| Author | Message | ||
| Sean Welsh (Sean)
Registered Member Username: Sean Post Number: 505 Registered: 1-2003 Posted From: 67.142.130.16 Rating: |
Well, I've just come out of the Detroit/Allison shop, troubleshooting a TPS problem (turns out to be a bad wire, which we're going to have to disassemble half the bus to replace). While we were there, though, with the ECM out (and replaced, during the troubleshooting process), I worked on an old problem that has been with us since we bought the bus. The issue is that my DDEC-II ECM has no idea how fast I'm going. This isn't really a big deal, in that it does not affect operation of the engine or the coach. The built-in cruise control feature, for example, works just fine most of the time, based solely on engine RPM. It's a nuisance, though, because it means that my fancy SilverLeaf VMS engine display can not provide me some of the most basic and useful information: MPG, distance-to-empty, trip computer, and total engine miles. Way back in the beginning of our history with this coach, I ran the troubleshooting procedure for this all the way down to the step that said "Replace ECM." I stopped there, because ~$2K for an ECM was too much to fix a problem that only affects a cab display. Well, the ECM has now been replaced, and the problem is still there. I'm stuck now, because the next logical step is to replace the "Maximum Feature Throttle Interface," which is the black box that connects the DDEC-II ECM to the ATEC-1 ECU. This interface is not provided by either Detroit or Allison -- it is the responsibility of the "Vehicle Manufacturer," who, in my case, is out of business. The actual black box was made by KDS Controls of Madison Heights, MI, but I have no part number for them to track down, nor do they deal with individual operators. I also have no real evidence that there is anything wrong with this box. It seems to be doing the rest of its job just fine, translating the TPS signal from the DDEC into a TPS signal usable by the ATEC. So here's where I am at, and any help or suggestions would be appreciated: I have traced ATEC signal wire 205 (output shaft speed) from the ECU to the interface module, and the wiring checks out. I have traced DDEC signals wires 903 and 557 (VSS open-collector and VSS return) from the interface module to the DDEC ECM and these wires also check out. I don't have a scope, without which I am not sure how I can verify that the speed signal from the ATEC is actually present on wire 205 (suggestions welcome). I'm also not certain what the open-collector output from the interface module should look like in order to be the expected input to the VSS pins on the DDEC, or how to test for this without a scope. My DVM does tell me that pin 903 (VSS open collector) is putting out 5 volts from the ECM when the ignition is on (about the same as the signal voltage supply for all the three-wire pot-type sensors). Incidentally, the "schematic" for the Maximum Feature Throttle Interface is on page 3-27 of the Allison CEC-1 troubleshooting manual. Any thoughts? -Sean http://OurOdyssey.BlogSpot.com | ||
| PD3751-030 (Rdub)
Registered Member Username: Rdub Post Number: 5 Registered: 11-2006 Posted From: 209.47.87.2 Rating: N/A |
Hi Sean, I'm trying to remember the details of setting up my DDECIII/ATEC. Fortunately, it went well. The key is the interface so it sounds like you're on the right track. It's important you physically check the speed sensor on the trans since it is the most likely to incur damage of the components. Once you do that and a voltage/continuity check, I'd look for a spare interface to plug in to see if the problem lies there. I'm no expert, I've just done my own set up and, as I said, it went well so I don't have a wealth of troubleshooting backround to offer. Good Luck, Rdub | ||
| Pete/RTS Daytona (Pete_rtsdaytona)
Registered Member Username: Pete_rtsdaytona Post Number: 301 Registered: 1-2005 Posted From: 72.40.15.89 Rating: N/A |
Sean First here's what's inside that "little Black Box" (DDEC TPS to ATEC) -  secondly - I Think your going after the wrong VSS wire I believe DDEC 903 is a "open collector - DRIVER circuit - meant to DRIVE an electronic speedo and DDEC - 556 pin (E-2) Vechicle speed + and DDEC - 557 pin (E-3) Vechicle speed - are the actual wires from the atec tranny speed sensor 556 and 557 are usually used for cruise control input - but I understand that there may be an optional switch setting that allows the tach signal to be used instead - not sure DDEC switch settings to me are still a "BLACK ART" any questions call 386***672**0571 Florida Time Pete RTS/Daytona | ||
| Pete/RTS Daytona (Pete_rtsdaytona)
Registered Member Username: Pete_rtsdaytona Post Number: 302 Registered: 1-2005 Posted From: 72.40.15.89 Rating: N/A |
Sean Sent you the large size DDEC to ATEC black box pic via your BNO profile email addy Pete | ||
| Pete/RTS Daytona (Pete_rtsdaytona)
Registered Member Username: Pete_rtsdaytona Post Number: 303 Registered: 1-2005 Posted From: 72.40.15.89 Rating: N/A |
Sean You can test the output of the ATEC speed sensor by just connecting the 2 wires to an electronic speedo - (I can send you one for testing if you need one - and you can return it after your done) (I sell salvage Monaco gauges) IIRC - the ATEC VSS signal is 12 pulses per revolution - set the speedo's pulses / mile to 500=(approx tire revs / mile for 22.5 tires) times rear axle ratio (4.00 ??) times 12 pulses / tailshaft revolution equals --> 500 x 4 x 12 --> 24,000 pulses / mile you should get something close to your speed Pete RTS/Daytona | ||
| Bill Gerrie (Bill_gerrie)
Registered Member Username: Bill_gerrie Post Number: 65 Registered: 3-2006 Posted From: 209.50.73.48 Rating: N/A |
Sean The throttle interface module can be purchased at DMR Electronics INC 1111 East 7th Ave Hibbing MN 55746 Phone 218-262-6693 I bought one for my DDEC IV /ATEC. They have a full featured one for use with cruise at approx $90 as well as one that is basic for about $50. If you think the problem is the interface control give them a call and tell them how many wires are on yours. Bill | ||
| Ray Lala (Rayshound)
Registered Member Username: Rayshound Post Number: 86 Registered: 8-2003 Posted From: 68.201.216.135 Rating: N/A |
Bill, Thanks, I've been trying to find this max feature interface for the last 6 months. I am hooking a ddec4 series 60 to a 748-htb ATEC. Like Sean has referenced the page # etc in the DD manual. DD has not heard of one even though I brought them their manual. They wanted a part #. I have delt with DMR in the past, good people to deal with. Ray | ||
| dick egler (Dickegler)
Registered Member Username: Dickegler Post Number: 22 Registered: 8-2005 Posted From: 66.82.9.90 Rating: N/A |
Hi Sean, the atec 205 wire is a square wave output 0-5 volts. according to installation manual for ddec2, the 205 should be connected to the 556 wire from the ddec. the 903 is not used in this case. I believe that you have to enable vss input using prolink. i've been installing ddec6v92 with B400 in an eagle. just finishinsg up now. chasing some of the same things.i haven't road tested the cruise yet, but i think its right. i have the ddec2 install manual and trouble shooting manual, and would be glad to copy any pages you might need. Hope it helps dickegler | ||
| dick egler (Dickegler)
Registered Member Username: Dickegler Post Number: 23 Registered: 8-2005 Posted From: 66.82.9.90 Rating: N/A |
Sean, had anothe thought. have you tried allison technical support? I called the corporate switchboard (8-5 hours) and they connected me to tech and was able to get my question answered. worth a try? 317-242-5000 indianapolis, in | ||
| Sean Welsh (Sean)
Registered Member Username: Sean Post Number: 507 Registered: 1-2003 Posted From: 67.142.130.27 Rating: N/A |
OK, now I am really confused... Two people have now told me to use the 556 input rather than the 903 input to the DDEC. Yet manual page 3-27 of the ATEC book clearly states the Max Feature interface is an Open-Collector type interface, which the DDEC book shows as coming in on pin 903 (and the ATEC book, after updates, shows as leaving on 903). Futhermore, the harness is currently wired (I believe from the factory) to wire 903. Is my documentation wrong? I'd hate to swap pins at the ECM and end up damaging either the ECM or the interface module. Pete -- thanks for the drawing. I can tell you, though, that's not what I have. First off, the Max Feature box has six wires from the DDEC side, and five wires from the ATEC side, for a total of 11. (I know that two of these are power and ground from the DDEC, to power the module electronics, see below). Second, I've opened the thing up, and there is, in addition to resistors and capacitors, a LM2917N chip inside. That's a frequency-to-voltage converter circuit. It's a multi-layer board, so I can't trace all the wires, which means I can't tell if the 2917 is converting the speed output from the ATEC to a voltage input for the DDEC, or it's converting the tach output of the DDEC to a range-inhibit signal for the ATEC (both things happen in a Max Feature Interface). I believe the circuit you sent me is the "Basic Throttle Interface" described on page 3-26. The throttle position signal from the DDEC, in my case, is definitely arriving at the module on only one wire, wire 908 (PWM#1). So my interface is converting a pulse-width value to a voltage for the ATEC TPS. I know the ATEC is getting good signal here, so that part of the interface is working. I may call you tomorrow to discuss. As far as testing the speed output signal with a speedo, should I connect that between 205 and ground? (The output on 205, BTW, is 16 pulses per rev.) Bill -- thanks for the pointer, I will give them a call and see if they have a replacement for my box. It's worth $90 to me to find out if my box is bad, before I pull any more hair out swapping ECM pins (my ECM is incredibly hard to reach). Of course, to even test this (or any other theory), I need to find someone with a Pro-Link, since I have the VSS disabled in the ECM right now. (Since there is no input, if the feature is enabled I will get a Check Engine, Code 54 after a minute or two of driving, and my cruise will not work). To test anything, I need to re-enable the VSS feature. -Sean | ||
| Sean Welsh (Sean)
Registered Member Username: Sean Post Number: 510 Registered: 1-2003 Posted From: 67.142.130.43 Rating: N/A |
Thanks, everyone, for the follow-up. Here's where I am now at: I spent a little more time with the black box. The frequency-to-voltage converter chip, it turns out, is counting tach pulses from DDEC wire 505, and turning them into an on/off signal (not sure at what rev, though, without scoping it) to be fed into the ATEC on wire 222. This wire is used by the ATEC to inhibit certain shift ranges at certain engine RPM. Wire 908 from the DDEC, which is a pulse width signal that carries the TPS value, is merely fed through a set of resistors and diodes directly to the ATEC on wires 106A, 104, and 124. That leaves my problem area, which is wire 205 coming out of the ATEC. This is a square-wave pulse, 16 pulses per rev, representing the output shaft speed. Incredibly, the black box does nothing at all with this signal except pass it directly to the DDEC on BOTH wires 557 and 903. And herein, I think, lies my problem. I can't see how the DDEC will get any speed information at all if both of the sensor wires are shorted to each other, no matter what signal from the ATEC is tied to them. So here's my new question: From the open-collector circuit diagram in the DDEC book, it looks like 903 and 556 should be tied together, and the speed input should then come in on 557. Should I just disconnect 903 from the interface and see if it works? Will the DDEC pick up a pulse from the ATEC without a dedicated signal return path? I definitely need to find a Pro-Link to do any further testing... -Sean | ||
| Bill Gerrie (Bill_gerrie)
Registered Member Username: Bill_gerrie Post Number: 68 Registered: 3-2006 Posted From: 209.50.73.43 Rating: N/A |
Sean The way my max feature throttle interface is hooked up (works perfect) is as follows wire 222 direct to ATEC box from module. wire 205 direct to ATEC box from module. wire 124 direct to ATEC box from module. wire 104 direct to ATEC box from module. wire 106 direct to ATEC box and shield for transmission speed sensor as well as going to pin P on the transmission. wire 908 direct to DDEC box from module. wire 556 direct to DDEC box from module. 557 N/C. wire 505 direct to DDEC box from module. wire 953 to DDEC dedicated ground circut. wire 439 to DDEC dedicated + 12 volts. Hope this is of some help to you. Bill | ||
| Sean Welsh (Sean)
Registered Member Username: Sean Post Number: 511 Registered: 1-2003 Posted From: 67.142.130.34 Rating: N/A |
Bill, What I really need is help with is the innards of the module. My wires match yours, except for 556, where I seem to have both 903 and 557. Is your engine a DDEC-II, and what tranny do you have? -Sean | ||
| Richard Bowyer (Drivingmisslazy)
Registered Member Username: Drivingmisslazy Post Number: 1820 Registered: 1-2001 Posted From: 75.108.87.29 Rating: N/A |
I definitely need to find a Pro-Link to do any further testing... -Sean Sean, One listed here on the board for sale. Richard (Message edited by drivingmisslazy on February 04, 2007) | ||
| Sean Welsh (Sean)
Registered Member Username: Sean Post Number: 512 Registered: 1-2003 Posted From: 66.82.9.56 Rating: N/A |
Thanks for the pointer, Richard. I should have been more clear: I need to borrow or rent a Pro-Link for this. I have no desire to own one -- for daily driving, my VMS display gives me all the DDEC information I need. But it's read-only; I can't use it to set parameters in the ECM. Also, my transmission is old enough (ATEC-1 aka CEC-1) that it's not compatible with any Pro-Link (you need the dedicated Allison hand-held reader, or 6.x of the DOC software with the special Allison CEC adapter, and even then, my tranny can only be reprogrammed by reflashing the chip). The one for sale on the board, BTW, will not work with my old DDEC-II ECM. There have been a few on eBay, but I'd be looking at over $1,000 to own one of these, and I really just need to set one parameter on and off a few times until I get this working. We're going to be in southern AZ a little while longer -- if anyone in the area has a unit with the DDEC-II cartridge that we could borrow or rent, drop me a note. -Sean | ||
| Bill Gerrie (Bill_gerrie)
Registered Member Username: Bill_gerrie Post Number: 70 Registered: 3-2006 Posted From: 209.50.74.32 Rating: N/A |
Sean My engine is DDEC IV with the V731 ATEC. It is CEC-1 also. The module is the same one on DDEC II III IV. The 903 isn't used. The module has a place for it. The 556 is veh speed sensor + and the 557 is veh speed sensor -. My 908 is PWM #1 output. I don't have a DDEC II installation manual to cross reference the wires. Bill | ||
| Mark Renner (Boomer)
Registered Member Username: Boomer Post Number: 30 Registered: 11-2006 Posted From: 12.180.53.193 Rating: N/A |
Sean, if you were up here I could borrow my old Pro-Link and DDECII cartridge and loan it to you......but, coulda, woulda, shoulda. Good luck down there. Mark | ||
| Sean Welsh (Sean)
Registered Member Username: Sean Post Number: 527 Registered: 1-2003 Posted From: 67.45.244.133 Rating: N/A |
Solved! Well, here's the final answer: The tailshaft output speed signal comes out of the ATEC on wire 205, and this is to be connected directly to BOTH wire 903 and wire 556 on the DDEC-II. 557 is to be left unconnected. In my case, my 556 and 557 wires were shorted together someplace in the harness. I could not find where -- it's buried someplace deep in the coach. However, simply clipping 557 back at the ECM solved it, and my VSS input is now working perfectly. My next challenge is to figure out why, now that the speed signal is working right, my SilverLeaf VMS200 is still not showing mileage accruing on the trip meter. (Engine hours are also not incrementing, so something else is amiss.) Thanks, everyone, for all the help, and especially Sammy, who sent me copies of the relevant electrical print pages from, ahem, an unnamed coach builder, which ultimately led to the final solution. -Sean | ||
| Hans (Buellhans)
Registered Member Username: Buellhans Post Number: 13 Registered: 2-2007 Posted From: 205.250.41.167 Rating: N/A |
Hey just food for thought someone here said that the atec is 0-5 volts ,Not , the ecm for dedec is 0-5 the atec is from 5-0 volts well really the ecm is from .01 to 4.9 volts for the engine and 4.9 to .01 that way they can talk to each other just fyi |
