Intake Air Temperature (Iat) Sensor/Engine Coolant Temperature (Ect) Sensor - Mazda B-Series 1997 Workshop Manual

ON-BOARD DIAGNOSIS SYSTEM
p I
PO112
I
PO113
1
P1112: INTAKE AIR TEMPERATURE (IAT) SENSOR
PO117
1
PO118
1
PO125
I
PI116
1
P1117: ENGINE COOLANT TEMPERATURE (ECT)
Diagnostic trouble code
No. P0112, P0113,
PO1 17, PO1 18, PO1 25,
P1112, P1116, PI117
Symptom
SENSOR
-
Input from IAT or ECT sensor is below 0.2 volt or above 4.6 volts or intermittent when
ignition is turned on.
Insufficient coolant temperature for stable operation or to enter closed loop fuel control
I
(DTC PO1
25).
ACTION
For DTC P1116:
Go to next step.
For DTC PO113 or P0118:
Go to step 6.
For DTC PO112 or POllX:
Go to step 9.
For RetrieveIClear Continuous DTC P0112,
P0113, P0117, P0118, PI112 or P1117:
Go to step 12.
For DTC P0125:
Go to step 14.
For symptom of cooling system concern:
Do not service DTC P1116. Service next DTC. If
no other DTCs exist, return to Diagnostic Index.
All others:
Go to next step.
STEP
/
INSPECTION
Key OFF.
Inspect for damaged or pushed out pins, corrosion, loose
wires at IAT, ECT or PCM connector.
Repair or replace if necessaly.
Follow direction
in
Action.
-
Warm up engine at normal operating temperature.
I
No Starts: Go to step
4.
'
Vehicle Stalls: Go to Diagnostic Index.
Check that upper radiator hose
IS
hot and pressurized.
Rerun KOER self test.
Is DTC PI1 16 present?
Yes
Engine was not at closed loop operating
conditions. Repair any other DTCs as
necessaw.
3
1
Key OFF.
Disconnect throttle ~osition ITP) sensor connector.
Go to next step.
.
,
Key ON, engine off.'
Measure voltage between VREF and SIG RTN circuit at TP
sensor connector.
Is voltage between 4.0 and 6.0 volts?
No Go to pinpoint test ''VREIZ."
Yes
For ECT sensor with a No Start:
Do not service DTC PI116 at this time. Return to
Diagnostic Index.
All others:
Go to next step.
- -
No Replace ECT sensor.
Go to step 15.
Key OFF.
Disconnect ECT sensor connector.
Is resistance of sensor within specification?
page FT-186
Note: Verify that engine is at operating temperature
before taking ECT readings.
Key OFF.
Leave ECT sensor connector disconnected.
Run engine for two minutes at 2,000 rpm.
Is resistance of sensor within specification?
page FT-186
Key OFF.
Disconnect suspect sensor connector.
Connect a jumper wire between the sensor signal circuit and
SIG RTN circuit at the sensor connector.
Key ON.
Note: If a scan tool or NGS communication problem
exists, remove jumper wire immediately and go to step 8.
Access
ECT
or IAT
PID.
Is ECT or IAT PID less than 0.2 volt?
Yes
Replace PCM.
Go to step 15.
Replace suspect sensor.
Remove jumper wire.
Go to step 15.
Yes
Remove jumper wire.
Go to next step.
Key OFF.
Leave suspect sensor connector disconnected.
Install breakout box, leave PCM disconnected.
Measure resistance between sensor signal circuit at sensor
connector and ECT test pin
38
or IAT test pin 39 at breakout
box.
Measure resistance between SIG HTN at sensor connector
and SIG RTN test pin 91 at breakout box.
Is each resistance less than 5.0 ohms?
Yes
Replace PCM.
Go to step 15.
Repair open in sensor signal or SIG RTN circuit.
Go to step 15.