Signal Too Low
Signal too low
Checking the blower fan
- Ignition on.
Check that the blower fan functions by turning the blower fan knob to maximum fan speed.
Is the blower fan working?
Yes - Checking the wiring
No - Checking components and wiring
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Checking components and wiring
- Ignition off.
Caution! The blower fan motor power unit is very sensitive to short-circuits and excess current. Do not damage the power unit when taking readings.Take readings with the power unit connector disconnected when checking the wiring.
Check if the fuse for the climate control module (CCM) is defective. If the fuse is defective, check:
- the signal cable between the fuse and the power unit terminal #A2. Check for a short-circuit to ground
- the signal cable between the power unit terminal #B2 and the blower fan motor positive terminal. Check for a short-circuit to ground.
Check the control signal cable between control module terminal #A3 and power unit terminal #A1. Check for a short-circuit to supply voltage.
Check the diagnostic signal cable between control module terminal #A2 and power unit terminal #A3. Check for an open-circuit. Check for a short-circuit to ground.
Remedy as necessary.
Other information:
- To access or replace the control module, see Climate control module (CCM), replacing Service and Repair
- To access the control module or connect the breakout box, see Connecting the breakout box Connecting the Breakout Box, Climate Control Module (CCM)
- To access or replace the power unit, see Blower fan motor / power unit, replacing Blower Fan Motor/Power Unit (Blower Motor Resistor), Replacing
- With the ignition on and the power unit connector disconnected, the voltage between power unit connector terminal #A2 (control module side) and ground must be approximately 13.5 V
- For other values, see Signal specification Pinout Values and Diagnostic Parameters
- Checking wiring and terminals Checking Wiring And Terminals.
Continue - Verification
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Checking the wiring
- Ignition off.
Caution! The blower fan motor power unit is very sensitive to short-circuits and excess current. Do not damage the power unit when taking readings.Take readings with the power unit connector disconnected when checking wiring.
Check the signal cable between the fuse and the power unit terminal #A2. Check for an intermittent short-circuit to ground.
Check the signal cable between power unit terminal #B2 and blower fan motor positive terminal. Check for an intermittent short-circuit to ground.
Check the control signal cable between control module terminal #A3 and power unit terminal #A1. Check for an intermittent short-circuit to supply voltage.
Check the diagnostic signal cable between control module terminal #A2 and power unit terminal #A3. Check for an intermittent open-circuit. Check for a short-circuit to ground.
Note! If the battery voltage has been interrupted, the blower fan speed must be calibrated. First turn the blower fan speed control to maximum speed and then to minimum speed.
Remedy as necessary.
Other information:
- To access or replace the control module, see Climate control module (CCM), replacing Service and Repair
- To connect the breakout box, see Connecting the breakout box Connecting the Breakout Box, Climate Control Module (CCM)
- To access or replace the power unit, see Blower fan motor / power unit, replacing Blower Fan Motor/Power Unit (Blower Motor Resistor), Replacing
- With the ignition on and the power unit connector disconnected, the voltage between power unit connector terminal #A2 (control module side) and ground must be approximately 13.5 V
- For other values, see Signal specification Pinout Values and Diagnostic Parameters
- Checking wiring and terminals Checking Wiring And Terminals.
Continue - Fault-tracing information
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Verification
Verification
Verification
Hint: After the repair it is necessary to check that the fault has been rectified.
- Ignition off.
- Connect the connectors, install the components, etc.
- Ignition on.
- Read the diagnostic trouble codes.
If the status of the diagnostic trouble code has changed to an intermittent fault this indicates that the fault has been rectified.
Has the status of the diagnostic trouble code changed?
Yes - VERIFIED
No - VERIFICATION FAILED
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VERIFIED - Fault Found
VERIFICATION FAILED - Fault-tracing information
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Fault-tracing information
Information
Fault-tracing information
The fault should have been detected and remedied. As this is not the case fault-tracing has failed.
Exit fault-tracing for this diagnostic trouble code (DTC) or make another attempt.
Do you want to exit fault-tracing?
Yes - FAULT-TRACING FAILED
No - Attempt New Test
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FAULT-TRACING FAILED - No Fault Found
Attempt New Test - Checking the blower fan
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Fault-tracing information
Information
Fault-tracing information
If the fault is intermittent, do not verify fault-tracing if the fault does not recur.
It is possible to view the information again, or leave fault-tracing for this diagnostic trouble code (DTC).
Do you want to view the information again?
Yes - Attempt New Test
No - Fault Found
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Attempt New Test - Checking the blower fan
FAULT FOUND - DONE
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