Dodge Neon / Neon SRT-4. Manual — part 112

REMOVAL

(1) Disconnect the negative battery cable.
(2) Remove the throttle cable cover.
(3) Remove speed control cable from throttle lever

by sliding clasp out of the hole (Fig. 3).

(4) Lift the retaining tab on the throttle cable and

slide cable out of bracket. Lift the retaining tab on
the speed control cable and slide cable out of bracket.

(5) Disconnect electrical connector from servo.
(6) Disconnect vacuum hose from servo
(7) Remove 2 nuts retaining bracket to servo (Fig.

4).

(8) Remove push nuts holding cable housing to

servo.

(9) Remove retaining clip holding cable to servo

(Fig. 5).

INSTALLATION

(1) Install retaining clip to cable at servo.
(2) Slide cable bell housing over servo mounting

studs.

(3) Install servo mounting studs into bracket.
(4) Install 2 nuts at cable to servo and servo

bracket, tighten to 7 N·m (60 in. lbs.).

(5) Connect electrical connector to servo.
(6) Connect vacuum hose to servo
(7) Rotate the throttle lever forward to the wide

open position and install speed control cable clasp.

(8) Slide speed control cable into throttle cable

bracket and engage retaining tab. Slide throttle cable
into throttle cable bracket and engage retaining tab.

(9) Install the Throttle cable cover.
(10) Connect the negative battery cable.

SERVO

DESCRIPTION

The servo unit consists of a solenoid valve body,

and a vacuum chamber. The solenoid valve body con-
tains three solenoids:

• Vacuum

• Vent

• Dump
The vacuum chamber contains a diaphragm with a

cable attached to control the throttle linkage.

OPERATION

The PCM controls the solenoid valve body. The

solenoid valve body controls the application and
release of vacuum to the diaphragm of the vacuum

Fig. 3 Disconnecting Throttle Cable

Fig. 4 Speed Control Servo

Fig. 5 Speed Control Cable

8P - 4

SPEED CONTROL

PL/SRT-4

CABLE (Continued)

servo. The servo unit cannot be repaired and is ser-
viced only as a complete assembly.

Power is supplied to the servo 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 pro-
vides a safety backup to the vent and vacuum sole-
noids.

The vacuum and vent solenoids must be grounded

by 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 sole-
noid via ground. The vent solenoid opens and closes a
passage to bleed or hold vacuum in the servo as
required.

The PCM cycles the vacuum and vent solenoids to

maintain the set speed, or to accelerate and deceler-
ate 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.

REMOVAL

(1) Disconnect electrical connector from servo (Fig.

6).

(2) Disconnect vacuum hose from servo
(3) Remove 2 nuts retaining bracket to servo.
(4) Remove cable bell housing from servo mounting

studs.

(5) Remove retaining clip pin holding cable to

servo.

INSTALLATION

(1) Install retaining clip to cable at servo.
(2) Install 2 nuts at cable to servo and servo

bracket, tighten to 7 N·m (60 in. lbs.).

(3) Connect electrical connector to servo.
(4) Connect vacuum hose to servo

SWITCH

OPERATION

The speed control system has five separate resis-

tive switches that provide a single multiplexed
(MUX) voltage inputs to the PCM.The switch names
are: ON, OFF, SET, COAST, RESUME, ACCEL, TAP-
UP, COAST, and CANCEL. Based on conditions when
the buttons are pushed (and released), the five volt-
age ranges provided to the PCM result in the follow-
ing functions: ON, OFF, SET, COAST, RESUME,
ACCEL, TAP-UP, TAP-DOWN, COAST, and CAN-
CEL. Refer to the Speed Control Section for more
information

Also the PCM receives an input from the brake

switch to sense whether the brake pedal has been
depressed.

When

the

PCM

receives

the

brake

depressed input, it turns off power to the speed con-
trol servo and disengages speed control. Also the
power to the servo is supplied through the brake
switch, which opens the circuit when the brake pedal
is depressed.

The individual switches cannot be repaired. If one

switch fails, the entire switch module must be
replaced.

REMOVAL

The speed control switches is mounted in the steer-

ing wheel and wired through the clock spring device
under the airbag module (Fig. 7).

Fig. 6 Speed Control Servo

Fig. 7 Speed Control Switch

PL/SRT-4

SPEED CONTROL

8P - 5

SERVO (Continued)

WARNING: IF REMOVAL OF AIRBAG MODULE IS
NECESSARY, REFER TO THE RESTRAINT SYS-
TEMS.

(1) Remove the air cleaner lid, disconnect the inlet

air temperature sensor and makeup air hose.

(2) Remove the negative battery cable.
(3) Turn off ignition.
(4) Remove air bag, refer to the Restraint systems

section.

(5) Remove the top mounting screw (Fig. 8).

(6) Rotate steering wheel so that the switch is in

the 6 o’clock position. Remove 2 screws from the back
side of the speed control switch.

(7) Disconnect the electrical connector.
(8) Remove switch (Fig. 9).

INSTALLATION

The speed control switch is mounted in the steer-

ing wheel and wired through the clock spring device
under the airbag module (Fig. 7).

WARNING: IF REMOVAL OF AIRBAG MODULE IS
NECESSARY, REFER TO THE RESTRAINT SYS-
TEMS.

(1) Connect the electrical connector.
(2) Install switch (Fig. 9) and tighten the screws to

1.6 N·m (15 ins. lbs.). Make sure rubber seal is in
place around switch.

(3) Install airbag, refer to the Restraint Systems

section.

(4) Install the negative battery cable.
(5) Install the air cleaner lid, connect the inlet air

temperature sensor and makeup air hose.

VACUUM RESERVOIR

DESCRIPTION

The vacuum reservoir is located in the engine com-

partment. It is made of plastic.

OPERATION

The reservoir stores engine vacuum. Manifold vac-

uum is supplied from the brake booster check valve.
The speed control vacuum supply hose has a check
valve at the source (brake booster) to maintain the
highest available vacuum level in the servo, reservoir
and vacuum hoses. When engine vacuum drops, as in
climbing a grade while driving, the reservoir supplies
the vacuum needed to maintain proper speed control
operation. The vacuum reservoir cannot be repaired
and must be replaced if faulty.

Fig. 8 Switch Top Mounting Screw

1 - TOP MOUNTING SCREW

Fig. 9 Switch Removal

8P - 6

SPEED CONTROL

PL/SRT-4

SWITCH (Continued)

REMOVAL

(1) Remove the passanger side cowl screen..
(2) Remove vacuum reservoir mounting nuts (Fig.

10).

(3) Remove vacuum hose and throttle cable tie

strap push clip (Fig. 11).

(4) Remove vacuum reservoir.

INSTALLATION

(1) Install vacuum reservoir, install nuts and

tighten to 4.5 N.m (40 in. lbs.) (Fig. 10).

(2) Install vacuum hose.
(3) Install the throttle cable push clip onto reser-

voir (Fig. 11).

NOTE: Throttle cable must be clipped to the reser-
voir to prevent contact with the exhaust manifold.

(4) Install the passenger side cowl screen.

Fig. 10 VACUUM RESERVOIR MOUNTING

Fig. 11 VACUUM RESERVOIR CONNECTIONS

PL/SRT-4

SPEED CONTROL

8P - 7

VACUUM RESERVOIR (Continued)