NO THROTTLE RESPONSE - FIXED!! Diesel pusher

[BigPapaYams]

That may sound like a weird title - let me explain. A bit long but thorough.

In a "gasser" or most conventional front-engined vehicles, there is a cable that reaches between the throttle pedal and the engine. Push the pedal, the cable attached to the engine moves, causing acceleration (or deceleration). Some cars now use "throttle by wire" systems but it isn't all that common yet.

Pushers (as you know) have the engine in the rear but the driver controls the vehicle from the front. Having a cable (mechanical link) from the throttle pedal to the engine 30-40 behind the driver isn't ideal. My coach, a 1996 Monaco Dynasty (Roadmaster Chassis, Cummins 8.3 and Allison 3060 automatic transmission, King Controls K-2600 throttle / cruise control system) had a "throttle by wire" system. Instead of a cable between the throttle and injection pump, an electronic signal is transferred by wire (hence, "throttle by wire"). The throttle pedal creates a signal that is sent by wire to a control box in the engine compartment that in turn will pull (or push) on a cable attached to the injection pump (usually to an arm). Push the throttle a little, the control box pulls the cable a little, engine accelerates slowly. Mash the throttle, pedal sends a different signal, control box pulls the cable a lot and you get full power / acceleration. Simple and elegant.

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!!

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.

[MSHappyCampers]

Jay, I can see you're gonna be a handy guy to have around here!

[GraySeal65]

Steve is a great guy, he did my King box last year. He has real good diagnosis information on his site to.
Semi Truck, Bus, RV, Service Vehicle Cruise Control Installation
http://www.cruisecontrolking.com/#throttle

[windsorbill]

Great story. I like your temp fix with the cord.

[TonyDi]

Thanks for that write-up. I am having a similar problem. It happens so seldom that it's hard to diagnose. Now I know what to have my mechanic look into.

[dons2346]

Have a friend that drove a Country Coach back from the east coast using the "MacGyver" method during the snow season. He said it wasn't fun.

I find it interesting about the box having lights in it.Do you have an idea as to what they did or what they signaled?

Good work

[mojoracing]

I want to see what you do when the paracord catches on something! Now that would be good video! Just kidding, great job on the diagnosis and finding a fix! A man after my own heart.

[UncleBilly]

Thanks for sharing. I will keep this thread and hope I never have too use this info 😜👍🏻👍🏻


1996 Country Coach Intrigue 😜

[joeplazek]

It’s amazing what we can up with while stranded on the road. Great job!

[twinboat]

You folks with Ford MHs, if you get the same symptoms, it's because Ford has been using Throttle By Wire since around 2000.

[Bart Anderson]

Originally Posted by BigPapaYams

That may sound like a weird title - let me explain. A bit long but thorough.

In a "gasser" or most conventional front-engined vehicles, there is a cable that reaches between the throttle pedal and the engine. Push the pedal, the cable attached to the engine moves, causing acceleration (or deceleration). Some cars now use "throttle by wire" systems but it isn't all that common yet.

Pushers (as you know) have the engine in the rear but the driver controls the vehicle from the front. Having a cable (mechanical link) from the throttle pedal to the engine 30-40 behind the driver isn't ideal. My coach, a 1996 Monaco Dynasty (Roadmaster Chassis, Cummins 8.3 and Allison 3060 automatic transmission, King Controls K-2600 throttle / cruise control system) had a "throttle by wire" system. Instead of a cable between the throttle and injection pump, an electronic signal is transferred by wire (hence, "throttle by wire"). The throttle pedal creates a signal that is sent by wire to a control box in the engine compartment that in turn will pull (or push) on a cable attached to the injection pump (usually to an arm). Push the throttle a little, the control box pulls the cable a little, engine accelerates slowly. Mash the throttle, pedal sends a different signal, control box pulls the cable a lot and you get full power / acceleration. Simple and elegant.

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!!

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.

I remember in Vietnam having to travel out to the jungle to work on an H34 reciprocal engine Helicopter with a broken throttle cable. When I got there the VNAF pilot said “ we fix..we go now” I looked at his “repair” he had shot a hole down from the cockpit with his M16 and run a string from the throttle body back up into the cockpit and tied it around the co-pilot’s finger!
Needless to say, I refused to get on board that death trap and watched (from a safe distance) them take off with that crazy rig!
Unbelievable to me, they actually flew it thirty miles back to Ban Me Thuot and land safely while I spent hours in the NVA infested jungle waiting on a helo ride home!
Anything is possible to do I guess if you need to badly enough!

[hohenwald48]

I've noticed on my Nissan Armada (gas) that the throttle by wire does not respond if I have the brake pedal depressed. Just thought I'd throw out that bit of info for no particular reason.

[megehrs]

Great MacGyver work. Thanks for sharing

[guardrail53]

My 96 Monaco Windsor does this "Limp Throttle" at times too, mostly when I first start it up, no throttle response for a min. or so! Then it works as it should! I have not noticed it while driving, but gotten used to it when I first start it! I will now know what to do, and how to repair it in the future! Thanks for a great write up, Jay!

My thoughts on the paracord throttle, what happens if the dog trips on it, or, god forbid, decides on a tug of war game! Now that would be a ride! Rail!