INSPECTION PROCEDURE 7: Hunting (Repeated Acceleration and Deceleration) Occurs at the Set Vehicle Speed. < M/T >: Diagnosis

WARNING: This page is about a different car, the 2005 Dodge Stratus and 2005 Chrysler Sebring. However, it is still accessible from the selected car via links, so may be relevant.

Required Special Tool:

MB991223: Harness Set

STEP 1. Check the vehicle speed sensor.
1. Remove the vehicle speed sensor and connect a 3 - 10 kΩ resistor as shown in the illustration.
2. Turn the shaft of the vehicle speed sensor and check that there is voltage between terminals 2 - 3. (one turn = four pulses.)
Q: Is the voltage within specifications?

YES : Go to Step 2.

NO: Replace the vehicle speed sensor. (Refer to COMBINATION METER ASSEMBLY AND VEHICLE SPEED SENSOR ). Then check that the malfunction is eliminated.

Fig 1: Checking Voltage Between Vehicle Speed Sensor
Courtesy of DAIMLERCHRYSLER CORPORATION
STEP 2. Check the auto-cruise vacuum pump.
1. Disconnect the vacuum hose from the auto-cruise vacuum pump and connect a vacuum gauge to the vacuum pump.
2. Disconnect the vacuum pump connector.
3. Check the auto-cruise vacuum pump and valves according to the following procedure:
  1. Connect the positive battery terminal to auto-cruise vacuum pump connector terminal 1, and the negative battery terminal to terminals 2, 3, and 4. Then the vacuum gauge should read 27 kPa (8.0 in.Hg) or more.
  2. The vacuum should be maintained when terminal 4 is disconnected from the negative battery terminal while terminals 1, 2, and 3 remain connected. Then the vacuum gauge should read 0 kPa (0 in.Hg) when terminal 2 is disconnected from the negative battery terminal while terminals 1, and 3 remain connected.
  3. The vacuum should be maintained when terminal 4 is disconnected from the negative battery terminal while terminals 1, 2, and 3 remain connected. Then the vacuum gauge should read 0 kPa (0 in.Hg) when terminal 3 is disconnected from the negative battery terminal while terminals 1, and 2 remain connected.
Q: Are all of the above values satisfied?

YES : Go to Step 3.

NO: Replace the auto-cruise vacuum pump. (Refer to AUTO-CRUISE CONTROL ). Then that the malfunction is eliminated.

Fig 2: Checking Auto-Cruise Vacuum Pump
Courtesy of DAIMLERCHRYSLER CORPORATION
STEP 3. Check the vacuum actuator.
1. Disconnect the vacuum hose from the vacuum actuator, and then connect a hand vacuum pump to the vacuum actuator.
2. Apply a vacuum and check that the throttle lever moves and the vacuum is maintained.
Q: Is the vacuum actuator damaged?

YES : Replace the vacuum actuator. (For 2.4L engine, refer to THROTTLE BODY ASSEMBLY ). (For 3.0L engine, refer to THROTTLE BODY ASSEMBLY ). Then check that the malfunction is eliminated.

NO: Check that the malfunction is eliminated. If the malfunction is eliminated, replace the auto-cruise control-ECU. (Refer to AUTO-CRUISE CONTROL ). Then check that the malfunction is eliminated.

Fig 3: Checking Vacuum Actuator
Courtesy of DAIMLERCHRYSLER CORPORATION