Cruise Control stopped working?
12-27-2006, 09:08 AM
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Cruise Control stopped working?
Ok, my cruise control has stopped working correctly. When I set it on they hwy, it will set for about 15 sec or until I hit a grade in the road and the motor has to work harder. Then it cuts off and wont come back on at all until I recycle the keys. What is up with this? Is it some sort of controller that went out, or is it as simple as a bad fuse?
12-05-2007, 08:39 AM
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12-05-2007, 08:51 AM
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5.9L Diesel
The speed control system is fully electronically controlled by the Powertrain Control Module (PCM). If equipped with
a diesel engine, electronic control of the speed control system is integrated into the Engine Control Module (ECM).
A cable and a vacuum controlled servo are not used. This is a servo-less system. The controls consist of two
steering wheel mounted switches. The switches are labeled: ON/OFF, RES/ACCEL, SET, COAST, and CANCEL
DIAGNOSIS AND TESTING - ROAD TEST
Perform a vehicle road test to verify reports of speed control system malfunction. The road test should include attention
to the speedometer. Speedometer operation should be smooth and without flutter at all speeds.
Flutter in the speedometer indicates a problem which might cause surging in the speed control system. The cause
of any speedometer problems should be corrected before proceeding. Refer to Instrument Cluster for speedometer
diagnosis.
If a road test verifies a system problem and the speedometer operates properly, check for:
² A Diagnostic Trouble Code (DTC). If a DTC exists, conduct tests per the Powertrain Diagnostic Procedures
service manual.
² A misadjusted brake (stop) lamp switch. This could also cause an intermittent problem.
² Loose, damaged or corroded electrical connections at the servo (if used). Corrosion should be removed from
electrical terminals and a light coating of Mopar T MultiPurpose Grease, or equivalent, applied.
² Leaking vacuum reservoir (if used).
² Loose or leaking vacuum hoses or connections (if used).
² Defective one-way vacuum check valve (if used).
² Secure attachment of both ends of the speed control servo cable (if used).
DR SPEED CONTROL 8P - 3
² Smooth operation of throttle linkage (if used) and throttle body air valve.
² Failed speed control servo (if used). Do the servo vacuum test.
CAUTION: When test probing for voltage or continuity at electrical connectors, care must be taken not to
damage connector, terminals or seals. If these components are damaged, intermittent or complete system failure may occur
A speed control servo cable is not used if equipped with either a 5.9L diesel engine, or any 5.7L engine
The speed control system is fully electronically controlled by the Powertrain Control Module (PCM). If equipped with
a diesel engine, electronic control of the speed control system is integrated into the Engine Control Module (ECM).
A cable and a vacuum controlled servo are not used. This is a servo-less system. The controls consist of two
steering wheel mounted switches. The switches are labeled: ON/OFF, RES/ACCEL, SET, COAST, and CANCEL
DIAGNOSIS AND TESTING - ROAD TEST
Perform a vehicle road test to verify reports of speed control system malfunction. The road test should include attention
to the speedometer. Speedometer operation should be smooth and without flutter at all speeds.
Flutter in the speedometer indicates a problem which might cause surging in the speed control system. The cause
of any speedometer problems should be corrected before proceeding. Refer to Instrument Cluster for speedometer
diagnosis.
If a road test verifies a system problem and the speedometer operates properly, check for:
² A Diagnostic Trouble Code (DTC). If a DTC exists, conduct tests per the Powertrain Diagnostic Procedures
service manual.
² A misadjusted brake (stop) lamp switch. This could also cause an intermittent problem.
² Loose, damaged or corroded electrical connections at the servo (if used). Corrosion should be removed from
electrical terminals and a light coating of Mopar T MultiPurpose Grease, or equivalent, applied.
² Leaking vacuum reservoir (if used).
² Loose or leaking vacuum hoses or connections (if used).
² Defective one-way vacuum check valve (if used).
² Secure attachment of both ends of the speed control servo cable (if used).
DR SPEED CONTROL 8P - 3
² Smooth operation of throttle linkage (if used) and throttle body air valve.
² Failed speed control servo (if used). Do the servo vacuum test.
CAUTION: When test probing for voltage or continuity at electrical connectors, care must be taken not to
damage connector, terminals or seals. If these components are damaged, intermittent or complete system failure may occur
A speed control servo cable is not used if equipped with either a 5.9L diesel engine, or any 5.7L engine
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12-05-2007, 04:31 PM
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Mine is an early 04.
..so its probably a problem with the ECM? Would clearing any codes with say my Smarty help??
That is too much for me to handle^
..so its probably a problem with the ECM? Would clearing any codes with say my Smarty help??
That is too much for me to handle^
12-05-2007, 09:20 PM
#9
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Uhh, Well what the heck does the vaccum pump do? I have got one and never really looked at it. If it is vaccum controlled then you should have a dashpot. I have never paid any attention to it.
12-05-2007, 10:08 PM
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Ok, my cruise control has stopped working correctly. When I set it on they hwy, it will set for about 15 sec or until I hit a grade in the road and the motor has to work harder. Then it cuts off and wont come back on at all until I recycle the keys. What is up with this? Is it some sort of controller that went out, or is it as simple as a bad fuse?
12-06-2007, 12:41 PM
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SERVO
DESCRIPTION
A speed control servo is not used with any 5.7L V-8 engine, or with the 5.9L diesel engine.
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:
² Vacuum
² Vent
² Dump
The vacuum chamber contains a diaphragm with a cable attached to control the throttle linkage.
OPERATION
A speed control servo is not used with any 5.7L V-8 engine, or with the 5.9L diesel engine.
The following information applies only to vehicles equipped with a mechanical servo.
When/if a servo is used on gasoline powered vehicles, 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 (48.2kph) to resume, 35 mph (56.3 kph) to set, and the RES/ACCEL switch has been
depressed, ground for the vent and vacuum circuits is restored.
DR SPEED CONTROL 8P - 7
REMOVAL
The speed control servo assembly is attached to the
bottom of the battery tray (1).
1. Disconnect negative battery cable at battery (both
cables at both batteries if diesel).
2. To gain access to servo, remove plastic wheelhouse
splash shield over left-front wheel.
3. Disconnect vacuum line (7) at servo.
4. Disconnect electrical connector (4) at servo.
5. Remove 3 servo mounting screws (5). Depending
on engine application, different sets of mounting
lugs (2) are used to support servo to battery tray.
While removing, note proper lugs.
6. Disconnect servo cable at throttle body. Refer to
Servo Cable Removal/Installation.
7. Remove 2 mounting nuts (1) holding servo cable
sleeve to bracket.
8. Pull speed control cable sleeve and servo away
from servo mounting bracket to expose cable
retaining clip (3) and remove clip. Note: The servo
mounting bracket displayed is a typical bracket and
may/may not be applicable to this model vehicle.
9. Remove servo (2) from mounting bracket. While
removing, note orientation of servo to bracket.
INSTALLATION
1. Position servo to mounting bracket.
2. Align hole in cable connector with hole in servo pin. Install cable-to-servo retaining clip.
3. Insert servo mounting studs through holes in servo mounting bracket.
4. Install 2 servo-to-mounting bracket nuts and tighten to 60 in. lbs. (7 N·m).
5. Position servo assembly to correct mounting lugs on battery tray and install 3 screws. Tighten to 30 in. lbs. (4
N·m).
6. Connect vacuum line at servo.
7. Connect electrical connector at servo.
8. Connect servo cable to throttle body. Refer to servo Cable Removal/Installation.
9. Install left-front wheel-well liner.
10. Connect negative battery cable to battery (connect both cables if diesel).
11. Before starting engine, operate accelerator pedal to check for any binding.
DESCRIPTION
A speed control servo is not used with any 5.7L V-8 engine, or with the 5.9L diesel engine.
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:
² Vacuum
² Vent
² Dump
The vacuum chamber contains a diaphragm with a cable attached to control the throttle linkage.
OPERATION
A speed control servo is not used with any 5.7L V-8 engine, or with the 5.9L diesel engine.
The following information applies only to vehicles equipped with a mechanical servo.
When/if a servo is used on gasoline powered vehicles, 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 (48.2kph) to resume, 35 mph (56.3 kph) to set, and the RES/ACCEL switch has been
depressed, ground for the vent and vacuum circuits is restored.
DR SPEED CONTROL 8P - 7
REMOVAL
The speed control servo assembly is attached to the
bottom of the battery tray (1).
1. Disconnect negative battery cable at battery (both
cables at both batteries if diesel).
2. To gain access to servo, remove plastic wheelhouse
splash shield over left-front wheel.
3. Disconnect vacuum line (7) at servo.
4. Disconnect electrical connector (4) at servo.
5. Remove 3 servo mounting screws (5). Depending
on engine application, different sets of mounting
lugs (2) are used to support servo to battery tray.
While removing, note proper lugs.
6. Disconnect servo cable at throttle body. Refer to
Servo Cable Removal/Installation.
7. Remove 2 mounting nuts (1) holding servo cable
sleeve to bracket.
8. Pull speed control cable sleeve and servo away
from servo mounting bracket to expose cable
retaining clip (3) and remove clip. Note: The servo
mounting bracket displayed is a typical bracket and
may/may not be applicable to this model vehicle.
9. Remove servo (2) from mounting bracket. While
removing, note orientation of servo to bracket.
INSTALLATION
1. Position servo to mounting bracket.
2. Align hole in cable connector with hole in servo pin. Install cable-to-servo retaining clip.
3. Insert servo mounting studs through holes in servo mounting bracket.
4. Install 2 servo-to-mounting bracket nuts and tighten to 60 in. lbs. (7 N·m).
5. Position servo assembly to correct mounting lugs on battery tray and install 3 screws. Tighten to 30 in. lbs. (4
N·m).
6. Connect vacuum line at servo.
7. Connect electrical connector at servo.
8. Connect servo cable to throttle body. Refer to servo Cable Removal/Installation.
9. Install left-front wheel-well liner.
10. Connect negative battery cable to battery (connect both cables if diesel).
11. Before starting engine, operate accelerator pedal to check for any binding.
12-06-2007, 12:42 PM
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SWITCH
DESCRIPTION
Two separate switch pods operate the speed control system. The steering-wheel-mounted switches use multiplexed
circuits to provide inputs to the PCM (to the ECM for diesel) 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.
Depending on engine control computer (JTEC having a 3– plug connector or NGC having a 4– plug connector),
2 types of switches are used. Both types of switches are internally and externally different. The
switch used with the NGC system has an attached pigtail lead. The switch used with the JTEC system does
not have an attached pigtail lead.
OPERATION
When speed control is selected by depressing the ON, OFF switch, the PCM (ECM for diesel) 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 (56.2kph) and 85 mph (136.8kph). 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:
² Stepping on the brake pedal
² Depressing the OFF switch
² Depressing the CANCEL switch.
The speed control can be disengaged also by any of the following conditions:
² An indication of Park or Neutral (auto. trans.)
² The VSS signal increases at a rate of 10 mph (16 kph) per second (indicates that the co-efficient of friction
between the road surface and tires is extremely low)
² Depressing the clutch pedal (manual trans.).
² Excessive engine rpm (indicates that the transmission may be in a low gear)
² The VSS signal decreases at a rate of 10 mph (16 kph) per second (indicates that the vehicle may have
decelerated at an extremely high rate)
² If the actual speed is not within 20 mph (32.1 kph) 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 (ECM for diesel).
NOTE: Depressing the OFF switch will erase the set speed stored in the PCM’s/ECM’s RAM.
If, while the speed control is engaged, the driver wishes to increase vehicle speed, the PCM (ECM for diesel) 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/ECM’s RAM when the ACCEL switch is released. The
PCM/ECM also has a 9tap-up9 feature in which vehicle speed increases at a rate of approximately 2 mph (3.2 kph)
for each momentary switch activation of the ACCEL switch.
The PCM/ECM also provides a means to decelerate without 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/ECM’s ON, OFF input, and the battery voltage to
the brake switch.
DR SPEED CONTROL 8P - 9
REMOVAL
Depending on engine control computer (JTEC having
a 3–plug connector or 5.7L V-8 NGC having a
4–plug connector), 2 types of switches are used.
Both types of switches are internally and externally
different. The switches used with the NGC
system have attached pigtail leads. The switch
used with the JTEC system does not have an
attached pigtail lead.
1. Remove switch mounting screw (2).
2. Pull switch (2) from steering wheel.
3. Unplug electrical connector from switch, or, if
equipped, switch pigtail wire harness from steering
wheel wire harness (4) and remove switch.
INSTALLATION
1. Plug electrical connector into switch, or, if equipped, connect pigtail wire harness to steering wheel wire harness.
Be sure wires are not pinched.
2. Position switch to steering wheel.
3. Install switch mounting screw and tighten 15 in. lbs. ( 1.7 N·m).
DESCRIPTION
Two separate switch pods operate the speed control system. The steering-wheel-mounted switches use multiplexed
circuits to provide inputs to the PCM (to the ECM for diesel) 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.
Depending on engine control computer (JTEC having a 3– plug connector or NGC having a 4– plug connector),
2 types of switches are used. Both types of switches are internally and externally different. The
switch used with the NGC system has an attached pigtail lead. The switch used with the JTEC system does
not have an attached pigtail lead.
OPERATION
When speed control is selected by depressing the ON, OFF switch, the PCM (ECM for diesel) 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 (56.2kph) and 85 mph (136.8kph). 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:
² Stepping on the brake pedal
² Depressing the OFF switch
² Depressing the CANCEL switch.
The speed control can be disengaged also by any of the following conditions:
² An indication of Park or Neutral (auto. trans.)
² The VSS signal increases at a rate of 10 mph (16 kph) per second (indicates that the co-efficient of friction
between the road surface and tires is extremely low)
² Depressing the clutch pedal (manual trans.).
² Excessive engine rpm (indicates that the transmission may be in a low gear)
² The VSS signal decreases at a rate of 10 mph (16 kph) per second (indicates that the vehicle may have
decelerated at an extremely high rate)
² If the actual speed is not within 20 mph (32.1 kph) 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 (ECM for diesel).
NOTE: Depressing the OFF switch will erase the set speed stored in the PCM’s/ECM’s RAM.
If, while the speed control is engaged, the driver wishes to increase vehicle speed, the PCM (ECM for diesel) 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/ECM’s RAM when the ACCEL switch is released. The
PCM/ECM also has a 9tap-up9 feature in which vehicle speed increases at a rate of approximately 2 mph (3.2 kph)
for each momentary switch activation of the ACCEL switch.
The PCM/ECM also provides a means to decelerate without 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/ECM’s ON, OFF input, and the battery voltage to
the brake switch.
DR SPEED CONTROL 8P - 9
REMOVAL
Depending on engine control computer (JTEC having
a 3–plug connector or 5.7L V-8 NGC having a
4–plug connector), 2 types of switches are used.
Both types of switches are internally and externally
different. The switches used with the NGC
system have attached pigtail leads. The switch
used with the JTEC system does not have an
attached pigtail lead.
1. Remove switch mounting screw (2).
2. Pull switch (2) from steering wheel.
3. Unplug electrical connector from switch, or, if
equipped, switch pigtail wire harness from steering
wheel wire harness (4) and remove switch.
INSTALLATION
1. Plug electrical connector into switch, or, if equipped, connect pigtail wire harness to steering wheel wire harness.
Be sure wires are not pinched.
2. Position switch to steering wheel.
3. Install switch mounting screw and tighten 15 in. lbs. ( 1.7 N·m).
12-20-2007, 06:53 PM
#13
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I also have this issue, just started last week. Anyone find a fix for a 4.5. It seems to work at lower speeds, say 40 and below. It will cut out if i go up a hill. It does not seem to want to work at highway speeds at all. If I understand correctly there is no vacuum pump under the Battery on the 4.5's. not sure what to check now. any help would be great. thanks.
12-20-2007, 08:26 PM
#14
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I had a simular problem with the cruise it was at the dealer for 3 days and finally found out what was wrong. I had a set of L.E.D. taillights put on that was causing the problem put the stock tail lights back on problem gone.
12-21-2007, 12:32 AM
#15
Registered User
I also have this issue, just started last week. Anyone find a fix for a 4.5. It seems to work at lower speeds, say 40 and below. It will cut out if i go up a hill. It does not seem to want to work at highway speeds at all. If I understand correctly there is no vacuum pump under the Battery on the 4.5's. not sure what to check now. any help would be great. thanks.