A/c-Heater System - Automatic: Diagnosis Volvo 850 I

SELF-DIAGNOSTICS

The Electronic Climate Control (ECC) control module can detect faults in the system and store Diagnostic Trouble Codes (DTCs). If a fault is present, system informs driver by flashing the LEDs by the AC and REC switches for 20 seconds.

A fault warning is given when a fault is discovered or present each time ignition is turned on or engine started. DTCs will remain stored until cleared by an input code.

Note. Test Unit (981 3190) and Adapter (981 3194) are required for DTC diagnosis. The Volvo Diagnostic Key (998 8670) may be used to perform self-diagnostics. Follow tool manufacturer's instructions.

There are 3 different test modes/settings which can be selected for reading off DTCs. TEST MODE 1 may be used for reading off DTCs detected by control unit (up to 47 codes can be stored). TEST MODE 2 checks signals from speedometer and solar sensor.

TEST MODE 4 is used to check electrical circuits in A/C system, reset information on damper motor limit positions and change data transmission speed from ECC control module to on-board diagnostic unit.

Note. Ignition must be turned off before switching from one test mode to another.

ENTERING SELF-DIAGNOSTICS

1. Connect selector cable from diagnostic unit "A" to terminal No. 1 of diagnostic unit "B", located behind right headlight. (Scheme 6)
2. Turn ignition on. LED on diagnostic unit "A" should start flashing. Each DTC (3-digits) consists of a series of flashes with a short break between each series. DTCs are displayed in ascending order. See «AUTOMATIC A/C-HEATER SYSTEM DIAGNOSTIC TROUBLE CODES»(ref-13719-S39285282802001032700000).

Scheme 6

AUTOMATIC A/C-HEATER SYSTEM DIAGNOSTIC TROUBLE CODES

TEST MODE 1

1. Turn ignition on. Press button on diagnostic unit "A" for about one second. Read LED flashes. If LED does not illuminate, go to ON-BOARD DIAGNOSTIC UNIT CHECK under TESTING.
2. If LED flashes DTC 1-1-1, no faults are stored. If LED flashes other than DTC 1-1-1, display DTCs and perform appropriate DTC trouble shooting. To erase code, see «ERASING CODES»(ref-13719-S00545649862001032700000) .

TEST MODE 2

1. Turn ignition on. Press button on diagnostic unit "A" twice (for about one second each time). LED should start flashing rapidly once TEST MODE 2 is activated. If LED does not start flashing rapidly after button is pressed, go to «ON-BOARD DIAGNOSTIC UNIT CHECK»(ref-13719-S26858042432001032700000) under TESTING.
2. If LED flashes DTC 1-1-2, signal from solar sensor is okay. If LED flashes DTC 1-1-3, signal from speedometer is okay. If neither DTC is present, go to next step.
3. If DTC 1-1-2 is not present, check solar sensor. Go to SOLAR SENSOR under TESTING. If DTC 1-1-3 is not present, check speed sensor signal. Go to «SPEEDOMETER SIGNAL»(ref-13719-S23707637622001032700000) under TESTING. To exit TEST MODE 2, turn ignition off.

TEST MODE 4

1. Turn ignition on. Press button on diagnostic unit "A" 4 times (for about one second each time). LED should illuminate. If LED illuminates, go to next step. If LED does not illuminate, go to «ON-BOARD DIAGNOSTIC UNIT CHECK»(ref-13719-S26858042432001032700000) under TESTING.
2. Control codes must be entered one step at a time. See «TEST MODE 4 CONTROL CODES»(ref-13719-S16802749602001032700000) . LED should go off after each digit is entered. Entering each digit in a code must be made within 4 seconds, as failure to do so will abort input and TEST MODE 4 must be restarted.

TEST MODE 4 CONTROL CODES

DTC 1-2-1 - OUTSIDE TEMP SENSOR CIRCUIT SHORTED TO GROUND

1. Turn ignition off. Install Test Unit (981 3190) and Adapter (981 3194) between ECC control module and harness connector. (Scheme 7) Using ohmmeter, connect test leads between ground and test unit pins No. 6, 9, 10 and 56. Ohmmeter should read zero ohms in each terminal. If resistance is as specified, go to next step. If resistance is not as specified, check for open circuit.
2. Disconnect Adapter (981 3194) from ECC control module. Disconnect outside temperature sensor (located on right rear of engine compartment). (Scheme 8)- (Scheme 13) and (Scheme 14). Connect ohmmeter leads between test unit pins No. 10 and 14. Ohmmeter should read infinity. If reading is as specified, go to next step. If reading is not as specified, check for shorted circuit between sensor harness connector and ECC control module.
3. Connect ohmmeter leads between outside temperature sensor terminals. Resistance should be 8000-12,000 ohms. If resistance is not as specified, replace outside temperature sensor. Clear and recheck for codes.

Scheme 7

Scheme 8

Scheme 9

Scheme 10

Scheme 11

Scheme 12

Scheme 13

DTC 1-2-2 - OUTSIDE TEMP SENSOR OPEN CKT OR SHORTED TO POWER

1. Ensure DTCs 1-2-2, 1-2-4, 1-2-6, 2-1-1, 2-2-1, 2-3-1, 2-3-3 or 2-3-5 are not present at the same time. If any of these codes are present at the same time, check for an open circuit in the common ground wire. If only DTC 1-2-2 is present, go to next step.
2. Turn ignition off. Install test unit and adapter between ECC control module and harness connector. Using ohmmeter, connect test leads between ground and test unit pins No. 6, 9, 10 and 56. Ohmmeter should read zero ohms in each terminal. If resistance is as specified, go to next step. If resistance is not as specified, check for open circuit.
3. Turn ignition on. Connect voltmeter between test unit pins No. 10 and 14. Check voltage to outside temperature sensor. Voltage should be about 2.6 volts at 68°F (20°C). If voltage reading is 5 volts, check open in circuit or in outside temperature sensor. If voltage reading is 12 volts, check open in circuit between sensor harness terminal No. 1 and ECC control module.
4. Turn ignition off. Disconnect Adapter (981 3194) from ECC control module. Disconnect outside temperature sensor connector (located on right rear of engine compartment). (Scheme 8)- (Scheme 13) and (Scheme 14). Install jumper wire between sensor harness terminals. Connect ohmmeter between test unit pins No. 10 and 14. If ohmmeter reads zero ohms, wire is okay. Check for faulty sensor. If ohmmeter reads infinity, sensor is okay. Check for open circuit.

Scheme 14

DTC 1-2-3 & 1-2-5 - DRIVER'S OR PASSENGER'S SIDE TEMP SENSOR CIRCUIT SHORTED TO GROUND

1. Turn ignition off. Install test unit and adapter between ECC control module and harness connector. Using ohmmeter, connect test leads between ground and test unit pins No. 6, 9, 10 and 56. Ohmmeter should read zero ohms in each terminal. If resistance is as specified, go to next step. If resistance is not as specified, check for open circuit.
2. Disconnect adapter from ECC control module. Disconnect passenger side temperature sensor connector. (Scheme 8)- (Scheme 13) and (Scheme 15). Connect ohmmeter to test unit pins No. 10 and 12 to check driver's side temperature sensor and terminals No. 10 and 13 to check passenger's side temperature sensor.
3. If ohmmeter reads zero ohms, check for short circuit between driver's or passenger's side temperature sensor and ECC control module. See «WIRING DIAGRAMS»(ref-13719-S42386175732001032700000).
4. To check driver's or passenger's side temperature sensor, disconnect harness connector from sensor. Connect ohmmeter between temperature sensor terminal No. 3 (Brown wire) and terminal No. 5 (Green or Yellow wire). Resistance should be 8000-12,000 ohms. If resistance is not as specified, replace faulty temperature sensor.

Scheme 15

DTC 1-2-4 & 1-2-6 - DRIVER'S OR PASSENGER'S SIDE TEMP SENSOR CIRCUIT OPEN OR SHORTED TO POWER

1. Ensure DTCs 1-2-2, 1-2-4, 1-2-6, 2-1-1, 2-2-1, 2-3-1, 2-3-3 or 2-3-5 are not present at the same time. If any of these codes are present at the same time, check for an open circuit in the common ground wire. If only DTC 1-2-4 or 1-2-6 is present, go to next step.
2. Turn ignition off. Install test unit and adapter between ECC control module and wiring harness. Turn ignition on. Connect voltmeter to test unit pins No. 10 and 12 to check driver's side temperature sensor and terminals No. 10 and 13 to check right side temperature sensor.
3. Voltage should be about 2.6 volts at 68°F (20°C). If voltage reading is 5 volts, check for open circuit in passenger's side temperature sensor then go to next step. If voltage reading is 12 volts, repair short circuit between sensor harness terminal No. 5 (Green or Yellow wire) and ECC control module.
4. Turn ignition off. Disconnect Adapter (981 3194) from ECC control module. Disconnect temperature sensor connector. Install jumper wire between sensor harness terminals No. 3 (Brown wire) and No. 5 (Green or Yellow wire).
5. Connect ohmmeter between test unit pins No. 10 and 12 for driver's side temperature sensor or pins No. 10 and 13 for passenger's side temperature sensor. If ohmmeter reads zero ohms, wire is okay. Check for faulty sensor. If ohmmeter reads infinity, sensor is okay. Check for open circuit.
6. To check sensor resistance, disconnect sensor harness connector. Connect ohmmeter between sensor terminals No. 3 (Brown wire) and No. 5 (Green or Yellow wire), resistance should be 8000-12,000 ohms. If resistance is not as specified, replace faulty sensor. Clear and recheck for DTC.

DTC 1-3-1 & 1-3-3 - DRIVER'S OR PASSENGER'S SIDE DUCT TEMP SENSOR CIRCUIT SHORTED TO GROUND

1. Ensure ignition is off. Connect test unit to ECC control module. Check ground circuits and repair as necessary. See DTC 1-2-1, OUTSIDE TEMP. SENSOR CIRCUIT SHORTED TO GROUND. If ground circuits are okay, go to next step.
2. Ensure ignition is off. Disconnect A/C control unit, but leave test unit connected to A/C control unit connector. Disconnect driver's and passenger's side duct temperature sensor connectors. (Scheme 16)
3. Check wiring resistance for driver's side duct temperature sensor by measuring between test unit pins No. 56 and 47. Check wiring resistance for passenger's side duct temperature sensor by measuring between test unit pins No. 56 and 48. If ohmmeter indicates no continuity, go to next step. If ohmmeter indicates continuity, check wiring for short to ground.
4. Ensure ignition is off. Ensure driver's and passenger's side duct temperature sensors are still disconnected. Measure resistance directly between duct temperature sensor terminals. (Scheme 8)- (Scheme 13). Resistance should be about 8000-12,000 ohms. If resistance is not 8000-12,000 ohms, replace duct temperature sensor(s).

Scheme 16

DTC 1-3-2 & 1-3-4 - DRIVER'S OR PASSENGER'S SIDE DUCT TEMP SENSOR CIRCUIT OPEN OR SHORTED TO POWER

1. If DTC 1-3-2 and 1-3-4 are both present, check for open circuit in duct temperature sensor common ground (Brown wire). If DTC 1-3-2 and 1-3-4 are not both present, there is an open or short circuit in wiring between ECC control module and duct temperature sensor. Go to next step.
2. Ensure ignition is off. Connect test unit between ECC control module and A/C system connector. Check ground circuit and repair as necessary. See DTC 1-2-1, OUTSIDE TEMP. SENSOR CIRCUIT SHORTED TO GROUND. If ground circuits are okay, go to next step.
3. Turn ignition on. Check driver's side duct temperature sensor wiring by checking voltage between test unit pins No. 56 and 47. Check passenger's side duct temperature sensor wiring by checking voltage between test unit pins No. 56 and 48. Voltage will vary with duct temperature, but generally should be in 0-3 volt range.
4. If voltmeter indicates 5 volts, check duct temperature sensor wiring for an open circuit. Go to next step. If voltmeter indicates 12 volts, check wiring for short to voltage between connector terminal No. 2 (Green or Yellow wire) and ECC control module terminal C1 (driver's side) or C2 (passenger's side). (Scheme 16)and (Scheme 17).
5. Ensure ignition is off. Disconnect ECC control module, but leave test unit connected to control module connector. Disconnect connector from each duct temperature sensor. Connect jumper wire between duct temperature sensor connector terminals.
6. Check driver's side duct temperature sensor wiring by measuring resistance between test unit pins No. 56 and 47. Check passenger's side duct temperature sensor wiring by measuring resistance between test unit pins No. 56 and 48.
7. If continuity is present, wiring is okay but duct temperature sensor has an open circuit. Replace duct temperature sensor. If continuity is not present, duct temperature sensor is okay but an open circuit is present in wiring. Repair wiring for an open circuit.

Scheme 17

DTC 1-3-5 - NO ENGINE TEMPERATURE FREQUENCY SIGNAL

1. Run engine and check whether temperature gauge in instrument cluster works. If temperature gauge works, engine temperature signal is reaching instrument panel, but Green/Gray wire between ECC control module terminal A23 and instrument cluster has an open circuit. (Scheme 17)
2. If temperature gauge does not work, temperature sensor wiring may be shorted or engine temperature signal may be absent from engine management system.
3. To check wiring, turn ignition off. Check Green/Gray wire between ECC control module terminal A23 and instrument cluster for a short to ground or voltage. If no fault is found, problem may be in engine management system. See appropriate G - TESTS W/ CODES article in the ENGINE PERFORMANCE section below. «TESTS W/CODES - TURBO»(ref-12933) «TESTS W/CODES - NON-TURBO»(ref-12934)

DTC 1-4-1 & 1-4-3 - DRIVER'S OR PASSENGER'S SIDE TEMP SWITCH FAULTY CONTROL SIGNAL

These codes may be caused by an internal fault in ECC control module, temperature switch, or internal wiring. Erase DTCs. Turn ignition off, then on. Test ECC system. See TEST MODE 1 through 4 under FAULT DIAGNOSTICS. Check if DTCs return. If DTCs return, replace ECC control module. Perform self-adjustment of damper motor limit positions under TEST MODE 4.

DTC 1-4-5 - AIR DISTRIBUTION SWITCH FAULTY CONTROL SIGNAL

Code may be caused by an internal fault in ECC control module, air distribution switch, or internal wiring. Erase DTCs. Turn ignition off, then on. Test ECC system. See TEST MODE 1 through 4 under FAULT DIAGNOSTICS. Check if DTCs return. If DTCs return, replace ECC control module. Perform self-adjustment of damper motor limit positions under TEST MODE 4.

DTC 1-5-1 & 1-5-2 - FAN SPEED SENSOR CONTROL SIGNAL MISSING, SIGNAL TOO HIGH OR SIGNAL SHORTED TO GROUND

Codes may be caused by an internal fault in ECC control module, fan speed switch, or internal wiring. Erase DTCs. Turn ignition off, then on. Test ECC system. See TEST MODE 1 through 4 under FAULT DIAGNOSTICS. Check if DTCs return. If DTCs return, replace ECC control module. Perform self-adjustment of damper motor limit positions under TEST MODE 4.

DTC 2-1-1, 2-2-1, 2-3-1, 2-3-3 & 2-3-5 - DRIVER'S OR PASSENGER'S SIDE DAMPER MOTOR POSITION SENSOR CIRCUIT OPEN OR SHORTED TO POWER

1. Check if DTCs 1-2-2, 1-2-4, 1-2-6, 2-1-1, 2-2-1, 2-3-1, 2-3-3 and2-3-5 are present. If all DTCs are not present, there is an open or short circuit in a wire between ECC control unit and damper motor which applies to DTC. See «AUTOMATIC A/C-HEATER SYSTEM DIAGNOSTIC»(ref-13719-S39285282802001032700000) TROUBLE CODES, then go to next step. If all DTCs are present, an open circuit is present in common ground at ECC terminals A9 and A10. (Scheme 17)
2. Ensure ignition is off. Connect test unit between ECC control unit and control unit connector. Check ECC grounds. See DTC 1-2-1, OUTSIDE TEMP. SENSOR CIRCUIT SHORTED TO GROUND. Also check power supply to damper motor position sensor. See «TEST MODE 2»(ref-13719-S35673928022001032700000) under FAULT DIAGNOSTICS. If ECC grounds and power supply to damper motor position sensor are okay, go to next step.
3. Turn ignition on. Connect voltmeter between test unit pins No. 10 and No. 17 (driver's side damper motor), No. 18 (passenger's side damper motor), No. 20 (ventilation damper motor), No. 19 (floor/defrost damper motor), or No. 21 (recirculation damper motor).
4. If voltmeter indicates 12 volts, check wiring and ECC control unit terminals for a short to voltage. See «PIN VOLTAGE TESTS»(ref-13719-S13841737872001032700000) under TESTING. If voltmeter indicates 5 volts, an open circuit is present in wire. Go to next step.
5. Ensure ignition is off. Disconnect ECC control module, but leave test unit connected to ECC connector. Disconnect 6-pin damper motor connector and install a jumper wire between connector terminals No. 1 and 2. (Scheme 8)- (Scheme 13) and (Scheme 18). Connect an ohmmeter between test unit pins No. 10 and 8. If ohmmeter indicates continuity, go to next step. If ohmmeter indicates no continuity, check for open circuit in Brown ground wire.
6. Connect jumper wire between damper motor connector terminals No. 2 and 3. Connect ohmmeter between test unit pins to test respective damper motor. See DAMPER MOTOR TEST UNIT PIN NUMBERS (RESISTANCE CHECK) TABLE. DAMPER MOTOR TEST UNIT PIN NUMBERS (RESISTANCE CHECK) Pin No. Damper Motor 8 & 17 Driver's Side 8 & 18 Passenger's Side 8 & 20 Ventilation 8 & 19 Floor/Defrost 8 & 21 Recirculation
7. If ohmmeter indicates continuity, wiring to damper motor terminal No. 3 is okay, but an open circuit is present in damper motor position sensor. Go to next step. If ohmmeter indicates no continuity, damper motor position sensor is okay, but open circuit is present in wire between damper motor connector terminal No. 3 and ECC control module connector "A".
8. Ensure ignition is off. Disconnect damper motor connector. Connect ohmmeter between terminals No. 1 and 3. (Scheme 8)- (Scheme 13). Turn damper motor output shaft. Ohmmeter should vary between 0-12,000 ohms. If resistance is to specification, go to next step. If resistance is not to specification, there is an open circuit in damper motor position sensor.
9. Connect ohmmeter between damper motor terminals No. 2 and 3. Turn damper motor output shaft. Ohmmeter should vary between 0-12,000 ohms. (Scheme 8)- (Scheme 13). If ohmmeter indicates no continuity, there is an open circuit in damper motor position sensor. Replace damper motor.

Scheme 18

DTC 2-1-2, 2-2-2, 2-3-2, 2-3-4 & 2-3-6 - DRIVER'S OR PASSENGER'S SIDE DAMPER MTR POSITION SENSOR SHORTED TO GROUND

1. Check if DTCs 2-1-2, 2-2-2, 2-3-2, 2-3-4, and 2-3-6 are all present together. If all DTCs are not present, there is a short circuit in ground wire between ECC control unit and damper motor which applies to DTC. See «AUTOMATIC A/C-HEATER SYSTEM DIAGNOSTIC TROUBLE»(ref-13719-S39285282802001032700000) CODES, then go to next step. If all DTCs are present, an open circuit is present in common voltage circuit at ECC terminal A8. (Scheme 17)
2. Ensure ignition is off. Connect test unit between ECC control module and control unit connector. Check ECC grounds. See DTC 1-2-1, OUTSIDE TEMP. SENSOR CIRCUIT SHORTED TO GROUND. Also check power supply to damper motor position sensor. See «TEST MODE 2»(ref-13719-S35673928022001032700000) under FAULT DIAGNOSTICS. If ECC grounds and power supply to damper motor position sensor are okay, go to next step.
3. Turn ignition off. Disconnect ECC control module, but leave test unit connected to ECC control module connector. Disconnect 6-pin damper motor connector. (Scheme 8)- (Scheme 13) and (Scheme 18). Connect ohmmeter between test unit pin No. 10 and pin indicated in «DAMPER MOTOR TEST»(ref-13719-S15211986032001032700000) UNIT PIN NUMBERS (RESISTANCE CHECK). DAMPER MOTOR TEST UNIT PIN NUMBERS (RESISTANCE CHECK) Pin No. Damper Motor 10 & 17 Driver's Side 10 & 18 Passenger's Side 10 & 20 Ventilation 10 & 19 Floor/Defrost 10 & 21 Recirculation
4. If ohmmeter indicates continuity, short circuit is present in wiring at terminal No. 3. If ohmmeter indicates no continuity, wiring is okay. Go to next step.
5. Ensure ignition is off. Disconnect damper motor connector. Connect ohmmeter between damper motor terminals No. 1 and 3. (Scheme 8)-9. Turn damper motor output shaft. Ohmmeter reading should vary between 0-12,000 ohms.
6. If resistance is to specification, check voltage supply circuit between motor connector terminal No. 2 and ECC control module terminal A8. If resistance is a constant zero ohms, a short is present in damper motor position sensor. Replace damper motor.

DTC 3-1-1, 3-1-2, 3-1-3, 3-1-4 & 3-1-5 - DAMPER MOTOR SHORTED TO GROUND OR POWER

1. Turn ignition off. Connect test unit between ECC control module and ECC control module connector. Check system 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 one voltmeter lead to test unit pin No. 10 and other lead to test unit pin No. 31 (driver's damper motor), No. 33 (passenger's side damper motor), No. 37 (ventilation damper motor), No. 35 (floor/defrost damper motor), or No. 39 (recirculation damper motor). Voltmeter should vary from 0-4 volts.
3. If voltmeter indicates zero volts, wire is shorted to ground. If voltmeter indicates battery voltage, wire is shorted to voltage. Turn ignition off. Disconnect suspect damper motor connector. Check wiring between motor connector and EEC control module.

DTC 3-2-1, 3-2-2, 3-2-3, 3-2-4 & 3-2-5 - DAMPER MOTOR ACTIVE TOO LONG

1. Check if DTCs 3-2-1, 3-2-2, 3-2-3, 3-2-4, and 3-2-5 are also present. If all DTCs are present, vehicle may be equipped with an EEC control module for a right-hand-drive vehicle, or vice versa. Check EEC terminal A28. (Scheme 17) ECC control module for left-hand-drive vehicles should not have terminal A28 grounded.
2. If terminal is okay, perform self-adjustment of damper motor limit positions under «TEST MODE 4»(ref-13719-S15212532902001032700000). If motor limit positions are adjusted correctly, check ECC system ground circuits. See DTC 1-2-1, OUTSIDE TEMP. SENSOR CIRCUIT SHORTED TO GROUND. If ground circuits check okay, go to next step.
3. Ensure test unit is connected to ECC control module. Turn ignition on. Connect one voltmeter lead to test unit pin No. 10 and other lead to test unit pin No. 31 (driver's side damper motor), No. 33 (passenger's side damper motor), No. 37 (ventilation damper motor), No. 35 (floor/defrost damper motor), or No. 39 (recirculation damper motor).
4. Rotate air circulation knob to and from different settings while observing voltmeter. Voltmeter should show control voltage of about 0-12 volts while damper is moving to its new setting. If voltmeter shows about 0-12 volts for longer than about 12 seconds, check if damper is stuck in position. Replace damper if not stuck.

DTC 4-1-1 - PASSENGER COMPRTMNT FAN OVERCURRENT OR SEIZED FAN

1. Turn ignition off. Disconnect passenger compartment (blower) fan electrical connector. Check if fan turns freely by hand. If not, replace fan. Check fan location for anything that could cause blockage and clear as necessary.
2. If fan is okay, erase DTC. If DTC returns, there may be a fault in power stage surge protector. See DTC 4-1-9, ECC POWER STAGE EMITTING FAULTY DIAGNOSTIC SIGNAL.

DTC 4-1-2 & 4-1-5 - DRIVER'S OR PASSENGER'S SIDE TEMP SENSOR INTAKE FAN SHORTED TO GROUND

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, turn ignition off. Disconnect test unit from ECC control module, but leave it connected to ECC control module connector. Disconnect passenger compartment temperature sensor connector.
2. Check driver's side fan by connecting an ohmmeter between test unit pins No. 6 and 45. Check passenger's side fan by connecting an ohmmeter between test unit pins No. 6 and 46. If ohmmeter indicates continuity, wiring is shorted to ground or voltage. If ohmmeter indicates no continuity, wiring is okay.
3. Ensure ignition is off. Disconnect passenger compartment temperature sensor connector. Connect an ohmmeter between passenger compartment temperature sensor connector terminals No. 2 and 4. (Scheme 8)-9. Ohmmeter should indicate about 50,000 ohms. If ohmmeter indicates continuity, intake fan is shorted. Replace fan and temperature sensor.

DTC 4-1-3 & 4-1-6 - DRIVER'S OR PASSENGER'S SIDE TEMP SENSOR INTAKE FAN, NO CONTROL VOLTAGE

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. Ensure ignition is off. Disconnect test unit from ECC control module, but leave it connected to ECC control module 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. (Scheme 8)-9. 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 not, 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 Box (981-3190) to ECC control module. Check ground circuits. See 1-2-1 OUTSIDE TEMP. SENSOR GROUND CIRCUIT. 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 reading is below 6 volts, go to step 3. If reading is above 8 volts, go to step 4. If 6-8 volts are present, go to step 5.
3. Wiring is shorted to ground. Check wiring between connector pin 1A and connector B pin B12. (Scheme 19) Repair wiring as necessary and go to step 5.
4. Wiring is shorted to voltage. Check wiring between connector pin 1A and connector B pin B12. (Scheme 19) Repair wiring as necessary and go to next step.
5. Ensure ignition is off. Disconnect power stage 4-pin connector. see scheme 16and (Scheme 20). Connect an ohmmeter between Test Box pin 42 and power stage connector terminal 1A. Ohmmeter should indicate continuity. If no continuity is present, check wiring between connector pin 1A and connect B pin B12 to control unit for an open circuit.

Scheme 19

Scheme 20

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 EEC 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. (Scheme 17) 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 scheme 16and (Scheme 20). 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.