Throttle Position Sensor Fault (TPS)

[barmcd]

Here's the procedure.

Turn the key to the first position, power on, but DO NOT start the engine. You don't have to wait for the gauges to cycle, etc.

Slowly, but steadily, push the accelerator pedal to the full acceleration position, then release it with the same slow, steady motion. Do not let off it abruptly.

Repeat this procedure TWO more times.

Then, turn the key to the OFF position. Leave the key off for a MINIMUM of 30 seconds. Longer is okay, shorter is not.

The engine ECM recognizes this as a calibration procedure.

[MSGulfCoast]

Thank you. Sure hope this works!

[barmcd]

Good luck

[MSGulfCoast]

Well either I didn't do it correctly or this doesn't work for my Dynasty!
There was no response to the pedal being depressed. Back to the drawing board!

[Dthomas0621]

I had the same problem. The wiring diagram from the coach and chassis manufacturers are WRONG. Get the correct wiring diagram from the TPS manufacturer. I went through 3 ECMs and several other electrical problems because of this. It’s so nice to able to stop at traffic signals and not worry about having to shut the engine down and restart it just to get through an intersection.
Good luck.

[MSGulfCoast]

Oh my! Didn't think about that being a problem.

[Jeff753]

Like to revive this post. My 2001 350 ISC did this today on the way home from the Tampa show. Warning light came on as I let off for a turn. I turned the corner and it just would idle. I noticed my vmspc showed the throttle at 0 even though I pushed it.
It started working again after a few presses and minutes. Drove the last 40 miles. What is the part and is the calibration procedure as described above?

[Damion]

These are a couple post I've saved off here for future reference!
Good Luck!


Turn the key to the first position, power on, but DO NOT start the engine. You don't have to wait for the gauges to cycle, etc.

Slowly, but steadily, push the accelerator pedal to the full acceleration position, then release it with the same slow, steady motion. Do not let off it abruptly.

Repeat this procedure TWO more times.

Then, turn the key to the OFF position. Leave the key off for a MINIMUM of 30 seconds. Longer is okay, shorter is not.

The engine ECM recognizes this as a calibration procedure.


Semi Truck, Bus, RV, Service Vehicle Cruise Control Installation
Semi Truck, Bus, RV, Service Vehicle Cruise Control Installation
WHERE I HAD A PROBLEM
In 2016, I noticed a problem while driving where once in a while, the throttle pedal seemed to be "dead". I would push on the throttle pedal and there was no corresponding reaction from the engine. Usually a very short time, a second or two and while under way, not a big deal. Things get a little uncomfortable when at a stop light / sign and the pedal doesn't react...

Over the course of about 8 months, things got a little worse. On our last trip in October 2016, we actually had to pull over and come to a stop a few times before I got throttle back. Finally, on our way home (about 125 miles out) the throttle quit altogether.

I chose to take a "MacGyver" approach where I lifted the bed, tied a 50-ft length of paracord to the arm on the fuel injection pump and ran it to the driver seat where I pulled it "by hand" to control the throttle. Not fun but we got home. I ADMIT - not ideal, diminished safety etc. I just wanted to get home.

DIAGNOSIS
I am a fairly accomplished shade-tree mechanic / DIYer so I was determined to figure this out. Besides, I don't MAKE $150-hour so I hate to pay that to someone for something I might accomplish on my own.

Mulled it over for a few weekends, decided to start at the front and work back. Removed the throttle pedal from the firewall, ran some electrical tests on it and it checked out fine. I attempted to run some tests on the wires between the pedal and the "controller box" but couldn't seem to get it right. I thought I might have to trace the wires from front to back to find a break etc.

Finally, with my wife helping out, I kneeled down next to the flipped up bed / engine compartment to observe what was happening and/or what I might hear. She turned the key to on (not so far as to crank the engine over) and then I asked her to slowly depress the throttle pedal. I heard some noise but the cable between the controller box and the injection pump arm did NOT move. AHA!! Now we're getting somewhere.

I removed the six screws from the top of the box and noted a circuit board with some lights etc. I asked her to again depress the throttle slowly and then let off the throttle slowly. I saw a small motor rotating (in a jerky manner) first when she depressed the pedal and the opposite direction when she let the pedal come back up. NO MOVEMENT OF THE CABLE TO THE INJECTION PUMP!! PROBLEM DIAGNOSED!!

NOW WHAT?!?
After a little bit of searching on the WWW, I contacted Steve at CRUISE KING, LLC (Semi Truck, Bus, RV, Service Vehicle Cruise Control Installation or (507) 334-0250). I gave him the run-down on the symptoms and what I had discovered. Parts are not available but he does a complete rebuild of the control box and all components for $475.00 with ONE DAY TURN-AROUND time!! [IMG]file:///C:\Users\Dave\AppData\Local\Temp\msohtmlclip1\01\c lip_image001.gif[/IMG]

I shipped off my box (cost me ~$20 via UPS) and Steve called me the day after UPS delivered it. He said it was already done and he needed my Credit card info so he could charge me and ship it back. SWEET!!

ON THE ROAD AGAIN!!
I installed the rebuilt controller box this past weekend. Plugged the wires in, connected the cable to the arm on the fuel injection pump and did the visual test of "does the cable move / pull on the injection pump arm when the throttle is depressed?" YES IT DOES!! Turn the key, fire the engine up and push the throttle - WE HAVE THROTTLE response.

"The Bus" drives again without the help / hindrance of a 50-ft. length of paracord.

[Dthomas0621]

It only cost me $10,000 to solve. Monaco’s and Cummins wiring diagrams are WRONG. Contact the TPS manufacturer, Williams, for the correct diagram.

[Jeff753]

Originally Posted by Damion

These are a couple post I've saved off here for future reference!
Good Luck!


Turn the key to the first position, power on, but DO NOT start the engine. You don't have to wait for the gauges to cycle, etc.

Slowly, but steadily, push the accelerator pedal to the full acceleration position, then release it with the same slow, steady motion. Do not let off it abruptly.

Repeat this procedure TWO more times.

Then, turn the key to the OFF position. Leave the key off for a MINIMUM of 30 seconds. Longer is okay, shorter is not.

The engine ECM recognizes this as a calibration procedure.


Semi Truck, Bus, RV, Service Vehicle Cruise Control Installation
Semi Truck, Bus, RV, Service Vehicle Cruise Control Installation
WHERE I HAD A PROBLEM
In 2016, I noticed a problem while driving where once in a while, the throttle pedal seemed to be "dead". I would push on the throttle pedal and there was no corresponding reaction from the engine. Usually a very short time, a second or two and while under way, not a big deal. Things get a little uncomfortable when at a stop light / sign and the pedal doesn't react...

Over the course of about 8 months, things got a little worse. On our last trip in October 2016, we actually had to pull over and come to a stop a few times before I got throttle back. Finally, on our way home (about 125 miles out) the throttle quit altogether.

I chose to take a "MacGyver" approach where I lifted the bed, tied a 50-ft length of paracord to the arm on the fuel injection pump and ran it to the driver seat where I pulled it "by hand" to control the throttle. Not fun but we got home. I ADMIT - not ideal, diminished safety etc. I just wanted to get home.

DIAGNOSIS
I am a fairly accomplished shade-tree mechanic / DIYer so I was determined to figure this out. Besides, I don't MAKE $150-hour so I hate to pay that to someone for something I might accomplish on my own.

Mulled it over for a few weekends, decided to start at the front and work back. Removed the throttle pedal from the firewall, ran some electrical tests on it and it checked out fine. I attempted to run some tests on the wires between the pedal and the "controller box" but couldn't seem to get it right. I thought I might have to trace the wires from front to back to find a break etc.

Finally, with my wife helping out, I kneeled down next to the flipped up bed / engine compartment to observe what was happening and/or what I might hear. She turned the key to on (not so far as to crank the engine over) and then I asked her to slowly depress the throttle pedal. I heard some noise but the cable between the controller box and the injection pump arm did NOT move. AHA!! Now we're getting somewhere.

I removed the six screws from the top of the box and noted a circuit board with some lights etc. I asked her to again depress the throttle slowly and then let off the throttle slowly. I saw a small motor rotating (in a jerky manner) first when she depressed the pedal and the opposite direction when she let the pedal come back up. NO MOVEMENT OF THE CABLE TO THE INJECTION PUMP!! PROBLEM DIAGNOSED!!

NOW WHAT?!?
After a little bit of searching on the WWW, I contacted Steve at CRUISE KING, LLC (Semi Truck, Bus, RV, Service Vehicle Cruise Control Installation or (507) 334-0250). I gave him the run-down on the symptoms and what I had discovered. Parts are not available but he does a complete rebuild of the control box and all components for $475.00 with ONE DAY TURN-AROUND time!! [IMG]file:///C:\Users\Dave\AppData\Local\Temp\msohtmlclip1\01\c lip_image001.gif[/IMG]

I shipped off my box (cost me ~$20 via UPS) and Steve called me the day after UPS delivered it. He said it was already done and he needed my Credit card info so he could charge me and ship it back. SWEET!!

ON THE ROAD AGAIN!!
I installed the rebuilt controller box this past weekend. Plugged the wires in, connected the cable to the arm on the fuel injection pump and did the visual test of "does the cable move / pull on the injection pump arm when the throttle is depressed?" YES IT DOES!! Turn the key, fire the engine up and push the throttle - WE HAVE THROTTLE response.

"The Bus" drives again without the help / hindrance of a 50-ft. length of paracord.

Great thread here. Love the paracord solution. What motor do you have? I have the 350 ISC.
Do you have a picture of the box you sent in? If you replace the TPS...On calibration do you cycle the key each time you push the pedal.
Pretty odd to push the throttle with no response. Luckily I have the silver leaf vmspc and noticed 0% throttle deflection. Here’s my error code again.

[Jeff753]

I have some spray for potentiometers made by Deoxit. If I take these two screws out will this tps be hard to get back on? I don’t know if there is a spring back there or what. I don’t want to be towed

[barmcd]

Originally Posted by Jeff753

Like to revive this post. My 2001 350 ISC did this today on the way home from the Tampa show. Warning light came on as I let off for a turn. I turned the corner and it just would idle. I noticed my vmspc showed the throttle at 0 even though I pushed it.
It started working again after a few presses and minutes. Drove the last 40 miles. What is the part and is the calibration procedure as described above?
Attachment 232604

It's your TPS. You have an electronic engine so it's a simple fix. Two screws and a connector. Do you need the p/n?

[Jeff753]

Originally Posted by barmcd

It's your TPS. You have an electronic engine so it's a simple fix. Two screws and a connector. Do you need the p/n?

Part number would be great. So the ISC is an electronic engine meaning?
I heard there is a control box that opens the injector pump? Is that true with an electronic engine?

[barmcd]

Originally Posted by Jeff753

Part number would be great. So the ISC is an electronic engine meaning?
I heard there is a control box that opens the injector pump? Is that true with an electronic engine?

The ISC engine has an ECM which controls pretty much everything. The previous version of the 8.3 Cummins is called a mechanical engine because it doesn't have electronics controlling the engine functions. I believe the control box you are referencing is the King unit which was supplied on some mechanical engines. I'm not real familiar with them, but I know how the ISC works.

Here's a link to the TPS for an ISC.



https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1