For 1990-2009 cars

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
Important: A short to ground will cause an open fuse. Before performing this diagnostic procedure, inspect the fuses for an open.
1 | Did you perform the HVAC Blower Controls System Check? | -- | Go to Step 2 | Go to HVAC Blower Controls System Check
2 | Exchange the blower motor relay with a known good relay from the underhood wiring harness junction block. Does the blower motor operate? | -- | Go to Step 3 | Go to Step 4
3 | Replace the faulty relay. Is the repair complete? | -- | Go to HVAC Blower Controls System Check | --
4 |

1. Turn the ignition switch to the ON position.
2. Turn the blower switch to HIGH.
3. Use the J 39200 Digital Multimeter (DMM) in order to backprobe the underhood wiring harness junction block connector C3.
4. Measure the voltage between terminal D9 and ground.

Does the voltage measured equal the specified value?

B+

Go to Step 7

Go to Step 5

5 |

1. Use the J 39200 DMM in order to backprobe the heater A/C control assembly connector C1.
2. Measure the voltage between terminal C and ground.

Does the voltage measured equal the specified value?

B+

Go to Step 8

Go to Step 6

6 | Replace the heater A/C control assembly. Is the repair complete? | -- | Go to HVAC Blower Controls System Check | --
7 | Using a test lamp, backprobe the underhood wiring harness junction block connector C3 between terminal D9 and terminal A10. Does the test lamp light? | -- | Go to Step 9 | Go to Step 10
8 | Repair the open in CKT 52 between the heater A/C control assembly and the underhood wiring harness junction block. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to HVAC Blower Controls System Check | --
9 | Replace the underhood wiring harness junction block. Refer to Relay/Fuse Center Replacement in Wiring Systems. Is the repair complete? | -- | Go to HVAC Blower Controls System Check | --
10 | Repair the open in CKT 150 between the underhood wiring harness junction block and ground splice pack G201. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to HVAC Blower Controls System Check | --