Engine/Transmission (1998.5 - 2002) Anatomy of an APPS

[rweis]

Gary,



You have 4 hotmail pictures (1. 5 MB @) of my APPS (cruise control and auto transmission). Pics too big to post on TDR.



Timbo,



A little resistance here, a little resistance there, maybe series (adds), maybe parallel (subtracts). Just have to see what works.



Bob

 

[Gary - K7GLD]

Gary,



You have 4 hotmail pictures (1. 5 MB @) of my APPS (cruise control and auto transmission). Pics too big to post on TDR.



Timbo,



A little resistance here, a little resistance there, maybe series (adds), maybe parallel (subtracts). Just have to see what works.



Bob

Got the pics Bob, EXACTLY what I needed!



Looks a bit tight at the lower side of the bracket, but looks like what I have planned will fit OK with only minor re-arranging from what I had planned.



Now all I need is all my parts! :-laf

 

[rweis]

Oo. Oo. Oo. Oo. Oo.



I have 1 code left 0121 TPS voltage does not agree with ECM. Batteries are disconnected right now!!!!!!!!!!!!!!!!!!!!!!



I have the bus APPS in, only had to add 1@ 100 ohm resistor to it to get the C3 pin 23 volatge just about dead on to the DC APPS (. 600 V).



I took the C# pin 23 readings from idle to 2500 every 125 (the tick mark on the engine speed dash), and compared it to timbo's before I changed the APPS. The voltages were a little different, but the shape of the curve (straight line) was exactly dead on.



As I understand the fix for the 0121 is disconnect the batteries for 30 minutes. Reconnect the batteries. Key on, APPS to the floor slowly and up slowly 1 time (SM 14-97 ECM Calibration). This recalibrates the ECM to the "new" APPS.



IF it works and I can get engine acceleration, we have a winner.



Bob Weis

 

[rweis]

Well, Pilgrim, NOT so fast! :{ :{ :{



I do not have the IVS voltages right. Did some measuring of the DC APPS and will get the bus APPS to "be like them". Will take a day or two to get the parts gathered, and have a few commitments this week that will slow things down some. However, I can smell it getting really close.



We can always use Gary's plan for the IVS using a microswitch if I can not get the APPS IVS to cooperate.



Adding the 1@ 100 ohm resistor to the bus APPS (APPS ground side) made it so close to the DC APPS it was amazing.



Just have to duplicate the IVS voltages.



Bob Weis



I did learn something today. When I had the bus APPS in, I have a Smarty and use it to clear codes. Eventhough it says it cleared the codes it may not. I think that tells you that the problem is more than just a code, ie it is a basic fundamental problem. When I put the dc APPS back in and cleared the codes witht he Smarty it did clear the 0121 and it stayed cleared. I think that will be the signal that the fix is correct is when the Smarty does clear the 0121 with the bus APPS in the circuit.

 

[Gary - K7GLD]

Here's some points to ponder:



To me, the primary "trick" here, is to come up with a relatively low cost replacement that is easy to duplicate with fairly common tools and hardware store parts, other than the potentiometer and IVS switch themselves - and those should be reasonably easy to obtain as well.



Added to that, is the requirement that whatever IS developed, be easy to maintain and troubleshoot - and be AT LEAST as durable and reliable as the DC APPS we are trying to eliminate/replace.



A "solution" that is too complicated and/or difficult to reproduce - or perhaps still too expensive for those who consider it more an experiment than a proven "fix" is just wasted effort and materials!



This has been an educational thread so far, one that started with what appeared to be an insurmountable problem, as far as reasonable alternatives were concerned - but we've come a long ways! Oo.



At this point, I'm at a bit over $25 for a potentiometer, a microswitch and a plug. There's some engineering and fabricating to be accomplished, but so far, that looks pretty easy - but things often CAN be deceiving, eh Bob? :-laf:-laf

 

[rweis]

So far I have $100 in the bus APPS (orderable from several sources) & $0. 75 in 1@ 100 ohm 1 watt resistor (RadioShack).



The connectors are extra because you can solder or crimp it directly into the dc wire harness. I will provide a wire map from the bus APPS to the dc wire harness, ie which wire from the bus APPS is connected to which other wire in the dc wire harness.



The mounting has zero adjustment, so it is a remove and replace and tighten the screws.



I think the remainder of the resistor puzzle will be a couple of more resistors at $0. 75 each.



Total cost should not go over $103. No mechanical modifications (drilling etc) at all. Longevity I do not know.



Everything I have done with a 10mm wrench to get the APPS bracket off and on, a torq (#25) screw driver to get the APPS off and the new APPS on, and wire connectors to map the bus APPS to the dc wire harness and install inline (series) resistors.



Good remimder of the perspective of solution though.



Bob Weis

 

[KarlC]

For those of you who have Excel or Openoffice, I made up a spreadsheet to compute the resistors required in the ends of a pot used to simulate the operation of the APPS. The spreadsheet is located here: APPS_Calculator. xls There are six things you will need to enter into the spreadsheet...

1. The overall voltage applied to the APPS circuit -- 5 volts.

2. The resistance of the pot you intend to use.

3 & 4. The limits of the mechanical range of your pot that will be used. That is, if your setup will turn the pot from 10% to 80% of its mechanical range, enter 10 and 80.

5 & 6. The desired idle and WOT voltages.

The spreadsheet will compute the resistors that will have to be put in the ends of the pot to get the desired range. If either or both of the resistor values come out negative, you've entered a set of conditions that can't be met. By playing with it you can find what will work and what won't.



I just whipped this up this morning and it's kind of rough. if you have any suggestions please let me know and I'll change it.



Karl

 

[KarlC]

I do not have the IVS voltages right. Did some measuring of the DC APPS and will get the bus APPS to "be like them". Will take a day or two to get the parts gathered, and have a few commitments this week that will slow things down some. However, I can smell it getting really close.

Just have to duplicate the IVS voltages.

Is it possible that the idle side of the pot on the bus APPS is internally connected to the IVS switch as well? If so, putting a resistor in series with the idle side might affect the IVS output too. It might be that the people who designed the bus APPS assumed that the low side of the pot and the low side of the IVS switch would both be grounded so they connected them together.

 

[rweis]

I do not know. I need to get a lot smarter on EXACTELY how the IVS works, the sequence, what to expect, and exactely what the IVS does that allows the ECM to accept engine acceleration (and what the ECM is looking for in the way of parameters to allow engine acceleration).



After I could not get the IVS to work I put my dc APPS back in and took several measurements of power off, power on, engine running, and as many things as I could to help make sense of and clarify the direction to proceed.



I'm almost thinking that the bus IVS may have such different paramenters and be intergral to the APPS function that it may not be useful at all and I need to provide the IVS function through some other means other than the bus APPS IVS. That is a last resort though.



I have not counted the bus APPS IVS out, but will have to puzzle this through which may take some time.



I do not know how the internal circuit of the bus APPS interelates with the IVS if at all.



I was really pleased that I could exactely duplicate the dc APPS voltages with the bus APPS, which I thought were going to be the hardest part. However the IVS switching and voltages is turning out to be the conundrum. I just need to be more diligent and cautious with the approach.



Where there is a will there is a way, and there certainly is a will.



Bob Weis

 

[FLynes]

I sincerely admire all the work that has gone into this endeavor, and I hope that there is a financial benefit to this, but I wonder if there's a DC engineer, who could give you all the answers in one fell swoop, reading this thread and laughing to himself about the wheel being proverbially reinvented.

 

[rweis]

Well, the thread is only about 4 years old, seems like he (she) might have chimed in by now, but who knows.



Bob Weis

 

[KarlC]

There seems to be a wealth of info about this at Google patents. A patent describing the Williams device is here here
And This one describes how the mechanical travel of the pot is limited to less than its full range.
To get there I searched Google patents for "accelerator pedal position validation"

 

[Gary - K7GLD]

GUYS, as far as I can determine - aided by Karl's pointer to the IVS part of the above patent pointer - is the the primary point of the use of the DC solid state IVS as part of our Cummins APPS, is purely as a means to provide a means of idle/off-idle sensing that is maintenance free and no adjustment needed - OR POSSIBLE!



As long as there is no need or objection to manually adjust the idle/off-idle function, there is absolutely NO problem with doing it with some sort of mechanical switch, rather than electronically. A switch is certainly simple and easy, both in operation, and in installation. There's nothing wrong with doing it electronically either - as long as the circuitry used is reliable and durable.



I suspect ours is NOT, at least as far as construction goes - and I further suspect that a large percentage of APPS failures is NOT because of the potentiometer section, but rather because of the IVS circuitry and the lousy method used for the membrane circuitry traces to make contact with the pins of the connector.



Sure, eventually the potentiometer WILL fail, but I doubt that is the largest reason for APPS failures by a LONG shot! I'd bet that either of the pair of used/replaced APPS modules I have, could be carefully disassembled, the IVS portion carefully removed and mounted to a separate small base/enclosure with SOLDERED connections - and function perfectly - either with the original potentiometer section, or with an appropriate substitution pot.



I have carefully measured several used, supposedly failed APPS units - and every single one measured essentially the same resistance values, with no dead or erratic spots that I could detect - and I have some pretty decent measuring equipment.



SO, if the potentiometer section is OK, what DID create or simulate their failure?



IF the major reason/excuse for using a solid state logic/switch for APPS operation is freedom from adjustment and simplicity of replacement in terms of time and labor, I'd as soon convert over to a purely mechanical device that is far less complicated and expensive - and probably far easier to adjust than many other things on the truck...

 

[KarlC]

IF the major reason/excuse for using a solid state logic/switch for APPS operation is freedom from adjustment and simplicity of replacement in terms of time and labor, I'd as soon convert over to a purely mechanical device that is far less complicated and expensive - and probably far easier to adjust than many other things on the truck...

Gary, I agree with everything you're saying. I think one major reason DC and the other auto makers are going electronic with everything they can is cost. The DC APPS is probably built by automated assembly machines overseas, and think how many of them they can put in one container on a ship. They then have one part to do TPS and IVS, and still have redundancy. The Society of Automotive Engineers (SAE) has a standard, J1843, for APPSes. It's $59 but I don't think it would help that much.



I think we're well on the way to getting something to fit our needs.

 

[timbo]

Here's some points to ponder:



To me, the primary "trick" here, is to come up with a relatively low cost replacement that is easy to duplicate with fairly common tools and hardware store parts, other than the potentiometer and IVS switch themselves - and those should be reasonably easy to obtain as well.



Added to that, is the requirement that whatever IS developed, be easy to maintain and troubleshoot - and be AT LEAST as durable and reliable as the DC APPS we are trying to eliminate/replace.



A "solution" that is too complicated and/or difficult to reproduce - or perhaps still too expensive for those who consider it more an experiment than a proven "fix" is just wasted effort and materials!



This has been an educational thread so far, one that started with what appeared to be an insurmountable problem, as far as reasonable alternatives were concerned - but we've come a long ways! Oo.



At this point, I'm at a bit over $25 for a potentiometer, a microswitch and a plug. There's some engineering and fabricating to be accomplished, but so far, that looks pretty easy - but things often CAN be deceiving, eh Bob? :-laf:-laf

Right now the way i see it we are all MOTIVATED people trying to LEARN how this works and come up with a working APPS!! Research and development costs money. Ask BOB, he just spent 100 bucks for a bus APPS that might not work, BUT IT MIGHT and he willing to share that information with all of us!! As of right now i have only invested about 50 bucks and some time. Time that could have been spent coming up with useless "Recliner theory,"or is that what it really is?

So at what point do we consider a $25 pot and microswitch, and some hardware store parts a "PROVEN FIX" for a precision sensor that costs 400+ dollars? Sounds like you are bragging about how cheap you can do it, but it is not COMMON to have QUALITY and CHEAP go together!WE ARE ALL IN THE LEARNING PROCESS RIGHT NOW!

THE WAY I SEE IT, THE MAIN OBJECTIVE AT THIS POINT ,IS TO GET A POT AND A MICROSWITCH TO WORK UNDER NORMAL DRIVING CONDITIONS,SMOOTHLY WITHOUT SETTING CODES! UNTIL THAT IS DETERMINED, THIS COULD ALL BE A "WASTE OF EFFORT AND MATERIALS" BUT THERE IS ONE THING THAT WE WILL ALL GAIN, EVEN IF THIS DOES NOT WORK , AND THAT IS KNOWLEDGE, WHICH IS PRICELESS!!!!!!! USAULLY LEARNING IS NEVER FREE!!!!!!

 

[rweis]

..... the primary point of the use of the DC solid state IVS as part of our Cummins APPS, is purely as a means to provide a means of idle/off-idle sensing that is maintenance free and no adjustment needed - OR POSSIBLE!



It is the OR POSSIBLE part that is the kicker.



I'm starting to agree with Gary that the IVS function is the weak link and needs to be replaced with a mechanical switch system.



In rewiring my dc APPS harness I have seperated the APPS wiring from the IVS wiring. Using the dc APPS or the bus APPS as the APPS, and a mechanical switch as the IVS would work for me. AND just maybe that is the crux of the problem as Gary has been saying.



The "fix kit" would to be remove the IVS signals from the dc APPS and install a mechanical switch to do the switching.



Gary think you can find a switch (or two?) that will fit in the mechanical space and function electrically correctly?



Bob Weis

 

[rweis]

Gary,



What do you think about using 2 OMRON D2VW-5L1B-1MS Long Lever, with wire leads, mounted side by side (total package width . 82") over in the area where the TV cable for us ETC folks connects?



The idea is to use 1 switch for each function of idle and throttle. The mounting would be to a 1 1/2" long piece of 1" angle aluminum that is slightly bent from an 90* angle to about 125* (guess) angle and the aluminum piece is bolted vertically to the frame of the APPS where the WOT triangular web is.



The micro switches are good for 10,000,000 cycles and are watertight and dust proof.



The lever would contact the flat of the bell crank toward the central pivot from where the TV cable attaches.



I think there is enough room to mount 2 switches there and not have hardware interfearance.



The switches typically run about $7. 50 each.



This would give a guy with an APPS problem a way to try to keep his dc APPS and replace the IVS only for about $20 (2 switches and a little aluminum angle for mounting). The mechanicals of drilling the mounting holes for the aluminum switch mounting bracket should not be too bad by removing the grey APPS bracket to work on it.



Then if the dc APPS is still not functional and he has done the C3 pin 23 voltage alignment, he gets the Wilson bus APPS and replaces his dc APPS 1 for 1. If he has to go this far he has $120 in it vs the $400 from dc, but he has a totally new APPS and worked the repair in stages. The bus APPS is an exact mechanical fit. I found it needs a 100 ohm series resistor on the ground side to bring it up to . 6 volts over at C3 pin 23. The ECM seems to like it fine.



You are probably right in that it is the IVS circuits that can not handle the heat and vibration and are prone to failure (poorly / cheaply made comes to mind).



What do you (or anyone for that matter) think about this approach?



The more I think about trying to get the IVS of the bus APPS to match the dc ECM the more I think that approach is going to be difficult at best and you still have IVS electronics that you may not be able to depend on. Your comment about NO ADJUSTMENT is exactely right.



Bob Weis

 

[KarlC]

What do you think about using 2 OMRON D2VW-5L1B-1MS Long Lever, with wire leads, mounted side by side (total package width . 82") over in the area where the TV cable for us ETC folks connects?



The idea is to use 1 switch for each function of idle and throttle. The mounting would be to a 1 1/2" long piece of 1" angle aluminum that is slightly bent from an 90* angle to about 125* (guess) angle and the aluminum piece is bolted vertically to the frame of the APPS where the WOT triangular web is.

I think you only need one switch. The Omron part has both normally-open and normally-closed contacts built in, which should be all you need.

 

[Gary - K7GLD]

So at what point do we consider a $25 pot and microswitch, and some hardware store parts a "PROVEN FIX" for a precision sensor that costs 400+ dollars? Sounds like you are bragging about how cheap you can do it, but it is not COMMON to have QUALITY and CHEAP go together!WE ARE ALL IN THE LEARNING PROCESS RIGHT NOW!

I agree entirely - but suspect you are somewhat missing my basic point - and we dern sure do NOT want to start squabbing among ourselves as to which is the "best" method. :-{}



I'm sure those of us experimenting - and those just reading - would quickly agree that a CHEAP/simple solution that is UNreliable, is inferior to a more expensive/complicated one that IS reliable - within reason!



I was simply attempting to point out that while a scattergun approach is undoubtedly appropriate in the experimental stage, the final solution will be easiest accepted and put to use only IF it is reasonably inexpensive, and easily duplicated.



As to $$$ spent in research, I have well over $250 in tried, but unused, fuel system parts out in my garage - and similar tested but unused stuff covering the other efforts I have made in other areas of truck "improvement" - the final result of all those so far, ended up being totally reliable, easily duplicated, and at FAR less cost than commercial equivalents.



The $$$ I quoted earlier in this particular thread, cover only the parts I plan to actually use, after buying and inspecting others I probably will NOT use - such as the *3* potentiometers I have bought - but will only finally use one of! Same for switches - instead of buying single items, I usually buy several, to have backups in case of efforts and mods that render the first one no longer usable.



Yeah, experimentation DOES cost $$$ - and usually LOTS more than the final solution - and SOMETIMES, there IS no "final solution" worth using, and ALL that $$$ is wasted!



Been there, done that! :-laf



Will whatever we here end up with here REALLY be reliable and inexpensive over the long haul? Hell, who knows at this point? All we can do is keep experimenting, providing full info as to what EACH of us is attempting, and the results - that way we weed out what WILL NOT work from what WILL, and come to either a total failure - or a solution that matches the primary goal as nearly as possible - but WITHOUT a reasonable goal, all the $$$ and effort become pointless!

 

[Batphreak]

The Society of Automotive Engineers (SAE) has a standard, J1843, for APPSes. It's $59 but I don't think it would help that much.

Before anyone does anything rash, have no fear. I have this spec, I'll upload so everyone has access later this evening.