Join Date: Aug 2009
Location: Vancouver, BC
burned is offline
Re: 4.3 misfire
DTC P0113 - IAT SENSOR CIRCUIT HIGH VOLTAGE
NOTE: For circuit reference, see the L - WIRING DIAGRAMS article.
Intake Air Temperature (IAT) sensor is a thermistor that varies resistance based on temperature. As temperature of sensor
increases, resistance decreases. Low temperature will result in a high
signal voltage. DTC will set when VCM sees an IAT sensor voltage of
greater than 5 volts.
Conditions required to set DTC are:
* No ECT sensor related DTCs.
* No VSS DTCs are set.
* No MAF sensor related DTCs.
* Vehicle speed is less than 2 MPH.
* MAF value is less than 250 grams per second.
* ECT is greater than 84.7 F (29.3 C).
* Engine run time is greater than 100 seconds.
* IAT voltage is greater than 4.9 volts.
1) Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. See the
F - BASIC TESTING - 4.3L article. Retrieve and record FREEZE FRAME
and/or FAIL RECORDS data for each DTC set. Go to next step.
2) Start engine and allow to idle. Using scan tool, read IAT
sensor voltage. If voltage is greater than 4.9 volts, go to next step.
If voltage is not greater than 4.9 volts, go to step 6).
3) Turn engine off. Turn ignition on. Disconnect IAT sensor
harness connector. Connect a jumper wire across IAT sensor harness
connector. If voltage is less than 0.82 volt, go to step 7). If
voltage is not less than 0.82 volt, go to next step.
4) Connect jumper wire between IAT sensor harness connector
signal circuit and chassis ground. If voltage is less than 0.82 volt,
go to step 8). If voltage is not less than 0.82 volt, go to next step.
5) If DTC P0123 is also set, go to DTC P0123. If DTC is not
set, go to step 9).
6) DTC P0113 is intermittent. If any additional DTCs are set,
diagnose affected DTCs. If no additional DTCs are set, see DIAGNOSTIC
7) Inspect VCM and IAT sensor for proper connection. If a
problem is found, go to step 10). If connections are okay, go to step
8) Check IAT sensor harness connector ground circuit for open
between VCM and IAT sensor. If open is found, go to step 10). If open
is not found, go to step 12).
9) Check IAT sensor harness connector signal circuit for open
between VCM and IAT sensor. If open is found, go to next step. If open
is not found, go to step 12).
10) Repair circuit as necessary. After repairs, go to step
11) Replace IAT sensor. After replacing sensor, go to step
12) Replace VCM. Program replacement VCM using required
equipment. After replacing VCM, go to next step.
13) Using scan tool, select DTC, CLEAR INFO function. Start
engine and allow it to reach operating temperature. Using scan tool,
select DTC, SPECIFIC function and enter DTC P0113. Operate vehicle
within conditions required to set DTC. If scan tool displays RAN AND
PASSED, go to next step. If scan tool does not display RAN AND PASSED,
return to step 2).
14) Using scan tool, select Read and Record INFO, REVIEW INFO
function. If any undiagnosed DTCs are displayed, diagnose affected
DTCs. If no DTCs are displayed, system is okay.