Volvo 850. Manual — part 64
connector. Disconnect passenger compartment temperature sensor
connector. Connect jumper wire between temperature sensor connector
terminals No. 2 and 4.
3) Connect an ohmmeter between test unit pins No. 6 and 45
(driver’s side), and between test unit pins No. 6 and 46 (passenger’s
side). If ohmmeter indicates continuity, wiring is okay but intake fan
may have an open circuit. Go to next step. If ohmmeter indicates no
continuity, intake fan is okay but wiring has an open circuit. Repair
wiring as necessary.
4) Ensure ignition is off. Ensure connector from passenger
compartment temperature sensor is disconnected. Connect an ohmmeter
between temperature sensor terminals No. 2 and 4. See Fig. 6. Ohmmeter
should indicate 50,000 ohms. If ohmmeter indicates no continuity,
intake fan has an open circuit. Replace passenger compartment
temperature sensor.
DTC 4-1-4 & 4-1-7 DRIVER’S OR PASSENGER’S SIDE TEMP.
SENSOR INTAKE FAN SEIZED
Turn ignition off. Uncover passenger compartment temperature
sensor. Check if fan turns freely by hand. If fan does not turn
freely, replace fan. Check fan for anything that could cause blockage
and clear as necessary. If fan is okay, replace passenger compartment
temperature sensor.
DTC 4-1-8 NO CONTROL SIGNAL TO ECC POWER STAGE
1) Ensure ignition is off. Connect test unit to ECC control
module. Check ground circuits. See DTC 1-2-1, OUTSIDE TEMP. SENSOR
CIRCUIT SHORTED TO GROUND. If ground circuits are okay, go to next
step.
2) Turn ignition on. Place fan control lever to maximum
speed. Connect voltmeter between test unit pins No. 6 and 42. If 6-8
volts are present, go to next step. If voltmeter indicates zero volts,
wiring is shorted to ground. If voltmeter indicates 12 volts, wiring
is shorted to voltage. Repair wiring as necessary.
3) Ensure ignition is off. Disconnect power stage 4-pin
connector. See Figs. 14 and 15. Connect an ohmmeter between test unit
pin No. 42 and power stage connector terminal 1A. Ohmmeter should
indicate continuity. If no continuity is present, check wiring for an
open circuit.
Fig. 14: Identifying Power Stage Connector Terminals
Courtesy of Volvo Cars of North America.
Fig. 15: Locating Power Stage & A/C Relay
Courtesy of Volvo Cars of North America.
DTC 4-1-9 ECC POWER STAGE EMITTING FAULTY DIAGNOSTIC SIGNAL
1) Ensure ignition is off. Connect test unit to ECC control
module. Check ground circuits. See DTC 1-2-1, OUTSIDE TEMP. SENSOR
CIRCUIT SHORTED TO GROUND. If ground circuits are okay, go to next
step.
2) Turn ignition on. Connect voltmeter between test unit pins
No. 6 and 27. Voltmeter should indicate 3 volts. If voltmeter
indicates one volt, there is no control signal to power stage. See DTC
4-1-8, NO CONTROL SIGNAL TO ECC POWER STAGE. If voltmeter indicates 4
volts, there is excessive voltage from power stage. See DTC 4-1-1,
PASSENGER COMPARTMENT FAN OVERCURRENT OR SEIZED FAN.
3) If voltmeter indicates 12 volts, check wire at ECC control
module terminal A27 (Violet/White wire) for a short to voltage. See
Fig. 10. If voltmeter indicates zero volts, wire has an open circuit
or is shorted to ground. Go to next step.
4) Ensure ignition is off. Disconnect power stage 4-pin
connector. See Figs. 14 and 15. Check Violet/White wire between power
stage connector terminal 2A and ECC control module terminal A27 for a
short to ground or open circuit. If wire is okay, go to next step.
5) Reconnect power stage 4-pin connector. Turn ignition on.
Connect voltmeter between test unit pins No. 6 and 5. If battery
voltage is present, go to next step. If zero volts are present, wire
is shorted to ground.
6) Ensure ignition is off. Disconnect power stage 4-pin
connector. Connect ohmmeter between test unit pin No. 5 and power
stage connector terminal 3A. If ohmmeter indicates continuity, replace
power stage. If ohmmeter indicates no continuity, check wiring for an
open circuit and repair as necessary.
DTC 4-2-0 ECC CONTROL MODULE FAULT, PROGRAM MEMORY
Erase DTC. Start and run engine. Turn engine off, leaving
ignition on. Check if DTC returns. If DTC returns, replace ECC control
module. Perform damper motor limit self-adjustment under TEST MODE 4.
DTC 5-1-1 SELF-ADJUSTMENT OF DAMPER MOTOR
LIMIT POSITIONS NOT CARRIED OUT
Erase DTC. ECC control module is programmed to carry out
self-adjustment of damper motor limit positions. Drive vehicle over 20
MPH for a few minutes. ECC control module will carry out self-
adjustment while driving. Stop vehicle and leave ignition on at least
2 minutes to enable ECC control module to store all values.
TESTING
WARNING: To avoid injury from accidental air bag deployment, read and
carefully follow all SERVICE PRECAUTIONS and DISABLING &
ACTIVATING AIR BAG SYSTEM procedures in the AIR BAG RESTRAINT
SYSTEM article in the ACCESSORIES/SAFETY EQUIPMENT section.
A/C SYSTEM PERFORMANCE
1) Ensure compressor drive belt is okay, fan motor runs at
all speeds, and that temperature vents shut completely with
temperature switch in full cooling position.
2) Ensure that all air comes from panel vents with mode
control on vent position, recirculation motor is working, and
condenser fan and cooling fan are working.
3) Start and warm engine to normal operating temperature.
Ensure compressor clutch engages when A/C is turned on. Set
temperature switch to full cold position, place mode control to vent
position, turn on recirculate air switch and blower fan switch high
speed.
4) Close engine hood, doors and windows. Run engine at 1500-
1600 RPM. Place thermometer in one of the center panel vents. Allow
system to stabilize for at least 8 minutes. Check temperature in
center panel vent. See A/C SYSTEM PERFORMANCE SPECIFICATIONS table.
A/C SYSTEM PERFORMANCE SPECIFICATIONS (1)
Ambient Temp.
F (
C) Outlet Air Temp.
F (
C)
68 (20) . . . . . . . 41-48 (5-8)
86 (30) . . . . . . . 41-48 (5-8)
104 (40) . . . . . . .. 46-54 (8-12)
(1) - Based on a relative humidity of 40-60%.
A/C RELAY CHECK
Remove relay. Connect battery positive lead to relay terminal
No. 1 and negative lead to relay terminal No. 3. Continuity should be
present between relay terminals No. 2 and 4. See Figs. 12 and 15. If
continuity is not present, replace relay.
ON-BOARD DIAGNOSTIC UNIT CHECK
1) Turn ignition on. Press button on diagnostic unit "A". See
Fig. 2. LED should illuminate. If LED does not illuminate, go to next
step. If LED illuminates, but no code(s) is present, go to step 4).
2) Turn ignition off. Remove connector from underside of
diagnostic unit "A". Connect voltmeter between terminal No. 4 of
diagnostic unit "A" and ground. Turn ignition on. Battery voltage
should be present. If battery voltage is present, go to next step. If
battery voltage is not present, check for blown fuse No. 33 or for
open circuit between fuse block and terminal No. 4.
3) Turn ignition off. Connect ohmmeter between terminal No. 8
of diagnostic unit "A" and ground. Continuity should exist. If
continuity exists, replace diagnostic unit and retest. If continuity
does not exist, check ground connection.
4) Turn ignition off. Disconnect selector cable from
diagnostic unit "B". Turn ignition on. Connect voltmeter between
terminal No. 1 of diagnostic unit "B" and ground. Voltage should be
about 10 volts. If voltage is as specified, replace diagnostic unit.
If voltage is not as specified, check for open or shorted circuit
between ECC control module and terminal No. 1 of diagnostic unit "B".
PIN VOLTAGE TESTS
NOTE: Perform all voltage tests using Digital Volt-Ohmmeter (DVOM)
with a minimum 10-megohm input impedance.
Pin voltage chart is supplied to reduce diagnostic time.
Checking pin voltage at ECC control module determines whether it is
receiving or transmitting proper voltage signals. Charts may also help
determine if control unit wiring harness has short or open circuit.
ECC CONTROL MODULE PIN ASSIGNMENTS CONNECTOR "A"
(1)
Function/Description
Voltage Value
Pin No.
1
Power Supply To ECC Control Module
Battery Voltage
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