Page 187 of 5267

3.ENGINE MECHANICAL
Check for any of the following conditions/mechanical problems.
AIR INDUCTION SYSTEM - must be free from leaks
ENGINE VACUUM - must be at least 13 inches in neutral
ENGINE VALVE TIMING - must be within specifications
ENGINE COMPRESSION - must be within specifications
ENGINE EXHAUST SYSTEM - must be free of any restrictions or leaks
ENGINE PCV SYSTEM - must flow freely
TORQUE CONVERTER STALL SPEED - must be within specifications
POWER BRAKE BOOSTER - no internal vacuum leaks
FUEL - must be free of contamination
FUEL INJECTOR - plugged or restricted injector; control wire not connectedtocorrectinjector
Are there any engine mechanical problems?
Ye s>>
Repair as necessary.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
No>>
Go To 4
4.O2 SENSOR
Ignition on, engine not running.
Disconnect the 2/2 O2 Sensor harness connector.
With the scan tool, monitor the 2/2 O2 Sensor voltage.
The O2 Sensor voltage should read 5.0 volts on the scan tool with the
connector disconnected.
Using a jumper wire, jump the (K243) O2 Sensor 2/2 Signal circuit to
the (K904) O2 Return Downstream circuit in the O2 Sensor harness
connector.
NOTE: The voltage should drop from 5.0 volts to 2.5 volts with the
jumper wire in place.
Did the O2 Sensor volts change from 5.0 volts to 2.5 volts?
Ye s>>
Replace the O2 Sensor
Perform the POWERTRAIN VERIFICATION TEST. (Refer to
9 - ENGINE - STANDARD PROCEDURE)
No>>
Go To 5
Page 188 of 5267
5.(K243) O2 SENSOR 2/2 SIGNAL CIRCUIT
Remove the jump wire.
Ignition on, engine not running.
With the scan tool, monitor the O2 Sensor voltage.
Is the voltage above 4.8 volts?
Ye s>>
Go To 6
No>>
Check the (K243) O2 Sensor 2/2 Signal circuit for a open or
short to voltage. Inspect the O2 Sensor connector and the
PCM harness connector. If OK, replace and program the
Powertrain Control Module per Service Information.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to
9 - ENGINE - STANDARD PROCEDURE)
6.(K399) O2 SENSOR 2/2 HEATER CONTROL CIRCUIT SHORTED TO GROUND
Turn the ignition off.
Disconnect the C3 PCM harness connector.
Measure the resistance between ground and the (K399) O2 Sensor 2/2
Heater Control circuit in the O2 Sensor harness connector.
Is the resistance below 5.0 ohms?
Ye s>>
Repair the short to ground in the (K399) O2 Sensor 2/2
Heater Control circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to
9 - ENGINE - STANDARD PROCEDURE)
No>>
Go To 7
Page 189 of 5267
7.(K904) O2 RETURN DOWNSTREAM CIRCUIT
Measure the voltage on the (K904) O2 Return Downstream circuit in the
O2 Sensor harness connector.
Is the voltage at 2.5 volts?
Ye s>>
Check the fuel system for contaminants.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to
9 - ENGINE - STANDARD PROCEDURE)
No>>
Check the (K904) O2 Downstream Return circuit for a short
to ground, open, or short to voltage. Inspect the O2 Sensor
connector and the PCM harness connector. If OK, replace
and program the Powertrain Control Module per Service
Information.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to
9 - ENGINE - STANDARD PROCEDURE)
Page 191 of 5267

When Monitored:
With the engine running in closed loop mode, the ambient/battery temperature above (-7°C) 20°F, altitude
below 8500 ft.
Set Condition:
If the PCM multiplies short term compensation by long term adaptive as wellas a purge fuel multiplier and the
result is below a certain value for 30 seconds over two trips, a freeze frameis stored, the MIL illuminates and
a trouble code is stored. Two Trip Fault. Three good trips to turn off the MIL.
Possible Causes
EXHAUST LEAK
ENGINE MECHANICAL
2/2O2SENSOR
(K342) O2 SENSOR 2/2 SIGNAL CIRCUIT
(K399) O2 SENSOR 2/2 HEATER CONTROL CIRCUIT
(K904) O2 RETURN DOWNSTREAM CIRCUIT
FUEL CONTAMINATION
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE -
DIAGNOSIS AND TESTING).
Diagnostic Test
1.ACTIVE DTC
NOTE: Check the vehicle repair history. If the 2/2 O2 has been replaced makesure that the O2 sensor was
properly installed and meets OEM specification.
NOTE: Check for contaminants that may have damaged the O2 Sensor: contaminated fuel, unapproved sil-
icone, oil and coolant.
Ignition on, engine not running.
With a scan tool, read DTCs.
Is the DTC active at this time?
Ye s>>
Go To 2
No>>
Refer to the INTERMITTENT CONDITION Diagnostic Procedure.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
2.EXHAUST LEAK
Turn the ignition off.
WARNING: To avoid personal injury from the exhaust system being hot, allowthe exhaust to cool down to
a safe temperature before performing a physical inspection. Failure to follow these instructions can result in
personal injury or death.
Visually and Physically inspect the exhaust system for holes, cracks and blockage in the exhaust system.
Is the exhaust system is good condition?
Ye s>>
Go To 3
No>>
Repair or Replace as necessary.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
Page 192 of 5267

3.ENGINE MECHANICAL
Check for any of the following conditions/mechanical problems.
AIR INDUCTION SYSTEM - must be free from leaks
ENGINE VACUUM - must be at least 13 inches in neutral
ENGINE VALVE TIMING - must be within specifications
ENGINE COMPRESSION - must be within specifications
ENGINE EXHAUST SYSTEM - must be free of any restrictions or leaks
ENGINE PCV SYSTEM - must flow freely
TORQUE CONVERTER STALL SPEED - must be within specifications
POWER BRAKE BOOSTER - no internal vacuum leaks
FUEL - must be free of contamination
FUEL INJECTOR - plugged or restricted injector; control wire not connectedtocorrectinjector
Are there any engine mechanical problems?
Ye s>>
Repair as necessary.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
No>>
Go To 4
4.O2 SENSOR
Ignition on, engine not running.
Disconnect the 2/2 O2 Sensor harness connector.
With the scan tool, monitor the 2/2 O2 Sensor voltage.
The O2 Sensor voltage should read 5.0 volts on the scan tool with the
connector disconnected.
Using a jumper wire, jump the (K243) O2 Signal 2/2 circuit to the
(K904) O2 Return Downstream circuit in the O2 Sensor harness con-
nector.
NOTE: The voltage should drop from 5.0 volts to 2.5 volts with the
jumper wire in place.
Did the O2 Sensor volts change from 5.0 volts to 2.5 volts?
Ye s>>
Replace the O2 Sensor
Perform the POWERTRAIN VERIFICATION TEST. (Refer to
9 - ENGINE - STANDARD PROCEDURE)
No>>
Go To 5
Page 193 of 5267
5.(K243) O2 SENSOR 2/2 SIGNAL CIRCUIT
Remove the jump wire.
Ignition on, engine not running.
With the scan tool, monitor the 2/2 O2 Sensor voltage.
Is the voltage above 4.8 volts?
Ye s>>
Check the (K243) O2 Sensor 2/2 Signal circuit for an open
or short to battery voltage. Inspect the O2 Sensor connector
and the PCM harness connector. If OK, replace and pro-
gram the Powertrain Control Module per Service Informa-
tion.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to
9 - ENGINE - STANDARD PROCEDURE)
No>>
Go To 6
Page 194 of 5267

6.(K399) O2 SENSOR 2/2 HEATER CONTROL CIRCUIT OPEN
Turn the ignition off.
Disconnect the C3 PCM harness connector.
Measure the resistance of the (K399) O2 Sensor 2/2 Heater Control cir-
cuit from the O2 Sensor harness connector to the appropriate terminal
of special tool #8815.
Is the resistance below 5.0 ohms?
Ye s>>
Go To 7
No>>
Repair the open in the (K399) O2 Sensor 2/2 Heater Con-
trol circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to
9 - ENGINE - STANDARD PROCEDURE)
7.(K904) O2 RETURN DOWNSTREAM CIRCUIT
Measure the voltage on the (K904) O2 Return Downstream circuit in the
O2 Sensor harness connector.
Is the voltage at 2.5 volts?
Ye s>>
Check the fuel system for contaminants.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to
9 - ENGINE - STANDARD PROCEDURE)
No>>
Check the (K904) O2 Downstream Return circuit for a short
to ground, open, or short to voltage. Inspect the O2 Sensor
connector and the PCM harness connector. If OK, replace
and program the Powertrain Control Module per Service
Information.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to
9 - ENGINE - STANDARD PROCEDURE)
Page 197 of 5267

When Monitored:
With the ignition on and the ETC Motor is not in Limp Home mode.
Set Condition:
When the PCM detects an internal error or a short between the ETC Motor - and ETC Motor + circuits in the
ETC Motor Driver. One trip fault. ETC light is flashing.
Possible Causes
THROTTLE PLATE / BORE INSPECTION
(K447) ETC POSITIVE CIRCUIT SHORTED TO BATTERY VOLTAGE
(K448) ETC NEGATIVE CIRCUIT SHORTED TO BATTERY VOLTAGE
(K447) ETC POSITIVE CIRCUIT SHORTED TO THE (K448) ETC NEGATIVE CIRCUIT
(K447) ETC POSITIVE CIRCUIT OPEN
(K447) ETC POSITIVE CIRCUIT SHORTED TO GROUND
(K448) ETC NEGATIVE CIRCUIT OPEN
(K448) ETC NEGATIVE CIRCUIT SHORTED TO GROUND
LOW BATTERY VOLTAGE
ETC MOTOR/THROTTLE BODY
PCM
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE -
DIAGNOSIS AND TESTING).
Diagnostic Test
1.ACTIVE DTC
Ignition on, engine not running.
NOTE: If the P2100 is intermittent, it is possible that the controller is overheating in extreme hot tempera-
tures, and this is considered a normal protection operation. No repair is necessary.
NOTE: Low battery voltage can also cause excessive current draw, in very hot and very cold ambient tem-
peratures. Make sure the battery can pass a load test before continuing.
With a scan tool, read DTCs.
Look closely at the temperatures at which this DTC set.
Is the DTC active at this time?
Ye s>>
Go To 2
No>>
Refer to the INTERMITTENT CONDITION Diagnostic Procedure.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
2.THROTTLE PLATE INSPECTION
Turn the ignition off.
Remove the Air Cleaner Assembly from the Throttle Body.
Check for any signs of a foreign material (ice or dirt) on the Throttle Plateor in the bore causing the Throttle Plate
to stick.
Were any signs of foreign material or scoring of the throttle plate or bore found?
Ye s>>
Remove the debris if possible or replace the Throttle Body Assembly. Disconnect the Battery when
replacing the Throttle Body Assembly. After installation is complete, use a scan tool and select the ETC
RELEARN function.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
No>>
Go To 3