Erratic Performance & System Diagnosis

ERRATIC PERFORMANCE CAN USUALLY BE TRACED TO THE FOLLOWING CONDITIONS:

COMPLAINT: "Does not hold speed, cruises below set speed or drops when set and then returns."

Causes: a. Bead chain or throttle cable has too much slack
b. Sluggish operation of vacuum valve
c. Speedometer cable whip
d. Wires from sensor touching high voltage wires

COMPLAINT: "Does not hold speed, cruises above set speed."
Causes: a. Sluggish vent valve

COMPLAINT: "Sets, disengages, but will resume."
Causes: a. Speedometer cable whip
b. Sensor wire routed past high voltage lead
c. Loose connection at brake or clutch switch or improper adjustment

COMPLAINT: "Sets, disengages, and will not resume."
Causes: a. Loose connection on + 12V feed wire to module
b. Circuit feeding + 12V to cruise does not remain on all the time
c. Bad control switch

COMPLAINT: "No resume."
Causes: a. Bad control switch or associated wiring
b. Bad module

COMPLAINT: "Speed increases from set speed."
Causes: a. Stuck valve
b. Short in valve wiring (ground from vent or vacuum valve)

COMPLAINT: "Gradually loses speed."

Causes: a. Poor vacuum source (pinched or leaky hose)
b. Leaky reservoir or actuator assembly
c. Prolonged periods of full throttle use. Normal, no repair
d. Leaking valve body

COMPLAINT: "Surges, jerks, wanders around set speed."
Causes: a. Vacuum source not constant
b. Throttle cable binding
c. Excess slack in throttle cable or bead chain
d. Speedometer cable whip
e. Sluggish valves

COMPLAINT: "No accel."
Causes: a. Faulty control switch or associated wiring
b. Faulty module
c. Excessive speedometer cable whip

COMPLAINT: "No coast."
Causes: a. Faulty control switch or associated wiring
b. Faulty module









SPEED CONTROL SYSTEM DIAGNOSIS