Pinpoint Test N: The Blower Motor is Inoperative
Climate Control System
Pinpoint Test N: The Blower Motor is Inoperative
Refer to Wiring Diagram Set 54, Manual Climate Control System for schematic and connector information Electrical Diagrams.
Normal Operation
The blower motor relay coil and relay switch contacts receive voltage. The blower motor relay is energized when the coil receives ground from the HVAC module, if the HVAC power is on. When the relay coil is energized, voltage is delivered to the blower motor. Ground for the blower motor is provided from the blower resistor or the blower switch (HI). The blower resistor is grounded through the blower motor switch. The blower motor switch is grounded. The blower motor switch is part of the HVAC module and can not be replaced separately.
- DTC 51 (Blower Relay Driver Circuit/Performance)- This DTC sets when any of the following occur:
- The module senses ground on the relay coil ground circuit when the relay is not grounded by the HVAC module, indicating a short directly to ground.
- The module senses voltage on the relay coil ground circuit when the relay is grounded by the HVAC module, indicating a short directly to voltage.
- The module senses no voltage on the relay coil ground circuit when the relay is not grounded by the HVAC module, indicating an open.
This pinpoint test is intended to diagnose the following:
- Fuse
- Wiring, terminals or connectors
- Blower motor
- Blower motor relay
- HVAC module
PINPOINT TEST N : THE BLOWER MOTOR IS INOPERATIVE
N1 CHECK THE HVAC MODULE FOR DTCs
- Ignition ON.
- CARRY OUT the HVAC module self-test.
- Check for HVAC DTCs retrieved during the self-test.
Is DTC 51 present?
Yes
GO to N2.
No
GO to N6.
N2 CHECK THE BLOWER MOTOR RELAY COIL SUPPLY VOLTAGE
- Ignition OFF.
- Disconnect: Blower Motor Relay.
- Ignition ON.
- Measure the voltage between blower motor relay socket pin 1, circuit CBP21 (BU/GY) and ground.
Is the voltage greater than 10 volts?
Yes
GO to N3.
No
REPAIR circuit CBP21 (BU/GY) for an open. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
N3 CHECK THE BLOWER MOTOR RELAY COIL
NOTICE: The following step uses a test light to simulate normal circuit loads. Use only the test light recommended in the Special Tools table at the beginning or equivalent. To avoid connector terminal damage, use the Flex Probe Kit for the test light probe connection to the vehicle. Do not use the test light probe directly on any connector.
- Select PANEL on the HVAC controls.
- Connect a 12-volt test light between blower motor relay socket pin 1, circuit CBP21 (BU/GY) and blower motor relay socket pin 2, circuit CH123 (VT/GN).
Does the test light illuminate?
Yes
INSTALL a new blower motor relay. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
No
GO to N4.
N4 CHECK THE BLOWER MOTOR RELAY COIL GROUND CIRCUIT FOR A SHORT TO VOLTAGE
- Ignition OFF.
- Disconnect: HVAC Module C228A.
- Ignition ON.
- Measure the voltage between blower motor relay socket pin 2, circuit CH123 (VT/GN) and ground.
Is any voltage present?
Yes
REPAIR circuit CH123 (VT/GN) for a short to voltage. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
No
GO to N5.
N5 CHECK THE BLOWER MOTOR RELAY COIL GROUND CIRCUIT FOR AN OPEN
- Ignition OFF.
- Measure the resistance between blower motor relay socket pin 2, circuit CH123 (VT/GN) and HVAC module C228A-3, circuit CH123 (VT/GN), harness side.
Is the resistance less than 5 ohms?
Yes
GO to N12.
No
REPAIR circuit CH123 (VT/GN) for an open. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
N6 CHECK THE BLOWER MOTOR RELAY SWITCH CONTACTS SUPPLY VOLTAGE
- Ignition OFF.
- Disconnect: Blower Motor Relay.
- Ignition ON.
- Measure the voltage between blower motor relay socket pin 3, circuit SBB04 (GN/RD) and ground.
Is the voltage greater than 10 volts?
Yes
GO to N7.
No
VERIFY Battery Junction Box (BJB) fuse 4 (40A) is OK. If OK, REPAIR circuit SBB04 (GN/RD) for an open. TEST the system for normal operation. If not OK, REFER to the Wiring Diagrams to identify the possible causes of the circuit short Electrical Diagrams.
N7 CHECK THE BLOWER MOTOR RELAY
- Select the highest blower motor speed on HVAC controls.
- Connect a fused jumper lead between blower motor relay socket pin 3, circuit SBB04 (GN/RD) and blower motor relay socket pin 5, circuit CH402 (YE/GN).
Does the blower motor operate?
Yes
INSTALL a new blower motor relay. TEST the system for normal operation.
No
GO to N8.
N8 CHECK THE BLOWER MOTOR GROUND CIRCUIT
- Ignition OFF.
- Disconnect: Blower Motor C2004.
- Turn the blower motor switch to the HI position.
- Measure the resistance between blower motor connector C2004-2, circuit CH430 (VT/OG), harness side and ground.
Is the resistance less than 5 ohms?
Yes
GO to N9.
No
GO to N10.
N9 CHECK THE BLOWER MOTOR VOLTAGE CIRCUIT FOR AN OPEN
- Measure the resistance between blower motor relay socket pin 5, circuit CH402 (YE/GN) and blower motor C2004-1, circuit CH402 (YE/GN), harness side.
Is the resistance less than 5 ohms?
Yes
INSTALL a new blower motor. TEST the system for normal operation.
No
REPAIR circuit CH402 (YE/GN) for an open. TEST the system for normal operation.
N10 CHECK THE BLOWER MOTOR GROUND CIRCUIT FOR AN OPEN
- Disconnect: HVAC Module C228B.
- Measure the resistance between HVAC module C228B-6, circuit CH430 (VT/OG), harness side and blower motor C2004-2, circuit CH430 (VT/OG), harness side.
Is the resistance less than 5 ohms?
Yes
GO to N11.
No
REPAIR circuit CH430 (VT/OG) for an open. TEST the system for normal operation.
N11 CHECK THE BLOWER MOTOR SWITCH GROUND CIRCUIT FOR AN OPEN
- Measure the resistance between HVAC module C228B-3, circuit GD115 (BK/GY), harness side and ground.
Is the resistance less than 5 ohms?
Yes
GO to N12.
No
REPAIR circuit GD115 (BK/GY) for an open. TEST the system for normal operation.
N12 CHECK THE HVAC MODULE CONNECTION
- Disconnect all the HVAC module connectors.
- Inspect the HVAC module connectors for:
- corrosion.
- pushed-out terminals.
- damaged terminals.
- Connect and correctly seat all the HVAC module connectors.
- Operate the system and verify the concern is still present.
Is the concern still present?
Yes
INSTALL a new HVAC module. TEST the system for normal operation.
No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.