PT Turbo Cooling Fan Operation
The 2003 Chrysler PT Cruiser Turbo Cooling Fan System is rather unique in operation and function – very much a system that is on an island by itself.
The system components are: powertrain control module (PCM) and the cooling fan assembly with integrated electronic cooling fan relay.
The PCM has full control when the cooling fan comes on and at what speed it chooses to operate the fan. This is a type of fan system that can have variable speeds. This is not an on/off type of cooling fan system. Testing this system is a bit challenging because the service information may seem a little deceiving.
A few areas to focus on when diagnosing a fan that does not operate: Testing should be done at the fan motor assembly connector. Everything on the fan side of this connector is serviced as one assembly so there is no need to try diagnosing any further than to that level. In other words, the relay and fan are not serviced separately; they are serviced as one complete assembly. The vehicle harness side of the connector and the pins of this connector are where all of the testing can be done. Here is the rundown of each pin and its function:
So what testing can be done if the fan never operates? All of the battery voltage and ground tests listed above should be performed first. That leaves the control circuit to the PCM. This is the challenging circuit. If the wire from Pin 4 of the fan connector is separated or removed from the connector, the fan should run at high speed. The other three wires need to remain intact as normal for this test to work. This is the default operation of this fan system. If the fan does not run, the fan assembly has failed.
If the fan does run at high speed, testing should be performed on the fan control circuit. Specifically, try running the cooling fan actuator test using a compatible scan tool. This test commands the PCM to control the fan. On this fan system, the more “ground time” this circuit has when connected, normally the slower the fan will run. The less ground time from the PCM, the faster the fan runs. That may be exactly opposite of what you’re used to. If you have any questions, just give us a call.
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