2000 DODGE NEON Service Repair Manual

DIAGNOSIS AND TESTING
HORN
(1) Disconnect wire connector at horn.
(2) Using a voltmeter, connect one lead to ground
terminal and the other lead to the positive wire ter-
minal (Fig. 3).
(3) Depress the horn switch, battery voltage
should be present.
(4) If no voltage, refer to Horn System Test. If volt-
age is OK, go to Step 5.
(5) Using ohmmeter, test ground wire for continu-
ity to ground.
(6) If no ground repair as necessary.
(7) If wires test OK and horn does not sound,
replace horn.
HORN RELAY
(1) Remove horn relay from Power Distrubution
Center (PDC).
(2) Using ohmmeter, test for continuity between
ground and circuit 65 of horn relay.
(a) When the horn switch is not depressed, no
continuity should be present.
(b) Continuity to ground when horn switch is
depressed.
(c) If continuity is not correct repair horn switch
or wiring as necessary, refer to Group 8W, Wiring
Diagrams.
(3) Insert a jumper wire between circuit 63 and 66
of the Power Distribution Center.
(a) If horn sounds replace relay.
(b) If the horn does not sound, install horn relay
and refer to Horn Test.
(4) Using voltmeter, test voltage at:(a) Circuit 62 and 66 test for battery voltage
from fuse C to body ground.
(b) If voltage is incorrect repair as necessary.
Refer to Group 8W, Wiring Diagrams.
(5) Check relay for 70 to 75 ohms resistance from
terminal 85 to 86 (Fig. 4). If resistance not OK,
replace relay.
HORN SWITCH
(1) Remove horn relay from the Power Distribution
Center.
(2) Using ohmmeter, connect one lead to ground
and the other lead to cavity 65 of the power distribu-
tion center. Refer to Group 8W - Wiring Diagrams.
(3) Depress horn switch, should have continuity. If
no continuity go to Step 4.
(4) Test continuity at horn switch, remove the
Driver Airbag Module. Refer to Driver Airbag Module
Removal and Installation procedures.
(5) Using ohmmeter, connect one lead to the airbag
module ground and the other lead to B+ wire. Refer
to Group 8W - Wiring Diagrams and (Fig. 3).
(6) Depress horn switch, and the meter should
show continuity. If no continuity, replace the Driver
Airbag Module. If OK, repair as necessary.
HORN SYSTEM TEST
Refer to Horn System Test table. If the horn does
not sound, check the horn fuse located in the Power
Distribution Center. If the fuse is blown, replace with
the correct fuse. If the horn fails to sound and the
new fuse blows when depressing the horn switch, a
short circuit in the horn or the horn wiring between
the fuse terminal and the horn is responsible, or a
defective horn switch allowed the horn to burn out is
responsible.
(1) If the fuse is OK, test horn relay. Refer to Horn
Relay Test.
(2) If the relay is OK, test horn. Refer to Horn
Test.
CAUTION: Continuous sounding of horn will cause
horn to fail.
Fig. 3 Horn Harness Connector
Fig. 4 Horn Relay
8G - 2 HORNSPL

Should the horn sound continuously:
²Unplug the horn relay from Power Distribution
Center.²Refer to Horn Relay Test.
Refer to Group 8W, wiring Diagrams for circuit and
wiring information.
HORN SYSTEM TEST
CONDITION POSSIBLE CAUSE CORRECTION
HORN SOUNDS
CONTINUOUSLY.
NOTE:
IMMEDIATELY
UNPLUG HORN
RELAY IN THE
POWER
DISTRIBUTION
CENTER (PDC)(1) FAULTY HORN RELAY.
(2) HORN CONTROL CIRCUIT TO RELAY
SHORTED TO GROUND.
(3) PINCHED HORN SWITCH WIRE
UNDER DRIVER AIRBAG MODULE.
(4) DEFECTIVE HORN SWITCH(1) REFER TO HORN RELAY TEST.
(2) CHECK TERMINAL 65 IN PDC FOR
CONTINUITY TO GROUND. IF
CONTINUITY TO GROUND INDICATES:
(A) STEERING WHEEL HORN SWITCH/
LEAD SHORTED TO GROUND.
(B) WIRING HARNESS SHORTED TO
GROUND. FIND THE SHORT AND REPAIR
AS NECESSARY.
(3) REPLACE DRIVER AIRBAG MODULE.
(4) REPLACE DRIVER AIRBAG MODULE.
HORN SOUND
INTERMITTENTLY
AS THE STEERING
WHEEL IS
TURNED.(1) HORN RELAY CONTROL CIRCUIT X3
IS SHORTED TO GROUND INSIDE
STEERING WHEEL.
(2) PINCHED HORN SWITCH WIRE
UNDER DRIVER AIRBAG MODULE
(3) DEFECTIVE HORN SWITCH(1) REMOVE DRIVER AIRBAG MODULE
AND/OR STEERING WHEEL. CHECK FOR
RUBBING OR LOOSE WIRE/
CONNECTOR, REPAIR AS NECESSARY.
(2) REPLACE DRIVER AIRBAG MODULE.
(3) REPLACE DRIVER AIRBAG MODULE.
HORN DOES NOT
SOUND(1) CHECK FUSE 23 IN PDC
(2) NO VOLTAGE AT HORN RELAY
TERMINALS 62 & 66, AND FUSE IS OK.
(3) OPEN CIRCUIT FROM TERMINAL 65
OF THE HORN RELAY TO HORN
SWITCH X3 CIRCUIT.
(4) DEFECTIVE OR DAMAGED HORN.
(5) DEFECTIVE HORN SWITCH(1) REPLACE FUSE IF BLOWN REPAIR
AS NECESSARY.
(2) NO VOLTAGE, REPAIR PDC AS
NECESSARY.
(3) REPAIR CIRCUIT AS NECESSARY.
(4) VOLTAGE AT HORN WHEN HORN
SWITCH IS PRESSED, REPLACE HORN.
(5) REPLACE DRIVER AIRBAG MODULE.
FUSE BLOWS
WHEN HORN
SOUNDS(1) SHORT CIRCUIT IN HORN OR HORN
WIRING(1) REMOVE HORN RELAY, CHECK FOR
SHORTED HORN OR HORN WIRING.
DISCONNECT HORN WIRE HARNESS TO
ISOLATE SHORT AND REPAIR AS
NECESSARY.
FUSE BLOWS
WITHOUT
BLOWING HORN(1) SHORT CIRCUIT (1) REMOVE RELAY, INSTALL NEW FUSE,
IF FUSE DOES NOT BLOW REPLACE
HORN RELAY. IF FUSE BLOWS WITH
RELAY REMOVED, CHECK FOR SHORT
TO GROUND WITH OHMMETER ON
CIRCUIT BETWEEN TERMINALS 62 & 66
AND THE FUSE TERMINAL. REPAIR AS
NECESSARY.
NOTE: FOR
WIRING REPAIRS
REFER TO GROUP
8W, WIRE
DIAGRAMS.
PLHORNS 8G - 3
DIAGNOSIS AND TESTING (Continued)

REMOVAL AND INSTALLATION
HORN
REMOVAL
(1) Disconnect and isolate the battery negative
cable (Fig. 5).
(2) Remove the windshield washer reservoir. Refer
to Group 8K Windshield Washer and Wipers, Washer
Reservoir Removal and Installation.
(3) Disconnect the harness connector.
(4) Remove the one screw holding the horn assem-
bly to vehicle (Fig. 6).
NOTE: The screw holding the horn assembly is a
captive screw and will remain as part of the assem-
bly.
INSTALLATION
For installation, reverse the above procedures.
HORN RELAY
REMOVAL
(1) Remove the Power Distribution Center cover
and locate the horn relay (Fig. 7).
(2) Remove the horn relay.
INSTALLATION
For installation, reverse the above procedures.
Fig. 5 Battery Negative Cable Remove/Install
1 ± NEGATIVE CABLE
2 ± NEGATIVE BATTERY POST
Fig. 6 Horn Remove/Install
Fig. 7 Power Distribution Center (PDC)
8G - 4 HORNSPL

HORN SWITCH
REMOVAL
(1) Disconnect and isolate the battery negative
cable (Fig. 5).
(2) Remove the Driver Airbag Module. Refer to
Group 8M Passive Restraint Systems, Driver Airbag
Module Removal and Installation.
(3) Clip off strap tie holding the horn switch wire
to the airbag module.
(4) Unclip horn switch wire connector from airbag
module.(5) Remove four torx screws from top side of air-
bag module.
(6) Fold airbag module cover down to expose the
horn switch.
(7) Lift the horn switch off indexing tabs and
remove from vehicle.
INSTALLATION
For installation, reverse the above procedures.
PLHORNS 8G - 5
REMOVAL AND INSTALLATION (Continued)

VEHICLE SPEED CONTROL SYSTEM
TABLE OF CONTENTS
page page
DESCRIPTION AND OPERATION
SPEED CONTROL SYSTEM.................1
SPEED CONTROL SERVO-PCM OUTPUT.......2
SPEED CONTROL SWITCHESÐPCM INPUT....2
STOP LAMP SWITCH......................3
SERVO CABLE...........................3
VACUUM RESERVOIR.....................3VEHICLE SPEED SENSOR..................3
REMOVAL AND INSTALLATION
SPEED CONTROL SERVO...................3
SPEED CONTROL SWITCH..................4
SPEED CONTROL SERVO CABLE.............4
VACUUM RESERVOIR.....................5
DESCRIPTION AND OPERATION
SPEED CONTROL SYSTEM
OPERATION
The speed control system is electronically con-
trolled and vacuum operated. The electronic control
is integrated into the Powertrain Control Module
which is located in the engine compartment. The con-
trols are located on the steering wheel and consist of
five switches. The ON, OFF and SET buttons are
located on the left side of the airbag module. The
RESUME, ACCEL, COAST and CANCEL buttons
are located on the right side of the airbag module
(Fig. 1).
The system is designed to operate at speeds above
25 mph (40 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 SLIP-
PERY.
The speed control can be disengaged manually by:
²Stepping on the brake pedal
²Depressing the OFF switch
²Depressing the CANCEL switch.
The speed control can be disengaged also by any of
the following conditions:
²An indication of Park or Neutral
²The 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)
²Depressing the clutch pedal.
²Excessive engine rpm (indicates that the trans-
mission may be in a low gear)²The VSS signal decreases at a rate of 10 mph
per second (indicates that the vehicle may have
decelerated at an extremely high rate)
²If the actual speed is not within 20 mph of the
set speed
The previous disengagement conditions are pro-
grammed for added safety.
Fig. 1 Speed Control Switch
1 ± SPEED CONTROL SWITCHES
2 ± RES ACCEL
3 ± CANCEL
4 ± COAST
5 ± SET
6 ± ON/OFF
PLVEHICLE SPEED CONTROL SYSTEM 8H - 1

SPEED CONTROL SERVO-PCM OUTPUT
DESCRIPTION
The servo unit consists of a solenoid valve body,
and a vacuum chamber. The solenoid valve body con-
tains three solenoids:
²Vacuum
²Vent
²Dump
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
servo. The servo unit cannot be repaired and is ser-
viced 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 pro-
vides a safety backup to the vent and vacuum sole-
noids.
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 sole-
noid 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 sole-
noids 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 25
mph to resume, 30 mph to set, and the RES/ACCEL
switch has been depressed, ground for the vent and
vacuum circuits is restored.
SPEED CONTROL SWITCHESÐPCM INPUT
Description
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, ACCEL-
ERATE, SET, DECEL and CANCEL modes. Refer tothe 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.
Operation
When speed control is selected by depressing the
ON, OFF switch, the PCM allows a set speed to be
stored in RAM for speed control. To store a set speed,
depress the SET switch while the vehicle is moving
at a speed between 25 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.
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 pro-
grammed 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 RAM when the ACCEL switch is
released. The PCM also has a ªtap-upº feature in
which vehicle speed increases at a rate of approxi-
mately 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 oper-
ates 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 sen-
sor point (open circuit). If a switch with no resistor is
closed, the PCM will measure 0 volts (grounded cir-
cuit). 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.
8H - 2 VEHICLE SPEED CONTROL SYSTEMPL
DESCRIPTION AND OPERATION (Continued)

On most vehicles 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.
STOP LAMP SWITCH
DESCRIPTION
The switch is mounted on the brake pedal mount-
ing bracket under the instrument panel.
OPERATION
Vehicles equipped with the speed control option use
a dual function stop lamp switch. The PCM monitors
the state of the dual function stop lamp switch. Refer
to the Brake section for more information on stop
lamp switch service and adjustment procedures.
The brake switch is equipped with three sets of
contacts, one normally open and the other two nor-
mally closed (brakes disengaged). The PCM sends a
12 volt signal to one of the normally closed contacts
in the brake switch, which is connected to a ground.
With the contacts closed, the 12 volt signal is pulled
to ground causing the signal to go low. The low volt-
age signal, monitored by the PCM, indicates that the
brakes are not applied. When the brakes are applied,
the contacts open, causing the PCM's output voltage
to go high, disengaging the speed control also
grounding the dump solenoid.
The second set of normally closed contacts is sup-
plied battery voltage any time speed control is
selected. From the brake switch, current is routed to
the speed control servo solenoids. The speed control
solenoids (vacuum, vent and dump) are provided this
current any time the speed control is ON and the
brakes are disengaged. When the driver applies the
brakes, the contacts open and current is interrupted
to the solenoids. The normally open contacts are fed
battery voltage. When the brakes are applied, battery
voltage is supplied to the stop lamps.
SERVO CABLE
DESCRIPTION
The speed control servo cable is connected between
the speed control vacuum servo diaphragm and the
throttle body control linkage.
OPERATION
This cable causes the throttle control linkage to
open or close the throttle valve in response to move-
ment of the vacuum servo diaphragm.
VACUUM RESERVOIR
OPERATION
The reservoir stores engine vacuum in the reser-
voir. When engine vacuum drops, as in climbing a
grade while driving, the reservoir supplies the vac-
uum needed to maintain proper speed control opera-
tion. The vacuum reservoir cannot be repaired and
must be replaced if faulty.
VEHICLE SPEED SENSOR
The Vehicle Speed Sensor (VSS) is a pulse genera-
tor mounted to an adapter near the transmission out-
put shaft. The sensor is driven through the adapter
by a speedometer pinion gear. The VSS pulse signal
to the speedometer/odometer is monitored by the
PCM speed control circuitry to determine vehicle
speed and to maintain speed control set speed.
REMOVAL AND INSTALLATION
SPEED CONTROL SERVO
REMOVAL
(1) Disconnect electrical connector from servo (Fig.
2).
(2) Disconnect vacuum hose from servo
(3) Remove 2 nuts retaining cable to servo.
(4) Remove retaining clip pin holding cable to
servo.
Fig. 2 Speed Control Servo
PLVEHICLE SPEED CONTROL SYSTEM 8H - 3
DESCRIPTION AND OPERATION (Continued)