Dodge Dakota (ND). Manual - part 476

The speed control can be disengaged also by any of the following conditions:

•

An indication of Park or Neutral (auto. trans.)

•

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 (manual trans.).

•

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 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 ON, OFF input, and the battery voltage to the
brake switch.

REMOVAL

WARNING: BEFORE ATTEMPTING TO DIAGNOSE,
REMOVE OR INSTALL ANY AIRBAG SYSTEM OR
RELATED

STEERING

WHEEL

AND

STEERING

COLUMN COMPONENTS YOU MUST FIRST DIS-
CONNECT

AND

ISOLATE

THE

NEGATIVE

(GROUND) BATTERY CABLE. WAIT 2 MINUTES
FOR

SYSTEM

CAPACITOR

DISCHARGE

BEFORE FURTHER SYSTEM SERVICE. FAILURE
TO DO SO COULD RESULT IN ACCIDENTAL
DEPLOYMENT

AND

POSSIBLE

PERSONAL

INJURY.

1. Disconnect and isolate negative battery cable from

battery.

2. Remove airbag module. Refer to Restraint Sys-

tems.

3. Unplug electrical connector.

4. Remove speed control switch mounting screw (1)

and remove switch from steering wheel.

INSTALLATION

1. Position switch to steering wheel.

2. Install switch mounting screw and tighten. Refer to torque specifications.

3. Plug electrical connector into switch.

4. Install airbag module. Refer to Restraint Systems.

5. Connect negative battery cable to battery.

8P - 8

SPEED CONTROL

RESERVOIR-VACUUM

DESCRIPTION

The vacuum reservoir (2) is located under the wind-
shield wiper cowel (1).

OPERATION

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.

DIAGNOSIS AND TESTING - VACUUM RESERVOIR

1. Disconnect vacuum hose at speed control servo and install a vacuum gauge into the disconnected hose.

2. Start engine and observe gauge at idle. Vacuum gauge should read at least ten inches of mercury.

3. 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.

4. If vacuum line to engine is not leaking, check for leak at vacuum reservoir. To locate and gain access to reser-

voir, refer to Vacuum Reservoir Removal/Installation in this group. Disconnect vacuum line at reservoir and con-
nect a hand-operated vacuum pump to reservoir fitting. Apply vacuum. Reservoir vacuum should not bleed off. If
vacuum is being lost, replace reservoir.

5. Verify operation of one-way check valve and check it for leaks. Certain models may be equipped with 2

check-valves.

a. 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.

b. 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.

c. 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

SPEED CONTROL

8P - 9