Mazda CX-9 Grand Touring 2009 Manual page 1394

Pin discoloration (blackness)
If the #3 terminal measures other than B+ , inspect the following:
Open or short circuit in wiring harness
Harness/pin crimp is loose or disconnected.
Thermistor type (IAT sensor & CHT sensor)
Fig. 15: Thermistor Resistance Type (IAT Sensor & CHT Sensor)
Courtesy of MAZDA MOTORS CORP.
Input signal system inspection for thermistor type
1. When an irregular signal is detected, measure the #1 PCM terminal voltage.
If the #1 terminal voltage and the M-MDS monitor voltage are the same, proceed to the next step.
If there is a difference of 0.5 V or more , inspect the following points concerning the PCM
connector:
Female terminal opening loose
Coupler (pin holder) damage
Pin discoloration (blackness)
Harness/pin crimp is loose or disconnected.
2. Measure the #2 sensor terminal voltage.
If there is a 0.5 V or more difference between the sensor and the M-MDS voltages, inspect the
wiring harness for open or short circuits.
If the sensor and the M-MDS voltages are the same, inspect the following points concerning the
sensor connector:
Female terminal opening is loose.
Coupler (pin holder) damage
Pin discoloration (blackness)
Harness/pin crimp is loose or disconnected.
If there are no problems, proceed to next investigation below.
GND system inspection for thermistor type
Confirm that terminal sensor #3 is at 0 V.
2008 Mazda CX-9 Grand Touring
2008 ENGINE Symptom Troubleshooting (MZI-3.7) - Mazda CX-9