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Joe (Frtnkr)
Posted From: 71.49.37.116
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Votes: 0 (Vote!) | | Posted on Thursday, July 06, 2006 - 12:13 am: | |
This is sort of a continuation of this topic http://www.busnut.com/bbs/messages/11/14010.html?1151763006
We are talking about an 87 Flx Metro w/ 6V71 Turbo and V731 Allison. Engine is NOT DDEC.
We have power at the transmission plug and power at the shift select pad but the shift pad cannot tell the transmission to do anything. The only thing in between is the Transmission Electronic Control Unit. So question is...Do we need to change the Trans ECU when we change the transmission or are they universal? Or do we do we need to get a Detroit/Allison Tech out to reset something, say a prayer, or kill a chicken?
We have a wiring diagram coming our way thanks to a super generous busnut, but i thought I would put this to the rest of you all and see what we can see. |
Greg Peterson
Posted From: 71.228.18.37
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Votes: 0 (Vote!) | | Posted on Thursday, July 06, 2006 - 1:13 am: | |
Joe as I said in the old post you need to read the fault codes out. I put an Allison 1000 in my RV in place of a mechanical AT540. It was a #@&$ to make it happy so that it would go into gear. I needed the manual for the codes and had to take the computer over to an Allison Distributor several times to read the codes. As I fixed one problem another fault would show up.
The computer looks at the solenoids to see if they are short or open. It looks at speed sensors and all kind of other stuff. If you have a loose wire or bad connection on any of these things it will not go into gear or will go into limp mode. Since you have a different tranny than the original you may have a solenoid pack problem or sensor problem that did not exist on the old one. If you look at Allison site for service publications you will see that there is different V731 listed some that are all electronic and some that are Hyd over electronic.
On my 1000 I had put in an older rebuilt unit that did not have a recirculation solenoid that was added after 2003. The computer when first powered up was supposed to detect that it was not there and ignore it. It never detected it correctly and it thought I had an open solenoid. The local Distributor finally got in touch with “the man” that wrote the program. He said pull the wire out of the harness that went to that solenoid and it would ignore it. It never worked so I put a resistor on the computer to simulate the solenoid and all is now happy. Of course their engineers said that would not work but it has worked perfectly from freezing winter to hot summer.
I boar you with this long story to make the point that without reading the codes you will have more luck pushing a rope than fixing your problem. |
Joe (Frtnkr)
Posted From: 71.49.37.116
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, July 06, 2006 - 1:54 am: | |
Greg, sorry to make you type so much, you dont bore me at all though. We have been trying to avoid getting the Allison guys to come out to the shop because they charge $90/hr. We figgured that we would try and cover all the bases before we got them out.
The manual says that there is a switch below the shift control pad that when activated will show a blink code but we have been unable to find it.
I run a Mac laptop so I am assuming that getting the software for it is not going to happen and the shop doing the work does not have any allson programs either. Any ideas?
The transmission we installed is the same variety as the one we pulled out, if that makes any difference. |
Greg Peterson
Posted From: 64.238.49.65
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, July 06, 2006 - 11:16 am: | |
Joe take the computer box off the bus and go to an Allison distributor. Look on the Allison web for a list of distributors that are close to you. For example in Chicago it is Inland DD and Allison, You need the distributor because they have more data and connections with Allison than a service shop. If you take the computer to them and talk nice they may read out the error codes for free.
They did that for me free and I went back many times but looked like and old desperate man so they helped me out. They also have all the manuals that tell you what the code means and what to do to fix it. If you take it over there you will not have the cost of a service call and will get some idea of what the computer does not like.
Good luck |
Joe (Frtnkr)
Posted From: 71.49.37.116
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, July 06, 2006 - 11:36 am: | |
Greg, now you are speaking my language, any post with the word "free" in it can't be all bad.
Any ideas where I could locate the computer box on a V731, are we talking about the ECU? I will look at the manual today and see if I can find anything there.
Thanks again, Joe |
Joe (Frtnkr)
Posted From: 71.49.37.116
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, July 06, 2006 - 4:24 pm: | |
Just returned from the shop. I followed the process listed in Appendix F of the Allison V731 troubleshooting manual for getting the "check trans" light to flash a code and it will not flash a code.
Can I get the ECU tested by removing it from the bus and taking it to an Allison distributer like you mentioned with your computer? Or are we going to have to get a tech to come to the shop?
We will have a complete wiring diagram soon and we are going to double check everything that was disturbed in the engine/trans swap and then get into the computer stuff, unless someone has a better idea... |
Greg Peterson
Posted From: 71.228.18.37
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, July 06, 2006 - 7:06 pm: | |
Hi Joe,
Yes you can take the ECU to the Allison distributor and they should have a test box that will check the ECU (or TCM Allison calls it a transmission control module) and read out the fault codes. This will be your cheapest thing to try first. As I said before they did this for free at the distributor that is near me.
Now that you have a schematic you should double check you’re wiring. The fact that you cannot get the ECU to flash the code out does not seem good. If you cycle the ignition or power does the check transmission light come on immediately or does it take a few seconds? Does the light stay on continuous with the power on? If the light is on that means there is at least one fault code in the ECU.
Some faults will clear when the problem is fixed. they will go from active to inactive,
There are some faults that have to be cleared by the Allison test program. If you put bigger injectors in the engine you should have the Allison guys reset the ECU to fast learn mode. It will relearn the optimum shift points fast and then slowly fine-tune them in as you drive. If you change the engine HP without doing this the ECU will take a long time to converge on the optimum shift points if ever.
The test tools and software you need is best left to the Allison distributor. You can buy the software for some $$$ but they will not sell it to you unless you have a certificate to prove you took one of their special classes on how to use it properly. The class was several days as I recall and that is what cost the most money.
Good luck Joe.
You can just imagine how much fun I had when I replaced a mechanical transmission with an all electronic one. I had to build all those wiring harnesses from scratch. I really liked it once I got it all working. On the way to that point I had to learn some new cuss words. |
Joe (Frtnkr)
Posted From: 69.139.108.230
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, July 06, 2006 - 8:55 pm: | |
Cuss words to discribe cuss words I would imagine. Much respect for taking on all that work and getting it done. I hope you didn't keep track of all those hours...
The transmission idiot light stays on as long as the engine is running. If the engine is off but "day run" is selected, (day run is like when you turn the key on a car so the lights and radio work but don't turn it over to start) all dash lights come on for a moment and then go off, including the trans light.
I'll talk to Covington Detroit tomorrow and see if they are willing to help, they have been helpful in the past and I have bought enough stuff up there that they know me when I walk in.
I'll keep you all posted on what I find out. |
Joe (Frtnkr)
Posted From: 71.49.37.116
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, July 07, 2006 - 3:07 pm: | |
Covington Drtroit could not read the codes with the ECU out of the bus. They said it is a forst generation unit that has to be checked on the bus.
They gave me a few other things to check but if none of them work I'll get it towed up there. |