Chrysler Town, Dodge Caravan. Manual — part 756
Symptom:
*FRONT BLOWER MOTOR INOPERATIVE
POSSIBLE CAUSES
FRONT CONTROL MODULE (FCM) DTC(S) PRESENT
IPM FUSE #10
FUSED FRONT BLOWER MOTOR RELAY OUTPUT CIRCUIT SHORTED TO GROUND
BLOWER MOTOR SHORTED TO GROUND
FRONT BLOWER POWER MODULE SHORTRD TO GROUND
GROUND CIRCUIT OPEN
BLOWER MOTOR CONTROL CIRCUIT SHORTED TO VOLTAGE
BLOWER MOTOR CONTROL CIRCUIT OPEN
FRONT BLOWER POWER MODULE OPEN
AUTOMATIC TEMPERATURE CONTROL MODULE OPEN
CHECK BLOWER MOTOR OPERATION
FRONT BLOWER POWER MODULE OPEN
IPM - OPEN CIRCUIT
IPM - OPEN CIRCUIT
FRONT BLOWER MOTOR RELAY
IPM - OPEN CIRCUIT
FUSED FRONT BLOWER MOTOR RELAY OUTPUT CIRCUIT OPEN
TEST
ACTION
APPLICABILITY
1
With the DRBIII
t in FCM, read the active DTCs.
Are any active FCM DTCs present?
All
Yes
→ For FCM DTCs related to the blower relay circuits, refer to the
Heating & A/C catagory. For all other FCM DTCs, refer to the
symptom list in the related catagory.
With the DRBIII
t, reset the ATC after repair is complete.
Perform BODY VERIFICATION TEST - VER 1.
No
→ Go To 2
2
Turn the ignition off.
Remove and inspect Intelligent Power Module (IPM) Fuse #10.
Is the fuse open?
All
Yes
→ Go To 3
No
→ Go To 6
260
AUTOMATIC TEMPERATURE CONTROL
TEST
ACTION
APPLICABILITY
3
Replace IPM Fuse #10.
Turn the ignition on.
Operate the blower motor in all speeds.
Start the engine and operate the ATC system in all modes and speeds.
Does the blower motor operate properly without blowing the fuse?
All
Yes
→ Refer to the wiring diagrams located in the service information to
help isolate a possible intermittent short to ground condition.
With the DRBIII
t, reset the ATC after repair is complete.
Perform BODY VERIFICATION TEST - VER 1.
No
→ Go To 4
4
Turn the ignition off.
Disconnect the Front Blower Power Module C1 harness connector.
Measure the resistance between ground and the Fused Front Blower Motor Relay
Output circuit.
Is the resistance below 10K ohms?
All
Yes
→ Repair the Fused Front Blower Motor Relay Output circuit for a
short to ground. Replace IPM Fuse #10.
With the DRBIII
t, reset the ATC after repair is complete.
Perform BODY VERIFICATION TEST - VER 1.
No
→ Go To 5
5
Turn the ignition off.
Replace IPM Fuse #10.
Disconnect the Front Blower Power Module C1 harness connector.
Disconnect the Front Blower Power Module C2 harness connector.
Connect a jumper wire between the Fused Front Blower Motor Relay Output circuit
in the Front Blower Power Module C1 harness connector and the DB wire in the
Front Blower Power Module C2 harness connector.
Connect a jumper wire between the Ground circuit in the Front Blower Power
Module C1 harness connector and the DB/YL wire in the Front Blower Power Module
C2 harness connector.
Turn the ignition on.
Does the Blower Motor operate at full speed without blowing the fuse?
All
Yes
→ Replace the Front Blower Power Module in accordance with the
Service Information. Replace IPM Fuse #10.
With the DRBIII
t, reset the ATC after repair is complete.
Perform BODY VERIFICATION TEST - VER 1.
No
→ Replace the Blower Motor in accordance with the Service Infor-
mation. Replace IPM Fuse #10.
With the DRBIII
t, reset the ATC after repair is complete.
Perform BODY VERIFICATION TEST - VER 1.
6
Ensure IPM Fuse #10 is installed.
Disconnect the Front Blower Power Module C1 harness connector.
Turn the ignition on.
NOTE: The test light must illuminate brightly. Compare the brightness to
that of a direct connection to the battery.
Using a 12-volt test light connected to ground, back probe the Fused Front Blower
Motor Relay Output circuit in the Front Blower Power Module C1 harness connector.
Does the test light illuminate brightly?
All
Yes
→ Go To 7
No
→ Go To 13
261
AUTOMATIC TEMPERATURE CONTROL
*FRONT BLOWER MOTOR INOPERATIVE —
Continued
TEST
ACTION
APPLICABILITY
7
Turn the ignition off.
Disconnect the Front Blower Power Module C1 harness connector.
Measure the resistance between ground and the Ground circuit.
Is the resistance below 5.0 ohms?
All
Yes
→ Go To 8
No
→ Repair the Ground circuit for an open.
With the DRBIII
t, reset the ATC after repair is complete.
Perform BODY VERIFICATION TEST - VER 1.
8
Turn the ignition off.
Disconnect the Front Blower Power Module C1 harness connector.
Disconnect the Automatic Temperature Control Module C2 harness connector.
Turn the ignition on.
Measure the voltage of the Blower Motor Control circuit.
Is there any voltage present?
All
Yes
→ Repair the Blower Motor Control circuit for a short to voltage.
With the DRBIII
t, reset the ATC after repair is complete.
Perform BODY VERIFICATION TEST - VER 1.
No
→ Go To 9
9
Turn the ignition off.
Disconnect the Front Blower Power Module C1 harness connector.
Disconnect the Automatic Temperature Control Module C2 harness connector.
Measure the resistance of the Blower Motor Control circuit between the Front Blower
Power Module C1 harness connector and the Automatic Temperature Control Module
C2 harness connector.
Is the resistance below 5.0 ohms?
All
Yes
→ Go To 10
No
→ Repair the Blower Motor Control circuit for an open.
With the DRBIII
t, reset the ATC after repair is complete.
Perform BODY VERIFICATION TEST - VER 1.
10
Turn the ignition off.
Make sure that the Front Blower Power Module C1 harness connector is connected
to the Front Blower Power Module.
Make sure that the Automatic Temperature Control Module C2 harness connector is
connected to the Automatic Temperature Control Module.
Start the engine.
Press the ATC Power Switch on.
Set the blower switch to the LO speed position.
While back probing, measure the voltage of the Blower Motor Control circuit in the
Automatic Temperature Control Module C2 harness connector.
Is the voltage above 10.0 volts?
All
Yes
→ Go To 11
No
→ Replace the Front Blower Power Module in accordance with the
Service Information.
With the DRBIII
t, reset the ATC after repair is complete.
Perform BODY VERIFICATION TEST - VER 1.
262
AUTOMATIC TEMPERATURE CONTROL
*FRONT BLOWER MOTOR INOPERATIVE —
Continued
TEST
ACTION
APPLICABILITY
11
Turn the ignition off.
Reconnect all previously disconnected components.
Connect the DRBIII
t X10 Scope Probe CH7061 to Channel 1 on the DRBIIIt.
Select the following from the DRBIII
t 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
t 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
t display the voltage range and duty cycle as described above?
All
Yes
→ Go To 12
No
→ Replace the Automatic Temperature Control Module in accor-
dance with the Service Information.
With the DRBIII
t, reset the ATC after repair is complete.
Perform BODY VERIFICATION TEST - VER 1.
263
AUTOMATIC TEMPERATURE CONTROL
*FRONT BLOWER MOTOR INOPERATIVE —
Continued
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