All 3.7L/4.7L/5.9L/8.0LGas Engines and/or Diesel With Automatic Trans.
The speed control system is operated by the use of a cable and a vacuum controlled servo. 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. |
5.7L Gas
The speed control system is fully electronically controlled by the Powertrain Control Module (PCM). 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.
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. |
5.9L Diesel With Manual Trans.
The speed control system is fully electronically controlled by the Engine Control Module (ECM). A cable and a vacuum controlled servo are not used if the vehicle is equipped with a manual transmission and a diesel engine. 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.
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. |
3.7L/4.7L/5.9L/8.0L Gas Powered Engines
3.7L/4.7L/5.9L/8.0L gas powered engines: actual engine vacuum, a vacuum reservoir, a one-way check valve and vacuum lines are used to supply vacuum to the speed control servo.
- Disconnect vacuum hose at speed control servo and install a vacuum gauge into the disconnected hose.
- Start engine and observe gauge at idle. Vacuum gauge should read at least ten inches of mercury.
- If vacuum is less than ten inches of mercury, determine source of leak. Check vacuum line to engine for leaks. Also check actual engine intake manifold vacuum. If manifold vacuum does not meet this requirement, check for poor engine performance and repair as necessary.
- If vacuum line to engine is not leaking, check for leak at vacuum reservoir. To locate and gain access to reservoir, refer to Vacuum Reservoir Removal/Installation in this group. Disconnect vacuum line at reservoir and connect a hand-operated vacuum pump to reservoir fitting. Apply vacuum. Reservoir vacuum should not bleed off. If vacuum is being lost, replace reservoir.
- Verify operation of one-way check valve and check it for leaks. Locate one-way check valve. The valve is located in vacuum line between vacuum reservoir and engine vacuum source. Disconnect vacuum hoses (lines) at each end of valve. Connect a hand-operated vacuum pump to, reservoir end of check valve. Apply vacuum. Vacuum should not bleed off. If vacuum is being lost, replace one-way check valve. Connect a hand-operated vacuum pump to vacuum source end of check valve. Apply vacuum. Vacuum should flow through valve. If vacuum is not flowing, replace one-way check valve. Seal the fitting at opposite end of valve with a finger and apply vacuum. If vacuum will not hold, diaphragm within check valve has ruptured. Replace valve.
5.7 Gas
Vacuum is not used for any part of the speed control system if equipped with a 5.7L V-8 engine.
5.9L Diesel Engine With Manual Trans.
Vacuum is not used for any part of the speed control system if equipped with a diesel engine and a manual transmission.
5.9L Diesel Engines With Automatic Trans.
If equipped with a diesel powered engine and an automatic transmission, an electric vacuum pump and vacuum lines are used to supply vacuum to the speed control servo. A vacuum reservoir is not used.
3.7L/4.7L Gas
- Install end of cable to speed control servo. Refer to Servo Removal/Installation.
- Slide speed control cable plastic mount into throttle body bracket.
- Install speed control cable connector onto throttle body bellcrank pin (push rearward to snap into location).
- Slide throttle (accelerator) cable plastic mount into throttle body bracket. Continue sliding until cable release tab is aligned to hole in throttle body mounting bracket.
- While holding throttle to wide open position, place throttle cable pin into throttle body bellcrank.
- Install air intake tube to top of throttle body.
- Connect negative battery cable at battery.
- Before starting engine, operate accelerator pedal to check for any binding.
5.9L/8.0L Gas
- Install end of cable to speed control servo. Refer to Speed Control Servo Removal/Installation.
- Install cable into throttle body mounting bracket. Cable snaps into bracket.
- Install speed control cable connector at throttle body bellcrank pin. Connector snaps onto pin.
- Install air intake tube to top of throttle body (except 8.0L).
- Connect negative battery cable to battery.
- Before starting engine, operate accelerator pedal to check for any binding.
5.9L Diesel - Auto. Trans.
- Install (connect) end of speed control servo cable to speed control servo. Refer to Speed Control Servo Removal/Installation.
- Install cable through mounting hole on mounting bracket. Cable snaps into bracket.
- Connect servo cable to throttle lever by pushing cable connector rearward onto lever pin while holding lever forward.
- Connect negative battery cables to both batteries.
- Before starting engine, operate accelerator pedal to check for any binding.
- Install cable/lever cover.