Diagnostic Procedure
WARNING: This page is about a different car, the 2005 Dodge Stratus and 2005 Chrysler Sebring. However, it is still accessible from the selected car via links, so may be relevant.
DIAGNOSTIC PROCEDURE - BLOWER RUNS AT ONLY ONE SPEED - ATC
| TEST | ACTION | APPLICABILITY |
|---|---|---|
| 1 | Turn the ignition on. With the DRBIII®, record and erase Body Computer DTC's. Cycle the ignition switch. With the DRBIII®, read the Body Computer DTCs. Does the DRBIII® display any DTCs? Yes --> Refer to the appropriate category for the related symptom(s). Perform BODY VERIFICATION TEST - VER 1 . No --> Go To 2 |
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| 2 | Turn the ignition on. With the DRBIII® in Automatic Temperature Control, Monitor Display, PCI Bus Info ATC, look for Fan Req To BCM. Does the DRB display: Fan Req To BCM: Yes? Yes --> Go To 3 No --> Replace the Automatic Temperature Control in accordance with the Service Information. Perform BODY VERIFICATION TEST - VER 1 . |
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| 3 | Turn the ignition off. Disconnect the Blower Power Module C1 harness connector. Disconnect the Body Control Module C1 harness connector. Measure the resistance between ground and the Blower Motor Control circuit. Is the resistance below 10K ohms? Yes --> Repair the Blower Motor Control circuit for a short to ground. Perform BODY VERIFICATION TEST - VER 1 . No --> Go To 4 |
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| 4 | Turn the ignition off. Reconnect all previously disconnected components. Connect the DRBIII® Scope Input Cable CH7058, Cable-To-Probe Adapter CH7062, and the Red (+) and Black (-) X1 Test Leads CH7030 to the DRBIII®. Select the following from the DRBIII® menu: PEP Module Tools; Lab Scope; Live Data; and Lab Scope. Set the time to 0.4ms/Div. Set the voltage range to +20.0v. Set the Offset to 4.00v. Set the Probe to X1. Start the engine. Turn Automatic Temperature Control on. Using the Red (+) X1 Test Lead, back probe the Blower Motor Control circuit in the Blower Power Module C1 harness connector. Connect the Black (-) X1 Test Lead to ground.
NOTE:
Over the Blower Motor Control circuit, the Blower Power Module provides a battery supply voltage signal to the Body Control Module (BCM) while the BCM provides a variable duty cycle ground based on input from the blower control switch.
NOTE:
When the blower control switch is set to Lo speed, the BCM provides a short duty cycle (less time grounding the signal). As higher blower speeds are requested, the BCM increases the duty cycle (more time grounding the signal).
NOTE:
When the blower control switch is set to High speed, the duty cycle increases to where the signal pattern is a flat line on ground. Set the blower control to LO speed and then slowly turn it to HI speed while observing the DRBIII® display. The duty cycle pattern should change smoothly as the blower switch is turned from Lo to High. The high part of the cycle will decrease as the blower speed increases. Does the DRBIII® display the signal as described above? Yes --> Replace the Blower Power Module in accordance with the Service Information. Perform BODY VERIFICATION TEST - VER 1 . No --> Replace and program the Body Control Module in accordance with the Service Information. Perform BODY VERIFICATION TEST - VER 1 . |
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