Without A/C

Circuit Description
Ignition voltage is supplied directly to the cooling fan relay coil. The powertrain control module (PCM)/engine control module (ECM) controls the relay by grounding the control circuit via an internal switch called a driver. The primary function of the driver is to supply the ground for the component being controlled. Each driver has a fault line which is monitored by the PCM/ECM. When the PCM/ECM is commanding a component ON, the voltage of the control circuit should be low (near 0 volts). When the PCM/ECM is commanding the control circuit to a component OFF, the voltage potential of the circuit should be high (near battery voltage). If the fault detection circuit senses a voltage other than what is expected, the fault line status will change causing the DTC to set.

The relay is used to control the high current flow to the cooling fan motors. This allows the PCM/ECM driver to only have to handle the relatively low current used by the relay.

Conditions for Setting the DTC
- Ignition ON.
- Ignition voltage is greater than 10 volts.
- Engine run time is greater than 5 seconds.

Action Taken When the DTC Sets
- The PCM/ECM will not illuminate the Malfunction Indicator Lamp (MIL).
- The PCM/ECM will record operating conditions at the time the diagnostic fails. This information will be stored in the Freeze Frame and/or Failure Records.
- A history DTC is stored.

Conditions for Clearing the MIL/DTC
- A history DTC will clear after forty consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
- PCM/ECM battery voltage is interrupted.
- DTC(s) can be cleared by using the scan tool.

Diagnostic Aids
Using Freeze Frame and/or Failure Records data may aid in locating an intermittent condition. If the DTC cannot be duplicated, the information included in the Freeze Frame and/or Failure Records data can be useful in determining how many miles since the DTC set. The Fail Counter and Pass Counter can also be used to determine how many ignition cycles the diagnostic reported a pass and/or fail. Operate the vehicle within the same freeze frame conditions (rpm, load, vehicle speed, temperature, etc.) that are noted. This will isolate when the DTC failed.

Steps 1 - 4:

Steps 5 - 15:

Test Description
The number(s) below refer to step(s) on the diagnostic table.
1. The On-Board Diagnostic (OBD II) System Check prompts the technician to complete some basic checks and store the freeze frame and failure records data on the scan tool if applicable. This creates an electronic copy of the data taken when the malfunction occurred. The information is then stored on the scan tool for later reference.
2. Listen for an audible click when the relay operates. Be sure that both the ON and the OFF states are commanded. Repeat the commands as necessary.
3. This check can detect a partially shorted coil which would cause excessive current flow. Leaving the circuit energized for 2 minutes allows the coil to warm up. When warm, the coil may open or short.
5. It is important to identify and test the relay coil terminals to avoid improper diagnosis.
13. If no trouble is found in the control circuit or the connection at the PCM/ECM, the PCM/ECM may be faulty. However, this is extremely unlikely. The replacement PCM/ECM must be reprogrammed. Refer to the latest Techline procedure for PCM/ECM reprogramming.