Diagnostic Test

WARNING: This page is about a different car, the 2005 Jeep Grand Cherokee. However, it is still accessible from the selected car via links, so may be relevant.

1) EGR POSITION SENSOR BELOW 0.2 OF A VOLT
Ignition on, engine not running.

With a scan tool, read the EGR Position Sensor voltage.

Is the voltage below 0.2 of a volt?

Yes
1. Go To step 2).
No
1. Go To step 9).
2) (F856) 5-VOLT SUPPLY CIRCUIT

Fig 1: Checking 5-Volt Supply Circuit
Courtesy of DAIMLERCHRYSLER CORP.

Turn the ignition off.

Disconnect the EGR Solenoid harness connector.

Ignition on, engine not running.

Measure the voltage of the (F856) 5-volt Supply circuit in the EGR Solenoid harness connector.

Is the voltage between 4.5 to 5.2 volts?

Yes
1. Go To step 3).
No
1. Go To step 6).
3) EGR POSITION
With the scan tool, monitor the EGR Position Sensor voltage.

Is the voltage above 4.5 volts?

Yes
1. Replace the EGR Solenoid Assembly.
2. Perform POWERTRAIN VERIFICATION TEST .
No
1. Go To step 4).
4) (K34) EGR POSITION SENSOR SIGNAL CIRCUIT SHORTED TO GROUND

Fig 2: Checking EGR Sensor Signal Circuit
Courtesy of DAIMLERCHRYSLER CORP.

Turn the ignition off.

Disconnect the C2 PCM harness connector.

Measure the resistance between ground and the (K34) EGR Position Sensor Signal circuit in the EGR Solenoid harness connector.

Is the resistance below 100 ohms?

Yes
1. Repair the short to ground circuit in the (K34) EGR Position Sensor Signal circuit.
2. Perform POWERTRAIN VERIFICATION TEST .
No
1. Go To step 5).
5) (K34) EGR SENSOR SIGNAL CIRCUIT SHORTED TO THE (K900) SENSOR GROUND CIRCUIT

Fig 3: Checking EGR Sensor Signal Circuit & Sensor Ground Circuit
Courtesy of DAIMLERCHRYSLER CORP.

Measure the resistance between the (K34) EGR Position Sensor Signal circuit and (K900) Sensor ground circuit in the EGR Solenoid harness connector.

Is the resistance below 100 ohms?

Yes
1. Repair the short between the (K900) Sensor ground and the (K34) EGR Position Sensor Signal circuit.
2. Perform POWERTRAIN VERIFICATION TEST .
No
1. Go To step 8).
6) (F856) 5-VOLT SUPPLY CIRCUIT SHORTED TO GROUND

Fig 4: Checking 5-Volt Supply Circuit
Courtesy of DAIMLERCHRYSLER CORP.

Turn the ignition off.

Disconnect the C1 PCM harness connector.

Measure the resistance between ground and the (F856) 5-volt Supply circuit in the EGR Solenoid harness connector.

Is the resistance below 100 ohms?

Yes
1. Repair the short to ground in the (F856) 5-volt Supply circuit.
2. Perform POWERTRAIN VERIFICATION TEST .
No
1. Go To step 7).
7) (F856) 5-VOLT SUPPLY CIRCUIT OPEN

Fig 5: Checking 5-Volt Supply Circuit
Courtesy of DAIMLERCHRYSLER CORP.

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 (F856) 5-volt Supply circuit from the EGR Solenoid harness connector to the appropriate terminal of special tool #8815.

Is the resistance below 5.0 ohms?

Yes
1. Go To step 8).
No
1. Repair the open in the (F856) 5-volt Supply circuit.
2. Perform POWERTRAIN VERIFICATION TEST .
8) 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
1. Repair as necessary.
2. Perform POWERTRAIN VERIFICATION TEST .
No
1. Replace and program the Powertrain Control Module per Service Information.
2. Perform POWERTRAIN VERIFICATION TEST .
9) 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
1. Refer to INTERMITTENT CONDITION .
2. Perform POWERTRAIN VERIFICATION TEST .
No
1. Replace the EGR Solenoid Assembly.
2. Perform POWERTRAIN VERIFICATION TEST .