Cruise Control System Pinpoint Test 2: Set Speed Fluctuates

NOTE:

It is normal for the engine rpm to increase slightly and then drop off slowly when the clutch pedal is applied during operation.

SET SPEED FLUCTUATES - PINPOINT TEST REFERENCE

PINPOINT TEST 2		SET SPEED FLUCTUATES
STEP	INSPECTION		ACTION
1	CHECK SPEED CONTROL CABLE/THROTTLE BODY LINKAGE Key in OFF position. Remove the speed control cable from the speed control servo. Visually inspect the core wire and check the speed control cable by pulling on the cable and noting the throttle movement. Is the speed control cable OK?	Yes	Go to next step.
1		No	Install a new speed control cable or repair the throttle body linkage. For speed control cable installation, See CRUISE CONTROL ACTUATOR CABLE REMOVAL / INSTALLATION . Test the system for normal operation. See SYMPTOM TROUBLESHOOTING CHART - CRUISE CONTROL .
2	CHECK THE SPEEDOMETER Check the speedometer for correct operation by driving the vehicle. Does the speedometer fluctuate?	Yes	Repair the speedometer. See INSTRUMENT CLUSTER .
2		No	Go to next step.
3	CHECK FOR A BASE ENGINE CONCERN Drive the vehicle and determine if there is a base engine concern. Is a base engine concern present?	Yes	See SYMPTOM TROUBLESHOOTING CHART - ENGINE MECHANICAL .
3		No	Go to next step.
4	CHECK THE VEHICLE SPEED SIGNAL VOLTAGE CAUTION: Make sure the vehicle is secured properly before attempting to place the transmission range selector in DRIVE or in 1st gear if equipped with a manual transmission. Connect: BPP switch 0120-04. Connect: PCM 0140-175b. Jack up the drive wheels and chock the other wheels. Key ON engine running (KOER). NOTE: For vehicles equipped with a manual transmission, place the transmission in 1st gear. Place the transmission in DRIVE (D) and with the engine at idle, allow the wheels to spin. Measure and record the AC voltage between the cruise control servo connector 0120-101 circuit V/O, harness side and ground with the vehicle wheels spinning a minimum of 8 km/h (5 mph). Apply the brakes until the drive wheels come to a stop. Place the transmission in PARK (P), fully engage the parking brake and turn the engine OFF. Is the recorded AC voltage greater than 4.5 volts?	Yes	Go to next step.
4		No	Go to step 6.
5	CHECK THE VEHICLE SPEED SIGNAL FREQUENCY CAUTION: Make sure the vehicle is secured properly before attempting to place the transmission range selector in DRIVE or in 1st gear if equipped with a manual transmission. Key ON engine running (KOER). NOTE: For vehicles equipped with a manual transmission, place the transmission in 1st gear. Place the transmission in DRIVE (D) and with the engine at idle, allow the wheels to spin. Measure and record the frequency between the cruise control servo connector 0120-101 circuit V/O, harness side and ground with the vehicle wheels spinning a minimum of 8 km/h (5 mph). Record the speedometer reading. Apply the brakes until the drive wheels come to a stop. Place the transmission in PARK (P), fully engage the parking brake and turn the engine OFF. Divide the frequency reading by 2.2 to get a mph result and compare this to the reading of the speedometer. Does the frequency reading result match the speedometer reading?	Yes	Install a new cruise control servo. See CRUISE CONTROL SERVO REMOVAL / INSTALLATION . Repeat the self-test.
5		No	Go to next step.
6	CHECK FOR CORRECT PCM OPERATION Disconnect: PCM 0140-175b. Check for: corrosion. damaged pins. pushed-out pins. Connect the PCM connector and make sure it seats correctly. Operate the system and verify the concern is still present. Is the concern still present?	Yes	Install a new PCM. See POWERTRAIN CONTROL MODULE (PCM) REMOVAL / INSTALLATION . Repeat the self-test.
6		No	The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.