Chrysler Town and Country 2003 Owner's Manual page 287

*FRONT BLOWER MOTOR INOPERATIVE —
TEST
11 Turn the ignition off.
Reconnect all previously disconnected components.
Connect the DRBIII X10 Scope Probe CH7061 to Channel 1 on the DRBIII .
Select the following from the DRBIII menu: PEP Module Tools; Lab Scope; Live
Data; and Lab Scope.
Press F2 and then press Enter.
Using the left/right arrow keys, set the time to 10ms/Div.
Press F2.
Using the up/down arrow keys, set the voltage range to +20.0v.
Press Enter to move the cursor to Probe.
Using the up/down arrow keys, set the Probe to X10.
Press F2.
Start the engine.
Press the ATC Power switch on.
Using the X10 Scope Probe, back probe the Blower Motor Control circuit in the Front
Blower Power Module C1 harness connector.
NOTE: The Blower Power Module provides a 10.0 volt signal to the ATC
Module over the Blower Motor Control circuit. The ATC Module provides a
variable duty cycle ground to the 10.0 volt signal based on input from the
blower control switch.
NOTE: When the blower control switch is set to LO speed, the ATC Module
provides a short duty cycle (less time grounding the signal voltage).
NOTE: As higher blower speeds are requested, the ATC Module increases
the duty cycle (more time grounding the signal voltage).
NOTE: When the blower control switch reaches HI speed, the duty cycle
increases to where the signal pattern is almost a flat line (with brief voltage
spikes).
Set the blower switch to LO speed then slowly move it to HI speed while observing
the DRBIII display.
The voltage on the scope patten should cycle from approximately 2.0 volts (duty cycle
on) to 10.0 volts (duty cycle off) for all blower speeds.
The duty cycle pattern should change smoothly as the blower switch is turned from
LO to HI.
The duty cycle on time should change from approximately 8 ms at LO speed, to 15 ms
at medium speed, and to 25 ms at HI speed.
Does the DRBIII display the voltage range and duty cycle as described above?
Yes → Go To 12
→ Replace the Automatic Temperature Control Module in accor-
No
AUTOMATIC TEMPERATURE CONTROL
ACTION
dance with the Service Information.
With the DRBIII , reset the ATC after repair is complete.
Perform BODY VERIFICATION TEST - VER 1.
Continued
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APPLICABILITY
All