modesty panel. My manual basically says , yup , you got a tranny .
My other book says by the ac switch by the dash. I have an 86 and it doesn't have that.
So the first book says hold the switch on and count the blinks short pause is the next digit 2 digit per code I have the chart
rgrimard
I have almost the same setup as you. The switch Clifford is referring to is in the third bay, inside a hinged cover.
However, you can retrieve the codes by simply turning the ignition to the first position, then press the diagnostic button on the left hand panel. It's a rocker switch, press it one way and it will start blinking the check engine codes, press it the opposite and it it should blink the trans codes. If your check trans light is burnt out, you can still listen for the relay clicks. If there are codes stored, the TCU will blink/click the codes one after the other. It can be confusing though as some of the codes are double digit. If you don't here the clicking or see the light blinking, you will have to use the toggle switches in the third bay under the cover on the drivers side. Be super careful not to disturb the wire harness too much. You can really make a mess for yourself if you knock a wire loose. I try to only move wires on either the ECU or TCU when I need to.
Last but not least, if your shift pad is working correctly, you can clear the TCU codes by again turning the key to the first position, and shift repeatedly from D to N till you hear a high pitch sound.
I currently have a bad forward pressure switch I need to work on, so I know that when the trans stops going into gear I need to clear the codes in order to get the trans to go into gear. So far if works every time... I hope to get the time to track down the problem before it worsens.
I don't know where you are, but be super careful who you let work on your trans, there are not a lot of shops that are competent with the ATEC trans and often cause more harm than good.
Pull the codes and post what they are and I may be able to help further, or perhaps a REAL expert may chime in.
Jeff,
definitely not trying to be a nitpick...so take this with half of a quarter of a grain of salt, but i think the abbreviation is indeed "ATEC" not ATEK. Your sig also spells it ATEK which if someone were to google, or try to search in a manual, wouldn't come up with the results they were looking for. Allison Transmission Electronic Control I think is what it stands for. Anyway, I agree completely that if you let someone tinker with your ATEC trans, you're asking for trouble. When I get home I will spend some time trying to find said switches. I don't have key ignition but rather just an ignition switch so I'll experiment...
Kontrol or control ;D but is ATEC,I think he just has a ground he needs to chase down
the manual I have has the codes and diagrams, I'm just hanging out, if he gives us a number, we can go from there. It also gives the power and ground numbers. It's a newer version so I think it's got the correct info.
I found how to retrieve the codes for him
Start the engine
Shift the gears and then place in neutral
Hold the test switch on with the engine at idle
The important Codes will flash
Now all he needs to do is find the test switch ;D
To Clear the codes
Stop engine
Turn the test switch on
Start the engine
Shift from neutral to reverse back to neutral and stop the engine the codes should be deleted
Wow guys this is an awesome ..... great...effort by all of of you. I like the above gentleman do not have a key...just a master on button and an engine start. as soon as we figure out where the test switch is I'll be able to clearcomputer. The transmission goes smoothly through all the gears now that the fluid and filter has been changed and drives nicely. However the light is still on. Disconnected that battery completely 12 and 24....left it off for a few minutes but the check trans light remains illuminated. Where is this switch seems to be the mystery. Perhaps I'll call Mci and see if they would be so kind as to tell me. Thanks again guys . I'll let you know if I find anything. In the mean time keep the ideas coming.
Regards
Ray
Scott, Thanks for the correction, I have made the adjustments.
As for the code clearing procedure, I read the same thing Luverbus has specified, however on my transmission control the procedure I specified in my first post is the one that works in my case. There must be several different procedures. Dang Engineers.
rgrimard
I don't know how long you would need to disconnect power from the TCU, to "clear codes" but there is a fuse, again on MY bus in the battery bay that you should be able to pull to disconnect power from the TCU to attempt to clear codes. I would think overnight would work.
I don't think you will achieve much using that to clear codes. Again with mine, the codes come back within 20 min; best to find the correct procedure for your bus configuration.
Let us know how this turns out, I'm always interested in hearing how these transmission issues get resolved.
Good Luck!
Just pulled the fuses...my by also had fuses in the battery box. I'll check it tomorrow and let you guys know what I found.
Ray
So we gave you three places to look, per manual, did you look there, oil and filter is seldom the problem.
He needs to be sure what transmission he has in the bus and tell us
Ok guys this is what I've found. First of all I HAVE located the ATEC module and test switch;it was in the rear luggage compartment (driver's) side on the tunnel ...4 zeus fasteners and it swung down. Thank you very much for sending me in this direction (I would never have located it without your help).. OK so I followed all of the procedural steps you all sent me but unfortunately to no avail. I also found the port where one must plug in a Pro/Link to the right of the drivers chair on the ground...also with the expert directions you all provided.
The test switch (at least on my bus) is a momentary switch located under a switch safety latch which I toggled and nothing seemed to change with the "check Trans" light after I powered it up and down (following the gear cycling steps you sent me) I even tried to hear (or see) if the check trans relay energized when I hit the switch...nothing. The check trans light still glows brightly (defiantly).So...I followed the directions from iluvrbus and located wires 222,215 and 216A. Wire 222 has great continuity to ground (as expected) however wire 215 (was supposed to be grounded and according to the schematic goes to the check trans relay) came up as an open...no connection to ground. If this is a great possibility...then what should I do? Should I splice in a ground connection? Trace it back..uggh? wire 216A also came up as open (not grounded). Only suspected reading was wire 215.
FWIW the bus fires up without any beeps or blinks and goes in and out of the selected gears back and forth to neutral with out any issues. What do you guys think?
Ray
So my book says 202, 223a +12volt. 203 continuous 12v powered memory, 208, 209 battery ground, 201 chassis ground ,210a ground. 215 is scanner read wire not ground. You must hold the switch to Trans until it finishes flashing the codes. Turn on main switch and hold check switch to Trans and count the blinks. Check battery cables. Make sure they are tight.
Is the "check trans" the only light staying on ? if so it's probably a bad check trans relay or a bad engine oil switch wire 215 is a mandatory interlock to the oil pressure switch on the engine
Hmmmm, and the thot plickens.
Are you referring to the "check Trans" light on the dash? Truth is, on my C3, that silly light goes on and off at will due to a little short somewhere in my left armrest panel (the one with the dash light dimmers). I can move that panel around or bang on it and the "check Trans" light will shut off. Me thinks that if the Trans is really malfunctioning it will not let you go into gear and I think it even beeps at you from what I remember when mine was giving me fits. So if it's shifting fine, your fluid level is good and the fluid looks healthy, I would assume your Trans is ok and look to a dash wiring short or bad connection as is the case with my C3.
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Check Trans is not a code the codes are flashed on the "Do Not Shift", here is what the books says since yours is working good
Check Trans light only
Vehicle drives normally
faulty Check Trans relay
faulty cab harness wiring
faulty ECU
faulty engine oil pressure switch
engine oil pressure low
when a ECU gets what called a cat eye the light will stay on and most folks don't replace the ECU just for that lol I have seen a lot of duck tape over the light.
A ? does the transmission have a retarder
iluvrbus
Yes the Check Trans light is the only one that stays on. Perhaps it is the check trans relay. I might have another one...I will put it in and check it. Thanks again
Ray