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KC 2600 Throttle System Diagnostic Chart

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NO THROTTLE, NO CRUISE, NO FAST IDLE

 

SYMPTOM: TRANSMISSION TPS PROBLEMS: WON’T SHIFT INTO GEAR, WILL NOT SHIFT FROM LOWER TO HIGHER GEARS, HARSH SHIFTING

2 SYMPTOM- TRANSMISSION TPS PROBLEMS- WON’T SHIFT INTO GEAR.png

 

3 SYMPTOM- STEPPING ON FOOT PEDAL ONLY GIVES PARTIAL THROTTLE.png

 

4 CRUISE WILL NOT SET AND DOES NOT ACTIVATE IN IDLE MODE

 

5 CRUISE SETS, BUT WILL NOT RESUME

 

6 SYMPTOM- IDLE MODE WILL NOT SET OR HOLD, CRUISE WORKS FINE

 

7 SYMPTOM- THROTTLE STICKS OFF IDLE

 

8 SYMPTOM- CRUISE SURGES OR BOOST FLUCTUATES OR OVER ACCELERATES WHEN IN CRUISE MODE

 

9 SYMPTOM- CRUISE WORKS IN IDLE MODE BUT WILL NOT SET GOING DOWN ROAD

 

KC2600 Foot Throttle Wiring DiagramKC2600 Foot Throttle Wiring Diagram

 

King Control (cruise control and throttle control) circuit board has a connection to the rear brake light circuit for two purposes.   

1) If cruise control is active and the brake light come on, cruise control turns off, only to come back on with a new "set" or "resume".   
2) If the throttle control circuit does not see a ground connection through  a brake light bulb, the coach will only accelerate to about 10 mph no matter how hard the throttle pedal is pressed. Burned out brake light bulbs will cause this situation. And a missing wire connection to brake lights will also cause this problem. King wants to know it can sense brake lights, so it can turn cruise off when brake lights will come on. If King does not see ground, it assumes brake light wire is missing.  

Pressing the air brake pedal puts air pressure to brake switches, turning on brake lights.  

When the transmission retarder joy stick is added, a relay is added just to turn on Foretravel brake lights. Allison does not require this relay to activate the retarder from the joy stick.  

When the retarder is activated by using the brake pedal, brake lights turn on from air pressure switches.  

If someone adds a joy stick and does not add the relay, joy stick retard will not turn on brake lights. And if driving on a highway with cruise control on and joy stick in a retard position, and the coach goes down a dip, the accelerator goes to zero position, retard comes on, and when the coach reaches the bottom of the dip, the coach will again accelerate and retard will go off.  

If the relay is in place because the joy stick was originally part of the coach or the relay added, every retard action will turn on brake lights and immediately turn off cruise, which stays off and must be reactivated manually.  

One can have a dash switch on the new relay control wire to choose between having brake lights come on with joy stick retard, or not come on.

Here is the Foretravel wiring diagram for the add-on retarder relay located near the brake light air switches.  When this relay is closed, it turns on the brake lights.  

This add-on relay is triggered by the retarder relay on the main circuit breaker panel by the front door.

 

Retarder Relay

Barry and Cindy 1997 U270 36' 

King Control diagram

 

The Bosch relay mounted beside and outboard of the two Brake Light switches on the forward bulkhead is the added relay that Barry Levitt speaks of.

brake light switch

brake light switch

Photos by Peter & Beth Martin 1997 U270 34'

Pull that relay and check for high resistance/clean and lube? I've found "not-ideal, resistance (10's to 100's of ohms of resistance), should be a dead short when relay is energized". I've replaced mine twice.  
It is not a friendly home for this component and therefore need to pamper a bit.  

FWIW,  Neal Pillsbury 1998 U270 36'

On my '96 U295 the control is an aluminum box under the bed in the forward, passenger side corner in the engine room. Made by King Controls. Elliott Bray 1996 U295 36'

On my 95 the cruise is Bendix,  I have separate cruise and air throttle.  If cruise quits I still have throttle.  On some if King Control quits you have no throttle. Gary B

© Barry Brideau 2003-2016