A1 CHECK THE SENSOR RESISTANCE Key in OFF position. Disconnect: In-Vehicle Temperature Sensor C233. Measure the resistance between the in-vehicle temperature sensor terminals. Is the resistance within the specified values for these temperature ranges: 10-20°C (50-68°F), 37,000-58,000 ohms; 20-30°C (68-86°F), 24,000-37,000 ohms; 30-40°C (86-104 °F), 16,000-24,000 ohms? Yes: GO to A2. No: INSTALL a new in-car temperature sensor. TEST the system for normal operation.
A2 CHECK THE EATC SENSOR OUTPUT VOLTAGE Key in ON position. Press the AUTOMATIC button. Measure the voltage between in-vehicle temperature sensor C233-1, circuit 790 (WH/OG) and C233-3, circuit 470 (PK/BK). Is the voltage between 4.7 and 5.1 volts? Yes: INSTALL a new EATC module. TEST the system for normal operation. No: If diagnosing DTC B1251, GO to A3. If diagnosing DTC B1253, GO to 5 .
A3 CHECK CIRCUIT 790 (WH/OG) FOR AN OPEN Key in OFF position. Disconnect: EATC Module C228b. Measure the resistance between EATC module C228b-4, circuit 790 (WH/OG) and in-vehicle temperature sensor C233-1, circuit 790 (WH/OG). Is the resistance less than 5 ohms? Yes: GO to A4. No: REPAIR circuit 790 (WH/OG) for an open. TEST the system for normal operation.
A4 CHECK CIRCUIT 470 (PK/BK) FOR AN OPEN Measure the resistance between EATC module C228b-3, circuit 470 (PK/BK) and in-vehicle temperature sensor C233-3, circuit 470 (PK/BK). Is the resistance less than 5 ohms? Yes: INSTALL a new EATC module. TEST the system for normal operation. No: REPAIR circuit 470 (PK/BK) for an open. TEST the system for normal operation.
A5 CHECK CIRCUIT 790 (WH/OG) FOR A SHORT TO CIRCUIT 470 (PK/BK) Key in OFF position. Disconnect: EATC Module C228b. Measure the resistance between in-vehicle temperature sensor C233-1, circuit 790 (WH/OG) and C233 -3, circuit 470 (PK/BK). Is the resistance greater than 10,000 ohms? Yes: GO to A6. No: REPAIR circuit 790 (WH/OG) for a short to circuit 470 (PK/BK). TEST the system for normal operation.
A6 CHECK CIRCUIT 790 (WH/OG) FOR A SHORT TO GROUND Measure the resistance between EATC module C228b-4, circuit 790 (WH/OG) and ground. Is the resistance greater than 10,000 ohms? Yes: INSTALL a new EATC module. TEST the system for normal operation. No: REPAIR circuit 790 (WH/OG) for a short to ground. TEST the system for normal operation.

An open in circuit 875 (BK/LB) or 468 (BN).
A short to ground in circuit 468 (BN).
Solar radiation sensor.
EATC module.

Scheme 103

Scheme 103: PINPOINT TEST B: DTC B2796 OR DTC B2795 - SOLAR RADIATION SENSOR OPEN CIRCUIT OR SHORT TO GROUND

Scheme 104

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Scheme 107

Scheme 108

B1 CHECK THE SOLAR RADIATION SENSOR RESISTANCE Key in OFF position. Disconnect: Solar Radiation Sensor C286. Measure the resistance between the solar radiation sensor terminals 1 and 5, component side. Is continuity present and the resistance greater than 0 ohms? Yes: GO to B2. No: INSTALL a new solar radiation sensor (19E663). TEST the system for normal operation.
B2 CHECK THE SOLAR RADIATION SENSOR REFERENCE VOLTAGE Key in ON position. Press the AUTOMATIC button. Measure the voltage between solar radiation sensor C286-1, circuit 468 (BN) and C286-5, circuit 875 (BK/LB). Is the voltage between 4.7 and 5.1 volts? Yes: INSTALL a new EATC module (19980). TEST the system for normal operation. No: If diagnosing DTC B2796, GO to B3. If diagnosing DTC B2795, GO to 5 .
B3 CHECK CIRCUIT 875 (BK/LB) FOR AN OPEN Key in OFF position. Measure the resistance between solar radiation sensor C286-5, circuit 875 (BK/LB) and ground. Is the resistance less than 5 ohms? Yes: GO to B4. No: REPAIR circuit 875 (BK/LB) for an open. TEST the system for normal operation.
B4 CHECK CIRCUIT 468 (BN) FOR AN OPEN Disconnect: EATC Module C228b. Measure the resistance between EATC module C228b-14, circuit 468 (BN) and solar radiation sensor C286-1, circuit 468 (BN). Is the resistance less than 5 ohms? Yes: INSTALL a new EATC module. TEST the system for normal operation. No: REPAIR circuit 468 (BN) for an open. TEST the system for normal operation.
B5 CHECK CIRCUIT 875 (BK/LB) FOR A SHORT TO CIRCUIT 468 (BN). Key in OFF position. Disconnect: EATC Module C228b. Measure the resistance between solar radiation sensor C286-5, circuit 875 (BK/LB) and C286-1, circuit 468 (BN). Is the resistance greater than 10,000 ohms? Yes: GO to B6. No: REPAIR circuit 875 (BK/LB) for a short to circuit 468 (BN).
B6 CHECK CIRCUIT 468 (BN) FOR A SHORT TO GROUND Key in OFF position. Disconnect: EATC Module C228b. Measure the resistance between solar radiation sensor C286-1, circuit 468 (BN) and ground. Is the resistance greater than 10,000 ohms? Yes: INSTALL a new EATC module (19980). TEST the system for normal operation. No: REPAIR circuit 468 (BN) for a short to ground. TEST the system for normal operation.

An open, short to voltage, ground or together in circuits 1998 (DB/LG) or 1999 (BN/OG).
Air inlet door actuator.
EATC module.
Manual climate control module.
Stuck or bound linkage or door.

Scheme 109

Scheme 109: PINPOINT TEST C: AIR INLET DOOR INOPERATIVE

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Scheme 116

C1 CHECK THE AIR INLET DOOR ACTUATOR CLOCKWISE OPERATION Disconnect: EMTC Module C294a or EATC module C228a. Remove the door actuator and disengage the actuator driveshaft from the actuator door. Mark the door actuator driveshaft position. Connect a fused jumper wire between EMTC module C294a-8 or EATC module C228a-8, circuit 1998 (DB/LG) and C294a-1 or C228a-1, circuit 875 (BK/LB). Connect a second fused jumper wire between EMTC module C294a-9 or EATC module C228a-9, circuit 1999 (BN/OG) and C294a-26 or C228a-26, circuit 729 (RD/WH). Does the actuator motor move in the clockwise direction? Yes: GO to C2. No: GO to C3.
C2 CHECK THE AIR INLET DOOR ACTUATOR COUNTERCLOCKWISE OPERATION Connect a fused jumper wire between EMTC module C294a-8 or EATC module C228a-8, circuit 1998 (DB/LG) and C294a-26 or C228a -26, circuit 729 (RD/WH). Connect a second fused jumper wire between EMTC module or EATC module EMTC module C294a-9 or EATC module C228a-9, circuit 1999 (BN/OG) and C294a-1 or C228a-1, circuit 875 (BK/LB). Does the actuator motor move in the counterclockwise direction? Yes: INSPECT for binding or broken door and linkage. If no condition is found, INSTALL a new EMTC module or EATC module. TEST the system for normal operation. No: GO to C3.
C3 CHECK CIRCUIT 1998 (DB/LG) FOR A SHORT TO GROUND Disconnect: Recirc Door Actuator C289. Measure the resistance between ground and EMTC module C294a-8 or EATC module C228a-8, circuit 1998 (DB/LG). Is the resistance greater than 10,000 ohms? Yes: GO to C4. No: REPAIR circuit 1998 (DB/LG) for a short to ground. TEST the system for normal operation.
C4 CHECK CIRCUIT 1999 (BN/OG) FOR A SHORT TO GROUND Measure the resistance between ground and EMTC module C294a-9 or EATC module C228a-9, circuit 1999 (BN/OG). Is the resistance greater than 10,000 ohms? Yes: GO to C5. No: REPAIR circuit 1999 (BN/OG) for a short to ground. TEST the system for normal operation.
C5 CHECK CIRCUIT 1998 (DB/LG) FOR A SHORT TO POWER Key in ON position. Measure the voltage between ground and EMTC module C294a-8 or EATC module C228a-8, circuit 1998 (DB/LG). Is voltage present? Yes: REPAIR circuit 1998 (DB/LG) for a short to power. TEST the system for normal operation. No: GO to C6.
C6 CHECK CIRCUIT 1999 (BN/OG) FOR A SHORT TO POWER Measure the voltage between ground and EMTC module C294a-9 or EATC module C228a-9, circuit 1999 (BN/OG). Is voltage present? Yes: REPAIR circuit 1999 (BN/OG) for a short to power. TEST the system for normal operation. No: GO to C7.
C7 CHECK CIRCUIT 1998 (DB/LG) FOR AN OPEN Key in OFF position. Measure the resistance between EMTC module C294a-8 or EATC module C228a-8, circuit 1998 (DB/LG) and recirc door actuator C289-1, circuit 1998 (DB/LG). Is the resistance less than 5 ohms? Yes: GO to C8. No: REPAIR circuit 1998 (DB/LG) for an open. TEST the system for normal operation.
C8 CHECK CIRCUIT 1999 (BN/OG) FOR AN OPEN Measure the resistance between EMTC module C294a-9 or EATC module C228a-9, circuit 1999 (BN/OG) and recirc door actuator C289-6, circuit 1999 (BN/OG). Is the resistance less than 5 ohms? Yes: INSPECT for binding or broken linkage. If no condition is found, INSTALL a new door actuator. TEST the system for normal operation. No: REPAIR circuit 1999 (BN/OG) for an open. TEST the system for normal operation.

An open, short to voltage, ground or together in door actuator open, close, return, reference or feedback circuits.
Blend, air inlet, floor/defrost and panel mode door actuator motor.
EATC module.
Manual climate control module.
Stuck or bound linkage or door.

Scheme 117

Scheme 117: PINPOINT TEST D: INCORRECT/ERRATIC DIRECTION OF AIRFLOW FROM OUTLET(S)

Scheme 118

Scheme 119

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Scheme 139

Scheme 140

D1 CHECK THE AIRFLOW Key in ON position. Check the air discharge temperature in full COOL and full WARM and airflow in the MAX A/C, PANEL, DEFROST and FLOOR modes. Is the air discharge temperature and airflow correct in each setting? Yes: The system is operating normally. No: For electronic automatic temperature control (EATC) systems: DTC B1263, B1264 or B2266, GO to D2. For EMTC systems: If the airflow is from the panel only, floor and defrost ducts only (no panel) or some panel while in defrost or floor mode, follow diagnostics for panel door actuator. GO to D2. If the airflow is from the panel and defrost only, panel and floor only, defrost and floor in defrost mode or defrost and floor in floor mode, follow diagnostics for floor/defrost door actuator. GO to D2. If the temperature control is inoperative/does not operate correctly, follow diagnostics for the blend door actuator. GO to D2. If the MAX A/C button does not change the air inlet door position, Go To «PINPOINT TEST C: AIR INLET DOOR INOPERATIVE»(ref-206745-S25498641872005112600000) .
D2 CHECK THE FEEDBACK POTENTIOMETER TOTAL RESISTANCE Disconnect: EATC Module C228a or EMTC Module C294a. Disconnect: For DTC B1263 or Panel Door Actuator, Temperature Blend Door Actuator C2092 and Floor/Defrost Door Actuator C234. Disconnect: For DTC B1264 or Floor/Defrost Door Actuator, Temperature Blend Door Actuator C2092 and Panel Door Actuator C236. Disconnect: For DTC B2266 or Blend Door Actuator, Floor/Defrost Door Actuator C234 and Panel Door Actuator C236. Remove the door actuator and disengage the actuator driveshaft from the actuator door. Mark the door actuator driveshaft position. Measure the resistance between EATC module C228a-5 or EMTC module C294a-5, circuit 243 (LG/OG) and EATC module C228a-15 or EMTC module C294a -15, circuit 247 (WH/YE). Is the resistance between 5,000 and 6,000 ohms? Yes: GO to D3. No: If the resistance is greater than 6,000 ohms, GO to D5. If the resistance is less than 5,000 ohms, GO to D7.
D3 CHECK THE POTENTIOMETER LOW SIDE RESISTANCE Measure the resistance between EATC module C228a-15 or EMTC module C294a-15, circuit 247 (WH/YE) and the following: For DTC B1263 or panel door actuator, EATC module C228a-16 or EMTC module C294a -16, circuit 1989 (OG/LB). For DTC B1264 or floor/defrost door actuator, EATC module C228a-17 or EMTC module C294a -17, circuit 1990 (WH/LB). For DTC B2266 or blend door actuator, EATC module C228a-18 or EMTC module C294a -18, circuit 246 (VT). Is the resistance between 250 and 5,500 ohms? Yes: GO to D4. No: If the resistance is greater than 5,500 ohms, GO to D8. If the resistance is less than 250 ohms, GO to D9.
D4 CHECK THE POTENTIOMETER HIGH SIDE RESISTANCE Measure the resistance between EATC module C228a-5 or EMTC module C294a-5, circuit 243 (LG/OG) and the following: For DTC B1263 or panel door actuator, EATC module C228a-16 or EMTC module C294a -16, circuit 1989 (OG/LB). For DTC B1264 or floor/defrost door actuator, EATC module C228a-17 or EMTC module C294a -17, circuit 1990 (WH/LB). For DTC B2266 or blend door actuator, EATC module C228a-18 or EMTC module C294a -18, circuit 246 (VT). Is the resistance between 20 and 5,500 ohms? Yes: GO to D11. No: If the resistance is greater than 5,500 ohms, INSTALL a new door actuator. TEST the system for normal operation. If the resistance is less than 250 ohms, GO to D10.
D5 CHECK CIRCUIT 243 (LG/OG) FOR AN OPEN Disconnect: For DTC B1263, Panel Door Actuator C236. Disconnect: For DTC B1264, Floor/Defrost Door Actuator C234. Disconnect: For DTC B2266, Blend Door Actuator C2092. Measure the resistance between EATC module C228a-5 or EMTC module C294a-5, circuit 243 (LG/OG) and the following: For DTC B1263 or panel door actuator C236-3, circuit 243 (LG/OG). For DTC B1264 or floor/defrost door actuator C234-3, circuit 243 (LG/OG). For DTC B2266 or blend door actuator C2092-3, circuit 243 (LG/OG). Is the resistance less than 5 ohms? Yes: GO to D6. No: REPAIR circuit 243 (LG/OG) for an open. TEST the system for normal operation.
D6 CHECK THE ACTUATOR RETURN CIRCUIT 247 (WH/YE) FOR AN OPEN Measure the resistance between EATC module C228a-15 or EMTC module C294a-15, circuit 247 (WH/YE) and the following: For DTC B1263 or panel door actuator C236-2, circuit 247 (WH/YE). For DTC B1264 or floor/defrost door actuator C234-2, circuit 247 (WH/YE). For DTC B2266 or blend door actuator C2092-2, circuit 247 (WH/YE). Is the resistance less than 5 ohms? Yes: INSTALL a new door actuator. TEST the system for normal operation. No: REPAIR circuit 247 (WH/YE) for an open. TEST the system for normal operation.
D7 CHECK CIRCUIT 247 (WH/YE) AND CIRCUIT 243 (LG/OG) FOR A SHORT TOGETHER Disconnect: For DTC B1263, Panel Door Actuator C236. Disconnect: For DTC B1264, Floor/Defrost Door Actuator C234. Disconnect: For DTC B2266, Blend Door Actuator C2092. Measure the resistance between EATC module C228a-5 or EMTC module C294a-5, circuit 243 (LG/OG) and EATC module C228a-15 or EMTC module C294a -15, circuit 247 (WH/YE). Is the resistance greater than 10,000 ohms? Yes: INSTALL a new door actuator. TEST the system for normal operation. No: REPAIR circuit 247 (WH/YE) and circuit 243 (LG/OG) for a short together. TEST the system for normal operation.
D8 CHECK CIRCUIT 1989 (OG/LB), 1990 (WH/LB) OR CIRCUIT 246 (VT) FOR AN OPEN Disconnect: For DTC B1263, Panel Door Actuator C236. Disconnect: For DTC B1264, Floor/Defrost Door Actuator C234. Disconnect: For DTC B2266, Blend Door Actuator C2092. Measure the resistance between the following: For DTC B1263 or panel door actuator, EATC module C228a-16 or EMTC module C294a -16, circuit 1989 (OG/LB) and panel door actuator C236-4, circuit 1989 (OG/LB). For DTC B1264 or floor/defrost door actuator, EATC module C228a-17 or EMTC module C294a -17, circuit 1990 (WH/LB) and floor/defrost door actuator C234- 4, circuit 1990 (WH/LB). For DTC B2266 or blend door actuator, EATC module C228a-18 or EMTC module C294a -18, circuit 246 (VT) and floor door actuator C2092-4, circuit 246 (VT). Is the resistance less than 5 ohms? Yes: INSTALL a new door actuator. TEST the system for normal operation. No: REPAIR circuit 1989 (OG/LB),1990 (WH/LB) or circuit 246 (VT) for an open. TEST the system for normal operation.
D9 CHECK CIRCUIT 247 (WH/YE) FOR A SHORT TO CIRCUITS 1989 (OG/LB), 1990 (WH/LB) OR 246 (VT) Disconnect: For DTC B1263, Panel Door Actuator C236. Disconnect: For DTC B1264, Floor/Defrost Door Actuator C234. Disconnect: For DTC B2266, Blend Door Actuator C2092. Measure the resistance between EATC module C228a-15 or EMTC module C294a-15, circuit 247 (WH/YE) and the following: For DTC B1263 or panel door actuator, EATC module C228a-16 or EMTC module C294a -16, circuit 1989 (OG/LB). For DTC B1264 or floor/defrost door actuator, EATC module C228a-17 or EMTC module C294a -17, circuit 1990 (WH/LB). For DTC B2266 or blend door actuator, EATC module C228a-18 or EMTC module C294a -18, circuit 246 (VT). Is the resistance greater than 10,000 ohms? Yes: INSTALL a new door actuator. TEST the system for normal operation. No: REPAIR circuit 247 (WH/YE) and circuits 1989 (OG/LB), 1990 (WH/LB) or 246 (VT) for a short together. TEST the system for normal operation.
D10 CHECK CIRCUIT 243 (LG/OG) FOR A SHORT TO CIRCUITS 1989 (OG/LB), 1990 (WH/LB) OR CIRCUIT 246 (VT) Disconnect: For DTC B1263, Panel Door Actuator C236. Disconnect: For DTC B1264, Floor/Defrost Door Actuator C234. Disconnect: For DTC B2266, Blend Door Actuator C2092. Measure the resistance between EATC module C228a-5 or EMTC module C294a-5, circuit 243 (LG/OG) and the following: For DTC B1263 or panel door actuator, EATC module C228a-16 or EMTC module C294a -16, circuit 1989 (OG/LB). For DTC B1264 or floor/defrost door actuator, EATC module C228a-17 or EMTC module C294a -17, circuit 1990 (WH/LB). For DTC B2266 or blend door actuator, EATC module C228a-18 or EMTC module C294a -18, circuit 246 (VT). Is the resistance greater than 10,000 ohms? Yes: INSTALL a new door actuator. TEST the system for normal operation. No: REPAIR circuits 243 (LG/OG) and circuits 1989 (OG/LB), 1990 (WH/LB) or 246 (VT) for a short together. TEST the system for normal operation.
D11 CHECK CIRCUIT 243 (LG/OG), 246 (VT), 1989 (OG/LB) OR 1990 (WH/LB) FOR A SHORT TO GROUND Disconnect: For DTC B1263, Panel Door Actuator C236. Disconnect: For DTC B1264, Floor/Defrost Door Actuator C234. Disconnect: For DTC B2266, Blend Door Actuator C2092. Measure the resistance between ground and the following: EATC Module C228a-5 or EMTC module C294a-5, circuit 243 (LG/OG). For DTC B1263 or panel door actuator, EATC module C228a-16 or EMTC module C294a -16, circuit 1989 (OG/LB). For DTC B1264 or floor/defrost door actuator, EATC module C228a-17 or EMTC module C294a -17, circuit 1990 (WH/LB). For DTC B2266 or blend door actuator, EATC module C228a-18 or EMTC module C294a -18, circuit 246 (VT). Is the resistance greater than 10,000 ohms? Yes: GO to D12 No: REPAIR circuit(s) for a short to ground. TEST the system for normal operation.
D12 CHECK CIRCUITS 247 (WH/YE), 246 (VT), 1989 (OG/LB) OR 1990 (WH/LB) FOR A SHORT TO POWER Key in ON position. Measure the voltage between ground and the following: EATC module C228a-15 or EMTC module C294a -15, circuit 247 (WH/YE). For DTC B1263 or panel door actuator, EATC module C228a-16 or EMTC module C294a -16, circuit 1989 (OG/LB). For DTC B1264 or floor/defrost door actuator, EATC module C228a-17 or EMTC module C294a -17, circuit 1990 (WH/LB). For DTC B2266 or blend door actuator, EATC module C228a-18 or EMTC module C294a -18, circuit 246 (VT). Is voltage present? Yes: REPAIR circuit(s) for a short to power. TEST the system for normal operation. No: GO to D13.
D13 CHECK THE DOOR ACTUATOR CLOCKWISE OPERATION Connect a fused jumper wire between EATC module C228a-26 or EMTC module C294a-26, circuit 729 (RD/WH) and : For DTC B1263 or panel door actuator, EATC module C228a-20 or EMTC module C294a -20, circuit 1993 (BN/YE). For DTC B1264 or floor/defrost door actuator, EATC module C228a-25 or EMTC module C294a -25, circuit 1997 (BN/YE). For DTC B2266 or blend door actuator, EATC module C228a-7 or EMTC module C294a-7, circuit 250 (OG). Connect a second fused jumper wire between EATC module C228a-1 or EMTC module C294a-1, circuit 875 (BK/LB) and: For DTC B1263 or panel door actuator, EATC module C228a-19 or EMTC module C294a -19, circuit 1992 (YE/LB). For DTC B1264 or floor/defrost door actuator, EATC module C228a-24 or EMTC module C294a -24, circuit 1996 (LB/RD). For DTC B2266 or blend door actuator, EATC module C228a-6 or EMTC module C294a-6, circuit 249 (DB/LG). Does the actuator motor move in the clockwise direction? Yes: GO to D14. No: GO to D15.
D14 CHECK THE DOOR ACTUATOR COUNTERCLOCKWISE OPERATION Connect a fused jumper wire between EATC module C228a-1 or EMTC module C294a-1, circuit 875 (BK/LB) and : For DTC B1263 or panel door actuator, EATC module C228a-20 or EMTC module C294a -20, circuit 1993 (BN/YE). For DTC B1264 or floor/defrost door actuator, EATC module C228a-25 or EMTC module C294a -25, circuit 1997 (BN/YE). For DTC B2266 or blend door actuator, EATC module C228a-7 or EMTC module C294a-7, circuit 250 (OG). Connect a second fused jumper wire between EATC module C228a-26 or EMTC module C294a -26, circuit 729 (RD/WH) and: For DTC B1263 or panel door actuator, EATC module C228a-19 or EMTC module C294a -19, circuit 1992 (YE/LB). For DTC B1264 or floor/defrost door actuator, EATC module C228a-24 or EMTC module C294a -24, circuit 1996 (LB/RD). For DTC B2266 or blend door actuator, EATC module C228a-6 or EMTC module C294a-6, circuit 249 (DB/LG). Does the actuator motor move in the counterclockwise direction? Yes: Inspect for binding or broken door and linkage. IF no condition is found, INSTALL a new EATC module or EMTC module. TEST the system for normal operation. No: GO to D15
D15 CHECK THE ACTUATOR MOTOR DRIVE CIRCUITS FOR AN OPEN Disconnect: For DTC B1263, Panel Door Actuator C236. Disconnect: For DTC B1264, Floor/Defrost Door Actuator C234. Disconnect: For DTC B2266, Blend Door Actuator C2092. Measure the resistance between: For DTC B1263 or panel door actuator, EATC module C228a-20 or EMTC module C294a -20, circuit 1993 (BN/YE) and panel door actuator C236-6, circuit 1993 (BN/YE). For DTC B1264 or floor/defrost door actuator, EATC module C228a-25 or EMTC module C294a -25, circuit 1997 (BN/YE) and floor/defrost door actuator C234-6, circuit 1997 BN/YE). For DTC B2266 or blend door actuator, EATC module C228a-7 or EMTC module C294a-7, circuit 250 (OG) and blend door actuator C2092-6, circuit 250 (OG). Measure the resistance between: For DTC B1263 or panel door actuator, EATC module C228a-19 or EMTC module C294a -19, circuit 1992 (YE/LB) and panel door actuator C236-1, circuit 1992 (YE/LB). For DTC B1264 or floor/defrost door actuator, EATC module C228a-24 or EMTC module C294a -24, circuit 1996 (LB/RD) and floor/defrost door actuator C234-1, circuit 1996 (LB/RD). For DTC B2266 or blend door actuator, EATC module C228a-6 or EMTC module C294a-6, circuit 249 (DB/LG) and blend door actuator C2092-1, circuit 249 (DB/LG). Are the resistances less than 5 ohms? Yes: GO to D16. No: REPAIR the circuit(s) for an open. TEST the system for normal operation.
D16 CHECK THE ACTUATOR MOTOR DRIVE CIRCUITS FOR A SHORT TO GROUND Measure the resistance between ground and: For DTC B1263 or panel door actuator, EATC module C228a-20 or EMTC module C294a -20, circuit 1993 (BN/YE). For DTC B1264 or floor/defrost door actuator, EATC module C228a-25 or EMTC module C294a -25, circuit 1997 (BN/YE). For DTC B2266 or blend door actuator, EATC module C228a-7 or EMTC module C294a-7, circuit 250 (OG). Measure the resistance between ground and: For DTC B1263 or panel door actuator, EATC module C228a-19 or EMTC module C294a -19, circuit 1992 (YE/LB). For DTC B1264 or floor/defrost door actuator, EATC module C228a-24 or EMTC module C294a -24, circuit 1996 (LB/RD). For DTC B2266 or blend door actuator, EATC module C228a-6 or EMTC module C294a-6, circuit 249 (DB/LG). Are the resistances greater than 10,000 ohms? Yes: GO to D17. No: REPAIR the circuit(s) for a short to ground. TEST the system for normal operation.
D17 CHECK THE ACTUATOR MOTOR DRIVE CIRCUITS FOR A SHORT TO POWER Key in ON position. Measure the voltage between ground and: For DTC B1263 or panel door actuator, EATC module C228a-20 or EMTC module C294a -20, circuit 1993 (BN/YE). For DTC B1264 or floor/defrost door actuator, EATC module C228a-25 or EMTC module C294a -25, circuit 1997 (BN/YE). For DTC B2266 or blend door actuator, EATC module C228a-7 or EMTC module C294a-7, circuit 250 (OG). Measure the voltage between ground and: For DTC B1263 or panel door actuator, EATC module C228a-19 or EMTC module C294a -19, circuit 1992 (YE/LB). For DTC B1264 or floor/defrost door actuator, EATC module C228a-24 or EMTC module C294a -24, circuit 1996 (LB/RD). For DTC B2266 or blend door actuator, EATC module C228a-6 or EMTC module C294a-6, circuit 249 (DB/LG). Is voltage present? Yes: REPAIR the circuit(s) for a short to power. TEST the system for normal operation. No: GO to D18. D18 CHECK THE ACTUATOR MOTOR DRIVE CIRCUITS FOR A SHORT TOGETHER Key in OFF position. NOTE: For DTC B1263 or panel door actuator. Measure the resistance between EATC module C228a-19 or EMTC module C294a-19, circuit 1992 (YE/LB) and EATC module C228a-20 or EMTC module C294a -20, circuit 1993 (BN/YE). NOTE: For DTC B1264 or floor/defrost door actuator. Measure the resistance between EATC module C228a-24 or EMTC module C294a-24, circuit 1996 (LB/RD) and EATC module C228a-25 or EMTC module C294a -25, circuit 1997 (BN/YE). NOTE: For DTC B2266 or blend door actuator. Measure the resistance between EATC Module C228a-6 or EMTC Module C294a-6, circuit 249 (DB/LG) and EATC Module C228a-7 or EMTC Module C294a-7, circuit 250 (OG). Is the resistance greater than 10,000 ohms? Yes: INSPECT for binding or broken linkage. If no condition is found, INSTALL a new door actuator. TEST the system for normal operation. No: REPAIR circuit(s) for a short together. TEST the system for normal operation.

An open in circuit 848 (DG/OG) or circuit 1069 (OG/LB).
A short to ground or voltage in circuit 1069 (OG/LB).
Steering wheel control switch.
EATC module.
PCM.
Clockspring.

An open in circuit 875 (BK/LB), 729 (RD/WH) or 296 (WH/VT).
EATC module.

Scheme 141

Scheme 141: PINPOINT TEST F: NO COMMUNICATION WITH THE ELECTRONIC AUTOMATIC TEMPERATURE CONTROL (EATC) MODULE

Scheme 142

F1 CHECK CIRCUIT 875 (BK/LB) FOR AN OPEN Key in OFF position. Disconnect: EATC Module C228a. Measure the resistance between EATC module C228a-1, circuit 875 (BK/LB) and ground. Is the resistance less than 5 ohms? Yes: GO to F2. No: REPAIR circuit 875 (BK/LB). TEST the system for normal operation.
F2 CHECK CIRCUITS 729 (RD/WH) AND 296 (WH/VT) FOR AN OPEN Key in ON position. Measure the voltage between EATC module C228a-26, circuit 729 (RD/WH), C228a-14, circuit 296 (WH/VT) and ground. Is the voltage greater than 10 volts? Yes GO to «MODULE COMMUNICATIONS NETWORK»(ref-206750) to diagnose the network concern. No: REPAIR circuit 729 (RD/WH) or circuit 296 (WH/VT) for an open. TEST the system for normal operation.

An open in circuit 875 (BK/LB), 729 (RD/WH) or 296 (WH/VT).
EATC module.

Scheme 143

Scheme 143: PINPOINT TEST G: THE EATC SYSTEM IS INOPERATIVE, INTERMITTENT OR INCORRECT OPERATION

Scheme 144

G1 VERIFY AUTOMATIC OPERATION Key in ON position. With engine running, press the AUTOMATIC button. Does the indicator above the AUTO button illuminate and the selected temperature appear in the display window? Yes: GO to G2. No: GO to G11.
G2 CARRY OUT THE EATC MODULE SELF-TEST Key in ON position. Carry out the EATC module self-test. Refer to the «ELECTRONIC AUTOMATIC TEMPERATURE CONTROL MODULE ON-DEMAND SELF-TEST»(ref-206745-S36013073722005112600000) . Record the DTCs displayed, if any. Were any DTCs displayed as a result of the EATC self-test? Yes: REFER to the «ELECTRONIC AUTOMATIC TEMPERATURE CONTROL (EATC) MODULE DIAGNOSTIC TROUBLE CODE (DTC) INDEX»(ref-206745-S20614298312005112600000) . CARRY OUT the necessary diagnosis and REPAIR as required. No: GO to G3.
G3 CHECK THE VACUUM FLUORESCENT DISPLAY Exit the self-test by pressing the DEFROST button. Observe the button indicators and function symbols displayed on the vacuum fluorescent display while changing the temperature, blower speed and functions. Are the display and indicators correct and complete without any missing elements? Yes: GO to G4. No: INSTALL a new EATC module. TEST the system for normal operation.
G4 CHECK THE BLOWER MANUAL OVERRIDE OPERATION Press the blower motor speed override control fully up and fully down. Does the blower motor speed increase from low speed to high and high speed to low? Yes: GO to G5. No: If the blower motor is inoperative, Go To «PINPOINT TEST M: THE BLOWER MOTOR IS INOPERATIVE - EATC»(ref-206745-S42868314392005112600000) . If the blower motor does not operate correctly, Go To «PINPOINT TEST N: THE BLOWER MOTOR DOES NOT OPERATE CORRECTLY - EATC»(ref-206745-S25725216122005112600000) .
G5 VERIFY THE DEFROST OVERRIDE OPERATION Press the override button for DEFROST operation. Is outside air being discharged from the windshield defroster nozzle and the side window demisters? Yes: GO to G6. No: Go To «PINPOINT TEST D: INCORRECT/ERRATIC DIRECTION OF AIRFLOW FROM OUTLET(S)»(ref-206745-S42175074982005112600000) .
G6 VERIFY THE FLOOR OVERRIDE OPERATION Press the override button for FLOOR operation. Is outside air being discharged from the floor duct? Yes: GO to G7. No: Go To «PINPOINT TEST D: INCORRECT/ERRATIC DIRECTION OF AIRFLOW FROM OUTLET(S)»(ref-206745-S42175074982005112600000) .
G7 VERIFY THE PANEL OVERRIDE OPERATION Press the override button for PANEL operation. Is outside air being discharged from the instrument panel registers? Yes: GO to G8. No: Go To «PINPOINT TEST D: INCORRECT/ERRATIC DIRECTION OF AIRFLOW FROM OUTLET(S)»(ref-206745-S42175074982005112600000) .
G8 VERIFY THE A/C CLUTCH DOES NOT ENGAGE IN THE PANEL MODE In PANEL operation and the A/C OFF, listen for the compressor clutch to engage. Does the A/C clutch engage with the PANEL override button pressed? Yes: GO to «PINPOINT TEST J: THE AIR CONDITIONING (A/C) IS ALWAYS ON»(ref-206745-S10394547182005112600000) . No: GO to G9.
G9 VERIFY A/C CLUTCH ENGAGEMENT IN THE A/C MODE Make sure the ambient air temperature is above 2°C (35°F). Press the override button for A/C operation. Does the A/C clutch engage when the A/C override button is pressed? Yes: GO to G10. No: Go To «PINPOINT TEST I: THE A/C DOES NOT OPERATE/DOES NOT OPERATE CORRECTLY»(ref-206745-S00528088472005112600000) .
G10 VERIFY THE RECIRC OVERRIDE OPERATION Press the PANEL and RECIRC override buttons. Is recirculated air being discharged from the instrument panel registers? Yes: The test is complete. The system is functioning normally. No: Go To «PINPOINT TEST C: AIR INLET DOOR INOPERATIVE»(ref-206745-S25498641872005112600000) .
G11 CHECK THE EATC MODULE FUNCTIONS Press each function button and observe the display. Does the EATC carry out and display any functions? Yes: INSTALL a new EATC module. TEST the system for normal operation. No: GO to G12.
G12 CHECK CIRCUIT 875 (BK/LB) FOR AN OPEN Key in OFF position. Disconnect: EATC Module C228a. Measure the resistance between EATC module C228a-1, circuit 875 (BK/LB) and ground. Is the resistance less than 5 ohms? Yes: GO to G13. No: REPAIR circuit 875 (BK/LB). TEST the system for normal operation.
G13 CHECK CIRCUITS 729 (RD/WH) AND 296 (WH/VT) FOR AN OPEN Key in ON position. Measure the voltage between EATC module C228a-26, circuit 729 (RD/WH), C228a-14, circuit 296 (WH/VT) and ground. Is the voltage greater than 10 volts? Yes: INSTALL a new EATC module. TEST the system for normal operation. No: REPAIR circuit 729 (RD/WH) or 296 (WH/VT) for an open. TEST the system for normal operation.

Plugged heater core.
Coolant level.
Temperature blend door.

Scheme 145

Scheme 145: PINPOINT TEST H: INSUFFICIENT, ERRATIC OR NO HEAT

Scheme 146

H1 CHECK FOR CORRECT ENGINE COOLANT LEVEL Key in OFF position. Check the engine coolant level when hot and cold. Is the engine coolant at the correct level (hot/cold) as indicated on the engine coolant recovery reservoir? Yes: GO to H3. No: GO to H2.
H2 CHECK THE ENGINE COOLING SYSTEM FOR LEAKS Pressure test the cooling system for leaks. Refer to «ENGINE COOLING - F150 PICKUP»(ref-206738) . Does the engine cooling system leak? Yes: REPAIR the engine coolant leak. TEST the system for normal operation. No: GO to H3.
H3 CHECK FOR COOLANT FLOW TO THE HEATER CORE WARNING: The heater core inlet hose will become too hot to handle and may cause serious burns if the system is working correctly. Key in ON position. Run the engine until it reaches normal operation temperature. Select the FLOOR position on the control assembly. Set the temperature control to full WARM. Feel the heater core inlet hose to see if it is hot. Is the heater core inlet hose hot? Yes: GO to H4. No: REFER to «ENGINE COOLING - F150 PICKUP»(ref-206738) to check cooling system function.
H4 CHECK FOR A PLUGGED OR RESTRICTED HEATER CORE WARNING: The heater core outlet hose will become too hot to handle and may cause serious burns if the system is operating correctly. Feel the heater core outlet hose to see if it is hot. Is the heater core outlet hose hot? Yes: GO to «PINPOINT TEST D: INCORRECT/ERRATIC DIRECTION OF AIRFLOW FROM OUTLET(S)»(ref-206745-S42175074982005112600000) and diagnose for a blend door actuator. No: INSTALL a new heater core (18476). TEST the system for normal operation.

An open in circuit 441 (RD/YE), 348 (VT), 883 (PK/LB), 295 (LB/PK), 347 (BK/YE), 57 (BK), 391 (RD/YE), 321 (GY/WH) or 331 (PK/YE).
PCM.
(EATC systems) EATC module.
(EMTC systems) EMTC module.
A/C cycling switch.
A/C pressure cutoff switch.
A/C compressor clutch field coil.
A/C control relay.
A/C clutch air gap.

An open in circuit 331 (PK/YE).
A short to voltage in circuit 321 (GY/WH), 348 (VT) or 331 (PK/YE).
A short to ground in circuit 331 (PK/YE).
PCM.
(EATC systems) EATC module.
(Manual climate control systems) Manual climate control module.
A/C compressor clutch field coil.
A/C control relay.
A/C clutch air gap.

Scheme 147

Scheme 147: PINPOINT TEST J: THE AIR CONDITIONING (A/C) IS ALWAYS ON

Scheme 148

Scheme 149

Scheme 150

Scheme 151

Scheme 152

J1 CHECK A/C CLUTCH RELAY FAULT PID WITH THE A/C OFF Key in ON position. With the engine running, press the OFF manual override button on the EATC module or select the OFF position on the EMTC module. Enter the following diagnostic mode on the diagnostic tool: PCM A/C Clutch Relay Fault PID. Does the PCM A/C clutch relay fault PID read YES? Yes: REPAIR circuit 331 (PK/YE). TEST the system for normal operation. No: EATC systems, GO to J2. EMTC systems, GO to J3.
J2 CHECK A/C SWITCH PID WITH THE A/C OFF Enter the following diagnostic mode on the diagnostic tool: PCM A/C Switch PID. Does the PCM A/C switch PID read ON? Yes: INSTALL a new EATC module. TEST the system for normal operation. No: GO to J5.
J3 CHECK THE EMTC A/C SIGNAL WITH THE A/C OFF Key in OFF position. Disconnect: Instrument Cluster C2206. Key in ON position. Select the OFF position on the EMTC module. Measure the resistance between instrument cluster C2206-2, circuit 348 (VT) and ground. Is the resistance less than 5 ohms? Yes: GO to J4. No: GO to J5.
J4 CHECK CIRCUIT 348 (VT) FOR A SHORT TO GROUND Key in OFF position. Disconnect: EMTC Module C294a. Measure the resistance between instrument cluster C2206-2, circuit 348 (VT) and ground. Is the resistance greater than 10,000 ohms? Yes: INSTALL a new EMTC module. TEST the system for normal operation. No: REPAIR circuit 348 (VT) for a short to ground. TEST the system for normal operation.
J5 CHECK ACCS PID WITH THE A/C OFF Enter the following diagnostic mode on the diagnostic tool: PCM ACCS PID. Does the PCM ACCS PID read ON? Yes: For EATC systems, INSTALL a new PCM. TEST the system for normal operation. For manual climate control systems, GO to J6. No: GO to J7.
J6 CHECK CIRCUIT 348 (VT) FOR A SHORT TO VOLTAGE Key in OFF position. Disconnect: EMTC Module C294a. Disconnect: Instrument Cluster. Key in ON position. Measure the voltage between EMTC module C294a-3,circuit 348 (VT) and ground. Is the voltage greater than 10 volts? Yes: INSTALL a new PCM. TEST the system for normal operation. No: REPAIR circuit 348 (VT) for a short to voltage. TEST the system for normal operation.
J7 CHECK FOR VOLTAGE TO THE A/C COMPRESSOR CLUTCH FIELD COIL Key in OFF position. Disconnect: A/C Compressor Clutch Field Coil C1110. Key in ON position. Measure the voltage between A/C compressor clutch field coil C1110-1, circuit 321 (GY/WH) and ground. Is the voltage greater than 10 volts? Yes: GO to J8. No: GO to J9.
J8 CHECK CIRCUIT 321 (GY/WH) FOR A SHORT TO VOLTAGE Key in OFF position. Disconnect: A/C Control Relay. Key in ON position. Measure the voltage between A/C compressor clutch field coil C1110-1, circuit 321 (GY/WH) and ground. Is the voltage greater than 10 volts? Yes: REPAIR circuit 321 (GY/WH) for a short to voltage. TEST the system for normal operation. No: INSTALL a new A/C control relay. TEST the system for normal operation.
J9 CHECK THE A/C COMPRESSOR CLUTCH AIR GAP Key in OFF position. Measure the A/C compressor clutch air gap at three equally spaced locations between the clutch hub and the A/C compressor clutch pulley. Is the A/C compressor clutch air gap greater than 0.030 in (0.75 mm)? Yes: ADJUST the A/C compressor clutch gap. REFER to «AIR CONDITIONING (A/C) CLUTCH AIR GAP ADJUSTMENT»(ref-206745-S05103553432005112600000) . TEST the system for normal operation. No: INSTALL a new A/C compressor clutch field coil. TEST the system for normal operation.

An open in circuit 755 (BN/WH), 57 (BK), 399 (BN/YE), 461 (OG) or the relay coil and switch supply voltage circuit.
Blower motor.
Blower motor relay.

Scheme 153

Scheme 153: PINPOINT TEST K: THE BLOWER MOTOR IS INOPERATIVE - EMTC

Scheme 154

Scheme 155

Scheme 156

Scheme 157

Scheme 158

Scheme 159

Scheme 160

Scheme 161

K1 CHECK CIRCUIT 755 (BN/WH) FOR GROUND Disconnect: Blower Motor C2004. Turn the function selector switch to the vent position. Turn the blower motor switch to the HIGH position. Measure the resistance between A/C blower motor connector C2004-2, circuit 755 (BN/WH) and ground. Is the resistance less than 5 ohms? Yes: GO to K4. No: GO to K2.
K2 CHECK CIRCUIT 755 (BN/WH) FOR AN OPEN Disconnect: Blower Motor Switch C294b. Measure the resistance between blower motor switch C294b-2, circuit 755 (BN/WH) and blower motor C2004-2, circuit 755 (BN/WH). Is the resistance less than 5 ohms? Yes: GO to K3. No: REPAIR circuit 755 (BN/WH) for an open. TEST the system for normal operation.
K3 CHECK CIRCUIT 57 (BK) FOR AN OPEN Measure the resistance between blower motor switch C294b-1, circuit 57 (BK) and ground. Is the resistance less than 5 ohms? Yes: INSTALL a new blower motor switch. TEST the system for normal operation. No: REPAIR circuit 57 (BK) for an open. TEST the system for normal operation.
K4 CHECK A/C BLOWER MOTOR CIRCUIT 399 (BN/YE) FOR VOLTAGE Key in ON position. Measure the voltage between A/C blower motor connector C2004-1, circuit 399 (BN/YE) and ground. Is the voltage greater than 10 volts? Yes: INSTALL a new blower motor. TEST the system for normal operation. No: GO to K5.
K5 CHECK CIRCUIT 399 (BN/YE) FOR AN OPEN Key in OFF position. Disconnect: Blower Motor Relay. Measure the resistance between blower motor relay connector pin 87, circuit 399 (BN/YE) and blower motor C2004-1, circuit 399 (BN/YE). Is the resistance less than 5 ohms? Yes: GO to K6. No: REPAIR circuit 399 (BN/YE) for an open. TEST the system for normal operation.
K6 CHECK THE BLOWER MOTOR RELAY Connect: Blower Motor C2004. Key in ON position. Connect a fused jumper lead between blower motor relay socket pin 30 and pin 87, circuit 399 (BN/YE). Does the blower motor operate? Yes: GO to K7. No: REPAIR the relay power circuit. TEST the system for normal operation.
K7 CHECK THE RELAY COIL SUPPLY VOLTAGE Key in OFF position. Measure the voltage between blower motor relay socket pin 86 and ground. Is the voltage greater than 10 volts? Yes: GO to K8. No: REPAIR the circuit. TEST the system for normal operation.
K8 CHECK THE BLOWER MOTOR RELAY Key in ON position. Measure the voltage between blower motor relay socket pin 85, circuit 461 (OG) and socket pin 86. Is the voltage greater than 10 volts? Yes: INSTALL a new blower motor relay. TEST the system for normal operation. No: GO to K9.
K9 CHECK CIRCUIT 461 (OG) FOR AN OPEN Key in OFF position. Disconnect: EMTC module C294a. Measure the resistance between blower motor relay connector pin 85, circuit 461 (OG) and EMTC module C294a-23, circuit 461 (OG). Is the resistance less than 5 ohms? Yes: INSTALL a new EMTC module. TEST the system for normal operation. No: REPAIR circuit 461 (OG) for an open. TEST the system for normal operation.

An open in circuit 57 (BK), 755 (BN/WH), 751 (DB/WH) or 752 (YE/RD).
A short to ground in circuit 755 (BN/WH), 751 (DB/WH) or 752 (YE/RD).
A short together circuits 755 (BN/WH), 751 (DB/WH) or 752 (YE/RD).
Blower motor resistor.
Blower motor switch.

Scheme 162

Scheme 162: PINPOINT TEST L: THE BLOWER MOTOR DOES NOT OPERATE CORRECTLY - EMTC

Scheme 163

Scheme 164

Scheme 165

Scheme 166

Scheme 167

Scheme 168

Scheme 169

L1 CHECK THE BLOWER MOTOR OPERATION Key in ON position. Turn the function selector switch to the FLOOR position. Select all blower speed positions. Does the blower motor operate in any position? Yes: If the blower motor does not operate in HI, GO to L2. If the blower motor does not operate in MED-HI, GO to L3. If the blower motor does not operate in MED-LO, GO to L4. If the blower motor does not operate in LO, GO to L5. For all other symptoms, GO to L9. No: Go To «PINPOINT TEST K: THE BLOWER MOTOR IS INOPERATIVE - EMTC»(ref-206745-S19243838162005112600000) .
L2 CHECK CIRCUIT 755 (BN/WH) FOR AN OPEN Key in OFF position. Disconnect: Blower Motor Switch C294b. Disconnect: Blower Motor C2004. Measure the resistance between blower motor switch C294b-2, circuit 755 (BN/WH) and blower motor C2004-2, circuit 755 (BN/WH). Is the resistance less than 5 ohms? Yes: GO to L6. No: REPAIR circuit 755 (BN/WH) for an open. TEST the system for normal operation.
L3 CHECK CIRCUIT 751 (DB/WH) FOR AN OPEN Key in OFF position. Disconnect: Blower Motor Switch C294b. Disconnect: Blower Motor Resistor C2185. Measure the resistance between blower motor switch C294b-3, circuit 751 (DB/WH) and blower motor resistor C2185-3, circuit 751 (DB/WH). Is the resistance less than 5 ohms? Yes: GO to L6. No: REPAIR circuit 751 (DB/WH) for an open. TEST the system for normal operation.
L4 CHECK CIRCUIT 752 (YE/RD) FOR AN OPEN Key in OFF position. Disconnect: Blower Motor Switch C294b. Disconnect: Blower Motor Resistor C2185. Measure the resistance between blower motor switch C294b-4, circuit 752 (YE/RD) and blower motor resistor C2185-1, circuit 752 (YE/RD). Is the resistance less than 5 ohms? Yes: GO to L6. No: REPAIR circuit 752 (YE/RD) for an open. TEST the system for normal operation.
L5 CHECK BLOWER MOTOR RESISTOR GROUND CIRCUIT 57 (BK) FOR AN OPEN Measure the resistance between blower motor resistor C2185-4, circuit 57 (BK) and ground. Is the resistance less than 5 ohms? Yes: GO to L6. No: REPAIR circuit 57 (BK) for an open. TEST the system for normal operation.
L6 CHECK THE BLOWER MOTOR RESISTOR CIRCUIT 755 (BN/WH) FOR AN OPEN Connect: Blower Motor C2004. Measure the resistance between blower motor resistor C2185-2, circuit 755 (BN/WH) and blower motor C2004-2, circuit 755 (BN/WH). Is the resistance less than 5 ohms? Yes: GO to L7. No: REPAIR circuit 755 (BN/WH) for an open. TEST the system for normal operation.
L7 CHECK THE BLOWER MOTOR RESISTOR Carry out the «BLOWER MOTOR RESISTOR»(ref-206745-S34909597222005112600000) component test. Does the blower motor resistor test good? Yes: GO to L8. No: INSTALL a new blower motor resistor. TEST the system for normal operation.
L8 CHECK THE BLOWER MOTOR SWITCH CIRCUIT 57 (BK) FOR AN OPEN Measure the resistance between blower motor switch C294b-1, circuit 57 (BK) and ground. Is the resistance less than 5 ohms? Yes: INSTALL a new blower motor switch. TEST the system for normal operation. No: REPAIR circuit 57 (BK) for an open. TEST the system for normal operation.
L9 CHECK CIRCUITS 755 (BN/WH), 752 (YE/RD) AND 751 (DB/WH) FOR A SHORT TO GROUND Key in OFF position. Disconnect: Blower Motor C2004. Disconnect: Blower Motor Resistor C2185. Place the blower switch in the lowest setting. Measure the resistance between ground and blower motor resistor C2185, circuit: 752 (YE/RD) pin 1 755 (BN/WH) pin 2 751 (DB/WH) pin 3 Are the resistances less than 5 ohms? Yes: GO to L10. No: REPAIR the affected circuit. TEST the system for normal operation.
L10 CHECK THE BLOWER MOTOR CIRCUITS FOR SHORTS TOGETHER Measure the resistance between blower motor resistor C2185: pin 1, circuit 752 (YE/RD) and pin 2, circuit 755 (BN/WH). pin 1, circuit 752 (YE/RD) and pin 3, circuit 751 (DB/WH). pin 2, circuit 755 (BN/WH) and pin 3, circuit 751 (DB/WH). Are the resistances greater than 10,000 ohms? Yes: INSTALL a new blower motor switch. TEST the system for normal operation. No: REPAIR the affected circuits. TEST the system for normal operation.

An open in circuit 57 (BK), 755 (BN/WH), 399 (BN/YE) or 461 (OG).
A short to ground in circuit 269 (LB/OG).
A short to voltage in circuit 461 (OG).
Blower motor relay.
Blower motor control module.
EATC module.

Scheme 170

Scheme 170: PINPOINT TEST M: THE BLOWER MOTOR IS INOPERATIVE - EATC

Scheme 171

Scheme 172

Scheme 173

Scheme 174

Scheme 175

Scheme 176

Scheme 177

Scheme 178

Scheme 179

Scheme 180

Scheme 181

Scheme 182

M1 VERIFY THE BLOWER MOTOR OPERATION Key in ON position. Press the PANEL button on the EATC module. Adjust the blower motor setting to LO and then to HI. Is the blower motor inoperative in all settings? Yes: GO to M2. No: Go To «PINPOINT TEST N: THE BLOWER MOTOR DOES NOT OPERATE CORRECTLY - EATC»(ref-206745-S25725216122005112600000) .
M2 CHECK FOR VOLTAGE TO THE BLOWER MOTOR Key in OFF position. Disconnect: Blower Motor C2004. Key in ON position. Measure the voltage between blower motor C2004-1, circuit 399 (BN/YE) and ground. Is the voltage greater than 10 volts? Yes: GO to M3. No: GO to M9.
M3 CHECK FOR VOLTAGE TO THE BLOWER MOTOR CONTROLLER Key in OFF position. Disconnect: Blower Motor Speed Control C271. Key in ON position. Measure the voltage between blower motor speed control C271-4, circuit 399 (BN/YE) and ground. Is the voltage greater than 10 volts? Yes: GO to M4. No: REPAIR circuit 399 (BN/YE) for an open. TEST the system for normal operation.
M4 CHECK CIRCUIT 57 (BK) FOR AN OPEN Key in OFF position. Measure the resistance between blower motor speed control C271-2, circuit 57 (BK) and ground. Is the resistance less than 5 ohms? Yes: GO to M5. No: REPAIR circuit 57 (BK) for an open. TEST the system for normal operation.
M5 CHECK CIRCUIT 755 (BN/WH) FOR AN OPEN Measure the resistance between blower motor C2004-2, circuit 755 (BN/WH) and blower motor speed control C271-1, circuit 755 (BN/WH). Is the resistance less than 5 ohms? n Yes: GO to M6. No: REPAIR circuit 755 (BN/WH) for an open. TEST the system for normal operation.
M6 CHECK THE BLOWER MOTOR Connect: Blower Motor C2004. Connect a fused jumper lead between blower motor speed control C271-1, circuit 755 (BN/WH) and C271-2, circuit 57 (BK). Key in ON position. Does the blower motor operate? Yes: GO to M7. No: INSTALL a new blower motor. TEST the system for normal operation.
M7 CHECK CIRCUIT 269 (LB/OG) FOR A SHORT TO GROUND Key in OFF position. Remove the fused jumper lead from blower motor speed control C271. Disconnect: EATC Module C228b. Measure the resistance between blower motor speed control C271-3, circuit 269 (LB/OG) and ground. Is the resistance greater than 10,000 ohms? Yes: GO to M8. No: REPAIR circuit 269 (LB/OG). TEST the system for normal operation.
M8 CHECK CIRCUIT 269 (LB/OG) FOR AN OPEN Key in OFF position. Measure the resistance between blower motor speed control C271-3, circuit 269 (LB/OG) and EATC module C228b-18, circuit 269 (LB/OG). Is the resistance less than 5 ohms? Yes: INSTALL a new blower motor speed control. TEST the system for normal operation. If the blower motor is still inoperative, INSTALL a new EATC module. TEST the system for normal operation. No: REPAIR circuit 269 (LB/OG) for an open. TEST the system for normal operation.
M9 CHECK CIRCUIT 399 (BN/YE) FOR AN OPEN Key in OFF position. Disconnect: Blower Motor Relay. Measure the resistance between blower motor relay socket pin 87, circuit 399 (BN/YE) and blower motor C2004-1, circuit 399 (BN/YE). Is the resistance less than 5 ohms? Yes: GO to M10. No: REPAIR circuit 399 (BN/YE) for an open. TEST the system for normal operation.
M10 CHECK THE RELAY COIL SUPPLY VOLTAGE Measure the voltage between blower motor relay socket pin 86 and ground. Is the voltage greater than 10 volts? Yes: GO to M11. No: REPAIR the circuit for an open. TEST the system for normal operation.
M11 CHECK THE RELAY SWITCH POWER CIRCUIT FOR AN OPEN Measure the voltage between blower motor relay socket pin 30 and ground. Is the voltage greater than 10 volts? Yes: GO to M12. No: REPAIR the circuit for an open. TEST the system for normal operation.
M12 CHECK THE EATC MODULE OUTPUT Key in ON position. Measure the voltage between blower motor relay socket pin 86 and socket pin 85, circuit 461 (OG). Is the voltage greater than 10 volts? Yes: INSTALL a new blower motor relay. TEST the system for normal operation. No: GO to M13.
M13 CHECK CIRCUIT 461 (OG) FOR SHORT TO A VOLTAGE Key in OFF position. Disconnect: EATC Module C228b. Key in ON position. Measure the voltage between blower motor relay socket pin 85, circuit 461 (OG) and ground. Is voltage present? Yes: REPAIR circuit 461 (OG). TEST the system for normal operation. No: GO to M14.
M14 CHECK CIRCUIT 461 (OG) FOR AN OPEN Measure the resistance between EATC module C228a-23, circuit 461 (OG) and blower motor relay socket pin 85, circuit 461 (OG). Is the resistance less than 5 ohms? Yes: INSTALL a new EATC module. TEST the system for normal operation. No: REPAIR circuit 461 (OG) for an open. TEST the system for normal operation.

An open in circuit 269 (LB/OG).
A short to ground in circuit 755 (BN/WH) or circuit 461 (OG).
A short to voltage in circuit 269 (LB/OG) or circuit 399 (BN/YE).
Blower motor control module.
EATC module.

Scheme 183

Scheme 183: PINPOINT TEST N: THE BLOWER MOTOR DOES NOT OPERATE CORRECTLY - EATC

Scheme 184

Scheme 185

Scheme 186

Scheme 187

N1 VERIFY THE BLOWER MOTOR OPERATION Key in ON position. Press the PANEL button on the EATC module. Adjust the blower motor setting to LO and then to HI. Does the blower motor operate at any setting? Yes: If the blower motor operates always in HIGH, GO to N2. If the blower motor is always ON, GO to 5 . No: Go To «PINPOINT TEST M: THE BLOWER MOTOR IS INOPERATIVE - EATC»(ref-206745-S42868314392005112600000) .
N2 CHECK CIRCUIT 755 (BN/WH) FOR A SHORT TO GROUND Key in OFF position. Disconnect: Blower Motor Speed Control C271. Key in ON position. Does the blower motor operate? Yes: REPAIR circuit 755 (BN/WH) for a short to ground. TEST the system for normal operation. No: GO to N3.
N3 CHECK CIRCUIT 269 (LB/OG) FOR A SHORT TO VOLTAGE Key in OFF position. Disconnect: EATC Module C228b. Key in ON position. Measure the voltage between blower motor speed control C271-3, circuit 269 (LB/OG) and ground. Is voltage present? Yes: REPAIR circuit 269 (LB/OG) for a short to voltage. TEST the system for normal operation. No: GO to N4.
N4 CHECK CIRCUIT 269 (LB/OG) FOR AN OPEN Key in OFF position. Measure the resistance between blower motor speed control C271-3, circuit 269 (LB/OG) and EATC module C228b-18, circuit 269 (LB/OG). Is the resistance less than 5 ohms? Yes: INSTALL a new blower motor speed control. TEST the system for normal operation. No: REPAIR circuit 269 (LB/OG) for an open. TEST the system for normal operation.
N5 CHECK THE EATC MODULE OUTPUT Key in OFF position. Disconnect: Blower Motor Relay. Key in ON position. Press the EATC OFF button. Measure the voltage between blower motor relay socket pin 86 and socket pin 85, circuit 461 (OG). Is the voltage greater than 10 volts? Yes: GO to N6. No: GO to N7.
N6 CHECK CIRCUIT 461 (OG) FOR A SHORT TO GROUND Key in OFF position. Disconnect: EATC Module C228b. Measure the resistance between blower motor relay socket pin 85, circuit 461 (OG) and ground. Is the resistance greater than 10,000 ohms? Yes: INSTALL a new EATC module. TEST the system for normal operation. No: REPAIR circuit 461 (OG) for a short to ground. TEST the system for normal operation.
N7 CHECK CIRCUIT 755 (BN/WH) FOR A SHORT TO VOLTAGE Key in OFF position. Disconnect: Blower Motor C2004. Key in ON position. Measure the voltage between blower motor C2004-1, circuit 755 (BN/WH) and ground. Is the voltage greater than 10 volts? Yes: REPAIR circuit 755 (BN/WH) for a short to voltage. TEST the system for normal operation. No: INSTALL a new blower motor speed control. TEST the system for normal operation. If the blower motor still does not operate correctly, INSTALL a new EATC module. TEST the system for normal operation.

Scheme 188

Scheme 188: Blower Motor Resistor

Blower Motor Resistor Pins	Resistance
4 and 2	2.0-2.6 ohms
2 and 3	0.2-0.4 ohms
2 and 1	0.8-1.1 ohms

BLOWER MOTOR RESISTOR PINS RESISTANCE

In-Vehicle Temperature Sensor - EATC

Scheme 189

Temperature	Resistance
10-20°C (50-68°F)	37,000-58,000 ohms
20-30°C (68-86°F)	24,000-37,000 ohms
30-40°C (86-104°F)	16,000-24,000 ohms

TEMPERATURE RESISTANCE CHART

WARNING

Carbon monoxide is colorless, odorless and dangerous. If it is necessary to operate the engine with the vehicle in a closed area such as a garage, always use an exhaust collector to vent the exhaust gases outside the closed area.

Inspect for evidence of coolant leakage at the heater water hose to heater core attachments. A coolant leak in the heater water hose could follow the heater core tube to the heater core (18476) and appear as a leak in the heater core.
Check the integrity of the heater water hose clamps.