Code PO 406 is a EGR position sensor circuit high, it looks like according to my manual, that the module powertrain control unit is connected to the EGR, and that is connected to module powertrain control there are two module powertrain control.
P0406-EGR POSITION SENSOR CIRCUIT HIGH
When Monitored:
With the ignition on. Battery voltage greater than 10 volts.
Set Condition:
EGR position sensor signal is greater than 4.89. One trip Fault.
Possible Causes
(K34) EGR POSITION SENSOR SIGNAL CIRCUIT SHORTED TO THE (F856) 5-VOLT
SUPPLY CIRCUIT
(K34) EGR POSITION SENSOR SIGNAL CIRCUIT SHORTED TO BATTERY VOLTAGE
(K34) EGR POSITION SENSOR SIGNAL CIRCUIT OPEN
(K900) SENSOR GROUND CIRCUIT OPEN
EGR SOLENOID ASSEMBLY PCM
Diagnostic Test
1) EGR POSITION SENSOR VOLTAGE ABOVE 4.5 VOLTS
Start the engine.
With the scan tool, read the EGR Position Sensor voltage.
Is the voltage above 4.5 volts?
Yes
Go To 2).
No
Go To
2) (K34) EGR POSITION SENSOR SIGNAL CIRCUIT SHORTED TO THE (F856) 5-VOLT SUPPLY CIRCUIT
Checking EGR Position Circuit & 5-Volt Supply
Turn the ignition off.
Disconnect the EGR Solenoid harness connector.
Disconnect the Cl and C2 PCM harness connectors.
Measure the resistance between the (K34) EGR Position Sensor Signal circuit and the (F856)
5-volt Supply circuit in the EGR Solenoid harness connector.
Is the resistance below 100 ohms?
Yes
Repair the short between the (K34) EGR Position Sensor Signal circuit and the (F856) 5-volt Supply circuit.
Perform POWERTRAIN VERIFICATION TEST.
3) (K34) EGR POSITION SENSOR SIGNAL CIRCUIT SHORTED TO BATTERY VOLTAGE
Fig. 93: Checking EGR Position_Sensor Signal Circuit For Short To Voltage Courtesy of DAIMLERCHRYSLER CORP.
Ignition on, engine not running.
Measure the voltage on the (K34) EGR Sensor Signal circuit in the EGR Solenoid harness connector.
Is the voltage above 0 volts?
Yes
Repair the short to battery voltage in the (K34) EGR Position Sensor Signal circuit. Perform POWERTRAIN VERIFICATION TEST.
No
Go To 4).
4) EGR SOLENOID ASSEMBLY
Checking EGR Solenoid Assembly Turn the ignition off.
Connect the PCM harness connectors.
Connect a jumper wire between the (K34) EGR Position Sensor Signal circuit and the (K900) Sensor ground circuit. With the scan tool, monitor the EGR Position Sensor voltage.
Ignition on, engine not running. Is the voltage below 0.5 of a volt?
Yes
Replace the EGR Solenoid Assembly.
Perform POWERTRAIN VERIFICATION TEST.
No
NOTE: Remove the jumper wire before continuing.
5) (K34) EGR POSITION SENSOR SIGNAL CIRCUIT OPEN
Checking ECR Position Sensor Signal Circuit For Open
Courtesy of DAIMLERCHRYSLER CORP.
Turn the ignition off.
Disconnect the C2 PCM harness connector.
CAUTION: Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install Miller Special Tool #8815 to perform diagnosis. Measure the resistance of the (K34) EGR Position Sensor Signal circuit from the EGR
Solenoid harness connector to the appropriate terminal of special tool #88 15.
Is the resistance below 5.0 ohms?
Yes
Go To 6).
No
Repair the open in the (K34) EGR Position Sensor Signal circuit.
Perform POWER TRAIN VERIFICATION TEST.
6) (K900) SENSOR GROUND CIRCUIT OPEN
Checking EGR Position Sensor Ground Circit For Qpen Courtesy of DAIMLERCHRYSLER CORP.
Measure the resistance of the (K900) Sensor ground circuit from the EGR Solenoid harness connector to the appropriate terminal of special tool #8815.
Is the resistance below 30 ohms?
Yes
Go To 2).
No
Repair the open in the (K900) Sensor ground circuit.
Perform POWERTRAIN VERIFICATION TEST.
7) PCM
NOTE: Before continuing, check the PCM harness connector terminals
for corrosion, damage, or terminal push out. Repair as necessary.
Using the schematics as a guide, inspect the wire harness and connectors. Pay particular attention to all Power and Ground circuits.
Were there any problems found? Yes
Repair as necessary.
Perform POWERTRAIN VERIFICATION TEST
No
Replace and program the Power train Control Module per Service Information.
8) EGR POSITION SENSOR SWEEP
NOTE: The engine will run rough and possibly stall in the following test. Feather the accelerator pedal to keep the engine from stalling.
Start the engine.
With the scan tool, enter System Test and then EGR System Test. Push the 4=VARIABLE function.
Monitor the EGR voltage while slowly pushing the up arrow.
Is the voltage change smooth?
Yes
Refer to INTERMITTENT CONDITION.
Perform POWER TRAIN VERIFICATION TEST.
No
Replace the EGR Solenoid Assembly.
Perform POWERTRAIN VERIFICATION TEST.
I hope this was enough information good luck in many further questions let me know.
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Friday, July 31st, 2009 AT 10:31 PM
