Truck cruise control problem

[Pittenger5]

So when I push the cruise control button on my truck, the "cruise" light goes on for like 10 seconds then shuts off. Even if I push the button again, it wont turn on at all, and of course cruise control itself doesnt work. Once I shut the truck off and turn it on again, I push the button and it lights up, then shuts off after 10 seconds again.
Any idea what could be causing this? Tried a diagnostic tool thing and nothing came up from it.

[SRTie4k]

Cruise control is generally controlled through the ECU. Odd that a CEL wouldn't pop up since it's pretty much 100% electronic these days.

Have you checked the owners manual? Maybe there are requirements for cruise (like not being in low or 4WD)? Just stabbing in the dark here.

[mycirus]

What kind of truck?

[Pittenger5]

02 Dodge Ram 1500

[mycirus]

Found this online.http://dodgeforum.com/forum/3rd-gen-...00-2002-a.html Post #4 has good info. Copied below.

When you turn the cruise control on the computer goes thru and checks conditions of certain things, Among which are brake lights, Speed sensor, Battery charge. If any of those items are not working properly the CC will shut itself off.

Check for codes. Sometimes you get lucky and it stores a code.
When you are driving is your Speedo Steady, Do you see any jumping or fluctuating in it?
First make sure ALL your brake lights (Including Light on the back CAB) are working. Also a mis-adjusted brake lamp switch can cause the cc to not work.
Make sure your battery is in good shape. If it's not the CC won't always work.
Listen at the resvoire and servo for anything obvious.
Check your throttle body linkage and air valve.


Also Here is the Alldata description of your CC, Hope some of this helps.
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Cruise Control: Description and Operation SPEED CONTROL The speed control system is electronically controlled and vacuum operated. Electronic control of the speed control system is integrated into the Powertrain Control Module (PCM). The controls consist of two steering wheel mounted switches. The switches are labeled: ON/OFF, RES/ACCEL, SET, COAST, and CANCEL.
The system is designed to operate at speeds above 30 mph (50 km/h).
WARNING: THE USE OF SPEED CONTROL IS NOT RECOMMENDED WHEN DRIVING CONDITIONS DO NOT PERMIT MAINTAINING A CONSTANT SPEED, SUCH AS IN HEAVY TRAFFIC OR ON ROADS THAT ARE WINDING, ICY, SNOW COVERED, OR SLIPPERY.
When speed control is selected by depressing the ON switch, the PCM allows a set speed to be stored in PCM RAM for speed control. To store a set speed, depress the SET switch while the vehicle is moving at a speed between 35 and 85 mph. In order for the speed control to engage, the brakes cannot be applied, nor can the gear selector be indicating the transmission is in Park or Neutral.
The speed control can be disengaged manually by:-Stepping on the brake pedal-Depressing the OFF switch-Depressing the CANCEL switch.-Depressing the clutch pedal (if equipped).
NOTE: Depressing the OFF switch or turning off the ignition switch will erase the set speed stored in the PCM.
For added safety the speed control system is programmed to disengage for any of the following conditions:-An indication of Park or Neutral-A rapid increase rpm (indicates that the clutch has been disengaged)-Excessive engine rpm (indicates that the transmission may be in a low gear)-The speed signal increases at a rate of 10 mph per second (indicates that the coefficient of friction between the road surface and tires is extremely low)-The speed signal decreases at a rate of 10 mph per second (indicates that the vehicle may have decelerated at an extremely high rate)
Once the speed control has been disengaged, depressing the RES/ACCEL switch (when speed is greater than 30 mph) restores the vehicle to the target speed that was stored in the PCM.
While the speed control is engaged, the driver can increase the vehicle speed by depressing the RES/ACCEL switch. The new target speed is stored in the PCM when the RES/ACCEL is released. The PCM also has a "tap-up" feature in which vehicle speed increases at a rate of approximately 2 mph for each momentary switch activation of the RES/ACCEL switch.
A "tap down" feature is used to decelerate without disengaging the speed control system. To decelerate from an existing recorded target speed, momentarily depress the COAST switch. For each switch activation, speed will be lowered approximately 1 mph.
Overshoot/Undershoot If the vehicle operator repeatedly presses and releases the SET button with their foot off of the accelerator (referred to as a "lift foot set"), the vehicle may accelerate and exceed the desired set speed by up to 5 mph (8 km/h). It may also decelerate to less than the desired set speed, before finally achieving the desired set speed.
The Speed Control System has an adaptive strategy that compensates for vehicle-to-vehicle variations in speed control cable lengths. When the speed control is set with the vehicle operators foot off of the accelerator pedal, the speed control thinks there is excessive speed control cable slack and adapts accordingly If the "lift foot sets" are continually used, a speed control overshoot/undershoot condition will develop.
To "unlearn" the overshoot/undershoot condition, the vehicle operator has to press and release the set button while maintaining the desired set speed using the accelerator pedal (not decelerating or accelerating), and then turning the cruise control switch to the OFF position (or press the CANCEL button if equipped) after waiting 10 seconds . This procedure must be performed approximately 10-15 times to completely unlearn the overshoot/undershoot condition.
CABLE The speed control servo cable is connected between the speed control vacuum servo diaphragm and the throttle body control linkage.
This cable causes the throttle control linkage to open or close the throttle valve in response to movement of the vacuum servo diaphragm.
SERVO The speed control servo is attached to the bottom of the battery tray.
The servo unit consists of a solenoid valve body, and a vacuum chamber. The solenoid valve body contains three solenoids:
-Vacuum-Vent-Dump
The vacuum chamber contains a diaphragm with a cable attached to control the throttle linkage.
The Powertrain Control Module (PCM) controls the solenoid valve body. The solenoid valve body controls the application and release of vacuum to the diaphragm of the vacuum servo. The servo unit cannot be repaired and is serviced only as a complete assembly.
Power is supplied to the servo's by the PCM through the brake switch. The PCM controls the ground path for the vacuum and vent solenoids.
The dump solenoid is energized anytime it receives power. If power to the dump solenoid is interrupted, the solenoid dumps vacuum in the servo. This provides a safety backup to the vent and vacuum solenoids.
The vacuum and vent solenoids must be grounded at the PCM to operate. When the PCM grounds the vacuum servo solenoid, the solenoid allows vacuum to enter the servo and pull open the throttle plate using the cable. When the PCM breaks the ground, the solenoid closes and no more vacuum is allowed to enter the servo. The PCM also operates the vent solenoid via ground. The vent solenoid opens and closes a passage to bleed or hold vacuum in the servo as required.
The PCM duty cycles the vacuum and vent solenoids to maintain the set speed, or to accelerate and decelerate the vehicle. To increase throttle opening, the PCM grounds the vacuum and vent solenoids. To decrease throttle opening, the PCM removes the grounds from the vacuum and vent solenoids. When the brake is released, if vehicle speed exceeds 30 mph to resume, 35 mph to set, and the RES/ACCEL switch has been depressed, ground for the vent and vacuum circuits is restored.
SWITCH There are two separate switch pods that operate the speed control system. The steering-wheel-mounted switches use multiplexed circuits to provide inputs to the PCM for ON, OFF, RESUME, ACCELERATE, SET, DECEL and CANCEL modes. Refer to the owner's manual for more information on speed control switch functions and setting procedures.
The individual switches cannot be repaired. If one switch fails, the entire switch module must be replaced.
When speed control is selected by depressing the ON, OFF switch, the PCM allows a set speed to be stored in its RAM for speed control. To store a set speed, depress the SET switch while the vehicle is moving at a speed between approximately 35 and 85 mph. In order for the speed control to engage, the brakes cannot be applied, nor can the gear selector be indicating the transmission is in Park or Neutral.
The speed control can be disengaged manually by:-Stepping on the brake pedal-Depressing the OFF switch-Depressing the CANCEL switch.
The speed control can be disengaged also by any of the following conditions:-An indication of Park or Neutral-The VSS signal increases at a rate of 10 mph per second (indicates that the co-efficient of friction between the road surface and tires is extremely low)-Depressing the clutch pedal.-Excessive engine rpm (indicates that the transmission may be in a low gear)-The VSS signal decreases at a rate of 10 mph per second (indicates that the vehicle may have decelerated at an extremely high rate)-If the actual speed is not within 20 mph of the set speed
The previous disengagement conditions are programmed for added safety. Once the speed control has been disengaged, depressing the ACCEL switch restores the vehicle to the target speed that was stored in the PCM's RAM.
NOTE: Depressing the OFF switch will erase the set speed stored in the PCM's RAM.
If, while the speed control is engaged, the driver wishes to increase vehicle speed, the PCM is programmed for an acceleration feature. With the ACCEL switch held closed, the vehicle accelerates slowly to the desired speed. The new target speed is stored in the PCM's RAM when the ACCEL switch is released. The PCM also has a "tap-up" feature in which vehicle speed increases at a rate of approximately 2 mph for each momentary switch activation of the ACCEL switch.
The PCM also provides a means to decelerate with- out disengaging speed control. To decelerate from an existing recorded target speed, depress and hold the COAST switch until the desired speed is reached. Then release the switch. The ON, OFF switch operates two components: the PCM's ON, OFF input, and the battery voltage to the brake switch, which powers the speed control servo.
Multiplexing The PCM sends out 5 volts through a fixed resistor and monitors the voltage change between the fixed resistor and the switches. If none of the switches are depressed, the PCM will measure 5 volts at the sensor point (open circuit). If a switch with no resistor is closed, the PCM will
measure 0 volts (grounded circuit). Now, if a resistor is added to a switch, then the PCM will measure some voltage proportional to the size of the resistor. By adding a different resistor to each switch, the PCM will see a different voltage depending on which switch is pushed.
Another resistor has been added to the 'at rest circuit' causing the PCM to never see 5 volts. This was done for diagnostic purposes. If the switch circuit should open (bad connection), then the PCM will see the 5 volts and know the circuit is bad. The PCM will then set an open circuit fault.
VACUUM RESERVOIR The vacuum reservoir is a plastic storage tank connected to an engine vacuum source by vacuum lines.
The vacuum reservoir is used to supply the vacuum needed to maintain proper speed control operation when engine vacuum drops, such as in climbing a grade while driving. A one-way check valve is used in the vacuum line between the reservoir and the vacuum source. This check valve is used to trap engine vacuum in the reservoir. On certain vehicle applications, this reservoir is shared with the heating/air-conditioning system. The vacuum reservoir cannot be repaired and must be replaced if faulty.

[pk4882]

Did you put LED bulbs in your tail / brake lights?

I did on my Pathfinder... 4 months later, my cruise control started doing the exact same thing. Regular bulbs back in, problem solved.

PK