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

[Blackbird]

http://www.williamscontrols.com/products/index.cfm?fuseaction=throttle

http://www.williamscontrols.com/products/throttle_controls_catalog.pdf



Found this information as I was researching the APPS issue.

Could one of these controls be adapted to our use? I find the suspended throttle pedal that is used for the Cummins (Part # 131507) interesting. Could this be used with the manual trans? Sticks was talking about relocating the APPS to get it away from the engine. I would think that one could find one of these at used truck parts supplier for not much $$, and just screw it to the firewall and connect cables if we can tweak the values appropriately.



Jay

 

[Sticks]

Good find Blackbird!



Gary - what do you think?

 

[Gary - K7GLD]

WELL, I'm sure there are a number of similar devices that SEEM to function much the same as the APPS in our trucks - problem is, that without exact knowledge as to how circuit design and operation differs, we're shooting in the dark...



When/if we get an actual circuit diagram, it would be rather simple to fabricate a circuit board that duplicates the one inside the stock APPS, and then mount it in a convenient spot, and then wire it to a quality mechanical potentiometer that is of better construction than what we now have - none of the individual components inside the stock APPS seem to be proprietary or unusual/difficult to obtain - so duplication of circuit SHOULD be rather easy.



Substitution of an UNKNOWN device, on the other hand... .

 

[Sticks]

Well, they do put the 5. 9 Cummins school busses, and one of the links showed "School Bus application/Cummins"...



I suppose getting a hold of one who works on the busses, and ask him what the difference is other than the Mopar PCM/ECM.



Scot Bentz... Calling Scott Bentz... Please respond at your nearest white courtesy keyboard.

 

[Blackbird]

Are we barking at the right tree?

Originally posted by sticks

Likewise, getting the assembly away from the heat and waiting for the problem is another method, albeit more expensive ($55 for plug casings and wires - OUCH).

Sticks -



Were you able to get a plug casing that resembles the one on the APPS? If so where & P/N's would be appreciated. Or would you be willing to sell me yours & ship to me???



I just had a neuron fart (not big enough to call a brain fart ) and wonder if the issue isn't with the connection at the zebra strip, as Dave - 15w40 refers to it.



The symptoms that I had originally presented with the Cummins e-brake not engaging (I always use it, only turn it off if I have to set & idle for a couple of minutes and the hissing is offending. ) Things progressed to changing idle speeds, finally unresponsive throttle and codes 121 & 122, to e-brake cycling on & off at idle.



I bought Alex Pepper's OBD-II scanner that others recommend here on TDR and started observing the action.



Observations:



1. ) Minimum TP values did vary between throttle cycles

Range: 0-~10+, normally around 7. 8 +/-

If TP value > ~9, e-brake would not engage.



2. ) Several times when the throttle was unresponsive, TP

showed normal rise & fall with pedal movement, no change in

RPM's as pedal is moved. I do have scans of some

of these events and will search through them for a screen

capture if anyone is interested.



3. ) At other times when the throttle was unresponsive, there was

no change in TP value.



4. ) The problem seems to present itself more the hotter it is.



These observations lead me to question if the zebra stripe isn't the issue after all. If the connection @ the zebra strip is intermittent or shows increased resistance, this would change the values presented to the ecm/pcm giving symptoms like we've seen. It could also make the switch circutry malfunction to indicate that the throttle is @ rest even if it isn't (#2).



My thought is to hard wire directly to the film & bypass the zebra strip altogether and provide a connector to plug the wiring harness into.



This would test to see if the zebra strip is the issue because I could reinstall my 'bad' APPS and see if it shows any improvement.



Thought/comments?



Jay

 

[John - K5AWO]

Re: Are we barking at the right tree?

Originally posted by Blackbird

... . My thought is to hard wire directly to the film & bypass the zebra strip altogether and provide a connector to plug the wiring harness into... ... This would test to see if the zebra strip is the issue because I could reinstall my 'bad' APPS and see if it shows any improvement.

Jay,



I had the same thought but haven't voiced it yet. Using an external pot to substitute as the throttle would give some clues about the carbon trace being part of the problem.



The mechanical arrangement would be the most difficult part. Possibly tear up and old dial string radio to retrieve the string pulley on the tuner shaft? Wrap a spring around the shaft to make it pull back.....



Bridging the pot with an external resistor to get the "total" resistance value might be needed. The circuitry most likely is just reading the "voltage" at the arm.

 

[Blackbird]

Re: Are we barking at the right tree?

Originally posted by John - K5AWO

Originally posted by Blackbird

... . My thought is to hard wire directly to the film & bypass the zebra strip altogether and provide a connector to plug the wiring harness into... ... This would test to see if the zebra strip is the issue because I could reinstall my 'bad' APPS and see if it shows any improvement.

I had the same thought but haven't voiced it yet. Using an external pot to substitute as the throttle would give some clues about the carbon trace being part of the problem.

The thought that I was trying to express during my previous post was to disassemble the APPS that I just replaced enough to get at the edge of the "circuit board" film and solder wires directly to this, connect these wires to a plug that would connect with the existing wiring harness connector, reassemble & reinstall the modified APPS and see if the problem is resolved by bypassing only the zebra strip and leaving the existing carbon traces 'as is'.

The mechanical arrangement would be the most difficult part. Possibly tear up and old dial string radio to retrieve the string pulley on the tuner shaft? Wrap a spring around the shaft to make it pull back.....



Bridging the pot with an external resistor to get the "total" resistance value might be needed. The circuitry most likely is just reading the "voltage" at the arm.

This is what I was proposing to do with the used suspended throttle pedal. See previous post referencing Williams Controls.

Originally posted by Gary - KJ6Q

... When/if we get an actual circuit diagram, it would be rather simple to fabricate a circuit board that duplicates the one inside the stock APPS, and then mount it in a convenient spot, and then wire it to a quality mechanical potentiometer that is of better construction than what we now have - none of the individual components inside the stock APPS seem to be proprietary or unusual/difficult to obtain - so duplication of circuit SHOULD be rather easy.



Substitution of an UNKNOWN device, on the other hand... .

All I was suggesting was to use one of the throttle pedals, appropriately 'adjusted' to match the values of the APPS , as a test to see if heat was an issue.



As far as a circuit diagram, see attached image with copies from the Williams Controls catalog showing pin outs/wiring diagrams, and from the DC service manual wiring diagram.



Edit

Hmm... image wouldn't attach, must be doing something wrong.

Jay



In a previous post Dave(15w40) said that the only thing that the circuit was doing was replacing the micro switch... , yes it would be nice to verify that with his work on the re/eng of the circuit, but it looks like we're still comparing apples...



Jay

 

[Sticks]

Re: Are we barking at the right tree?

Originally posted by Blackbird

Sticks -



Were you able to get a plug casing that resembles the one on the APPS? If so where & P/N's would be appreciated. Or would you be willing to sell me yours & ship to me???



Jay

Jay - I no longer have the recipt that has the PN's for the plug. They are Weather Pak brand and they can be found at your official Cummins Distributor confused: I guess there is a difference between a Cummins shop and Distributor) Any how, they are listed in the Weather Pak Engine Harness Repair Kit. I will try to dig mine out of where ever I put them for safe keeping until I find out if I get to keep the truck to see if there are any numbers on them. The expensive part is the pin/wires at $3. 80 each... 12 of them.

 

[John - K5AWO]

John (me)... . Bridging the pot with an external resistor to get the "total" resistance value might be needed. The circuitry most likely is just reading the "voltage" at the arm. ... .

--------------------------------------------------------------------------------

Jay: This is what I was proposing to do with the used suspended throttle pedal. See previous post referencing Williams Controls... .





Thanks Jay for the comment. It seems I missed one of the posts. Didn't mean to repeat what had already been said. I had seen the post on the Williams controls and bookmarked it for later use. I had forgotten it was in this thread.



Image didn't attach: Most likely it is over 32k in file size. I had the same problem earlier.



-John

 

[Gary - K7GLD]

"Observations:



1. ) Minimum TP values did vary between throttle cycles

Range: 0-~10+, normally around 7. 8 +/-

If TP value > ~9, e-brake would not engage.



2. ) Several times when the throttle was unresponsive, TP

showed normal rise & fall with pedal movement, no change in

RPM's as pedal is moved. I do have scans of some

of these events and will search through them for a screen

capture if anyone is interested.



3. ) At other times when the throttle was unresponsive, there was

no change in TP value. "



HMMMmm - if the above readings proved to be typical, sure would seriously impact the theory that improper function of the APPS potentiometer section was a primary suspect... Altho' it HAS been established that the poor internal circuit film-strip connection at the APPS connecting pins might be strongly contributing to erratic APPS function. Might be worth looking into a decent method of providing a more positive internal connection to those pins, but sure would be a chore for most owners...

 

[Blackbird]

Originally posted by Gary - KJ6Q

HMMMmm - if the above readings proved to be typical, sure would seriously impact the theory that improper function of the APPS potentiometer section was a primary suspect... Altho' it HAS been established that the poor internal circuit film-strip connection at the APPS connecting pins might be strongly contributing to erratic APPS function.

Yes, that is why I reported this.

Originally posted by Gary - KJ6Q

Might be worth looking into a decent method of providing a more positive internal connection to those pins, but sure would be a chore for most owners...

Agreed. This is why I was asking sticks if he remembered Part #'s for the parts he got to try to relocate the APPS.

Are there any of those 'bad' APPS's still available? I don't need one that is complete, I want to look at the location of the film->zebra strip->pin location. If one is available with this section I would like to take a look at it to see how difficult it is to access that area.

Originally posted by sticks

The expensive part is the pin/wires at $3. 80 each... 12 of them.

I was only thinking of 6 and the female portion of the plug that matches the sensor body.



Jay

 

[Gary - K7GLD]

Jay, that area is pretty much impossible to get to without totally destroying that part of the assembly - not that that is a particularly bad thing, if an alternative IS possible - dunno what difficulties might be involved in soldering or otherwise direct-connecting to the circuit surface itself - here's the best pic I have available showing the circuit traces on the film running back towards the pins:

#ad




One of the guys here has the unit shown, and discovered the rather poor method the APPS maker used to make contact to the pins - maybe he could try careful soldering direct to that film to see if it's do-able, and let us know - I hate to destroy another potentially salvagable APPS if I can avoid it...

 

[Blackbird]

Originally posted by Gary - KJ6Q

... I hate to destroy another potentially salvagable APPS if I can avoid it...

Agreed. That was why I worded my request as I did:

Originally posted by Blackbird

Are there any of those 'bad' APPS's still available? I don't need one that is complete, I want to look at the location of the film->zebra strip->pin location. If one is available with this section I would like to take a look at it to see how difficult it is to access that area.

If I was going to try and modify the one that I removed as 'bad' from my truck, I would like to look at one that is already in pieces so that I would have a chance of not destroying it.



Jay

 

[Blackbird]

Still having problems attaching images, which is OK for now. By the time I shrank the image that I was trying to attach enough to get under the 32K size limit it was unreadable. For now if your interested, look at the pin out/signal diagrams in the Williams Control catalog and compare to the one in a DC service manual, or the one that someone posted on one of the Anatomy/Autopsy of APPS threads.



Jay

 

[Gary - K7GLD]

Actually, as I look at the pic above, it wouldn't seem all that hard to simply remove the cover as I did on that unit, and then carefully expose the traces on the film and carefully solder right there - then provide a hole in the removed cover for the leads to exit, thus totally abandoning use of the stock connecter, replace and seal the cover and the access hole - solder the wires to the appropriate new male plug, and away ya go!

 

[Blackbird]

Originally posted by Gary - KJ6Q

Actually, as I look at the pic above, it wouldn't seem all that hard to simply remove the cover as I did on that unit, and then carefully expose the traces on the film and carefully solder right there - then provide a hole in the removed cover for the leads to exit, thus totally abandoning use of the stock connecter, replace and seal the cover and the access hole - solder the wires to the appropriate new male plug, and away ya go!

Yes, that is along the lines that I was thinking of. Probably easier too. I was thinking of trying to use Dremel to cut groove into case to pull film through & work from there or drill small holes over film @ proper locations & use a pin type device to pierce film & connect to circuit with connections made to the pins.

Only thing that would need to know is which trace goes to which pin in the connector.



Jay

 

[Weidner]

option to williams controls...

I know that some of the new BMW's "99-01 3. 0 x5 for sure" use a tps (apps) built on to the throttle pedal. They offer one for manual and one for auto, the auto one has a notchy feel for the kick down. They have 6 pins on the connector, I am not sure of the interal schmatics. It might be another option... the msrp on the pedal is $97 and the bracket it installs with $6. 10.



Just a thought.

 

[sbentz]

Nice thread!

OK, my 2 cents worth...



When I originally set up the 24v in the dragster with the VP44 pump, I used a seperate pedal assembly from a KW or Pete (manufacured by Williams) and hand wired it in. The 6 pin socket for the ISB is the same schematic as the HD engines.



If you want, you could try a pedal assembly, or a seperate TPS from one.



There is (as you all have found) 6 wires, all to support the idle validation switch. and the actual TPS circuit.



I have a few HD truck pedals around here somewhere.



We and the truck OEM's sell a seperate TPS/idle validation switch assembly as a replacent part. Maybe rig it in??



I looked for the spec for you, but am home and having issues logging into the secret world of Cummins corporate info...



I will see what I can find in the AM. .

 

[Sticks]

Thanks for your input Scott. Looks like we may have a cure for the $400 part after all.

 

[Blackbird]

Thanks for the input. Glad to see that we are thinking along the right lines...



One ???

What are the expected signals from the idle validation switches?

Is one close @ idle & other closed off idle or ?

Haven't had time to sit down w/ meter & old APPS to check. Dodge & Williams Controls pin out/schematics are confusing on this.



Jay