Pinpoint Test A: The Speed Control Is Inoperative - No Flash Codes
Speed Control
Pinpoint Tests
Pinpoint Test A: The Speed Control Is Inoperative - No Flash Codes
Refer to wiring Diagram Set 31, Speed Control for schematic and connector information. Diagrams By Number
Normal Operation
The speed control actuator sends and receives signals to the speed control switches through circuits VES10 (WH) and RES08 (GN/BN). Voltage to the speed control actuator is supplied through circuit CBP20 (YE/VT) from the Smart Junction Box (SJB). Ground for the speed control actuator is provided by circuit GD123 (BK/GY).
When the brake pedal is applied, the stoplamp switch routes voltage through circuit CCB15 (BN/GN), sending a voltage signal to the speed control actuator. When the speed control actuator receives this input, the speed control actuator goes into a stand-by mode.
The Clutch Pedal Position (CPP) switch, if equipped, is normally closed. When the clutch is applied, ground is removed from circuit CCB15 (BN/GN) to the speed control actuator, and the actuator goes into a stand-by mode.
The speed control deactivator switch (closed when the brake pedal is not applied) routes voltage through circuit CES09 (VT/OG) to the speed control actuator. When the brake pedal is firmly pressed, the speed control deactivator switch opens and voltage is no longer supplied to the speed control actuator.
The speed control actuator receives the speed signal from the PCM through circuit VMC05 (VT/OG).
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Stoplamp switch
- CPP switch (manual transmission)
- Speed control deactivator switch
- Speed control cable
- Throttle body linkage
- Clockspring
- Speed control switch
- Speed control actuator
- SJB
- PCM
PINPOINT TEST A: THE SPEED CONTROL IS INOPERATIVE - NO FLASH CODES
NOTICE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connectors.
NOTE: It is important to use a voltage drop test on some of the tests where specified. Circuits may indicate a good voltage and continuity but may not be capable of carrying sufficient current.
NOTE: Failure to disconnect the battery when instructed will result in false resistance readings. Refer to Battery.
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A1 CHECK THE VOLTAGE TO THE SPEED CONTROL ACTUATOR
- Ignition OFF.
- Disconnect: Speed Control Actuator C122.
- Ignition ON.
- Measure the voltage between the speed control actuator C122-7, circuit CBP20 (YE/VT), harness side and ground.
- Is the voltage greater than 10 volts?
Yes
GO to A2.
No
VERIFY the SJB fuse 20 (10A) is OK. If OK, REPAIR the circuit. If not OK, REFER to the Wiring Diagrams to identify the possible causes of the circuit short. REPEAT the self-test.
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A2 CHECK THE VOLTAGE DROP ON THE SPEED CONTROL ACTUATOR VOLTAGE SUPPLY CIRCUIT
- Ignition OFF.
- Connect: Speed Control Actuator C122.
- Ignition ON.
- Measure the voltage drop on the speed control actuator C122-7, circuit CBP20 (YE/VT).
- Is the voltage drop less than 0.2 volt?
Yes
GO to A3.
No
REPAIR the circuit. REPEAT the self-test.
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A3 CHECK THE SPEED CONTROL ACTUATOR GROUND CIRCUIT FOR AN OPEN
- Ignition OFF.
- Disconnect: Negative Battery Cable.
- Disconnect: Speed Control Actuator C122.
- Measure the resistance between the speed control actuator C122-10, circuit GD123 (BK/GY), harness side and ground.
- Is the resistance less than 5 ohms?
Yes
GO to A4.
No
REPAIR the circuit. REPEAT the self-test.
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A4 CHECK THE VOLTAGE TO THE SPEED CONTROL DEACTIVATOR SWITCH
- Connect: Negative Battery Cable.
- Disconnect: Speed Control Deactivator Switch C277.
- Ignition ON.
- Measure the voltage between the speed control deactivator switch C277-1, circuit CBP26 (BU/WH), harness side and ground.
- Is the voltage greater than 10 volts?
Yes
GO to A5.
No
VERIFY the SJB fuse 26 (2A) is OK. If OK, REPAIR the circuit. REPEAT the self-test.
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A5 CHECK THE VOLTAGE DROP ON THE SPEED CONTROL DEACTIVATOR SWITCH VOLTAGE SUPPLY CIRCUIT
- Ignition OFF.
- Connect: Speed Control Deactivator Switch C277.
- Ignition ON.
- Measure the voltage drop on the speed control deactivator switch C277-1, circuit CBP26 (BU/WH).
- Is the voltage drop less than 0.2 volt?
Yes
GO to A6.
No
REPAIR the circuit. REPEAT the self-test.
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A6 CHECK THE SPEED CONTROL DEACTIVATOR SWITCH OPERATION
- Ignition OFF.
- Disconnect: Speed Control Deactivator Switch C277.
- While pressing the brake pedal firmly and releasing it, measure the resistance between the speed control deactivator switch pin 2, component side and the speed control deactivator switch pin 1, component side.
- Is the resistance less than 5 ohms with the brake pedal released and greater than 10,000 ohms with the brake pedal applied firmly?
Yes
GO to A7.
No
INSTALL a new speed control deactivator switch. REFER to Speed Control Deactivator Switch Speed Control Deactivator Switch. TEST the system for normal operation.
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A7 CHECK THE SPEED CONTROL DEACTIVATOR SWITCH SIGNAL CIRCUIT FOR AN OPEN
- Ignition OFF.
- Measure the resistance between the speed control deactivator switch C277-2, circuit CES09 (VT/OG), harness side and the speed control actuator C122-9, circuit CES09 (VT/OG), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to A8.
No
REPAIR the circuit. REPEAT the self-test.
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A8 CHECK THE VOLTAGE DROP ON THE SPEED CONTROL DEACTIVATOR SWITCH SIGNAL CIRCUIT
- Connect: Speed Control Actuator C122.
- Connect: Speed Control Deactivator Switch C277.
- Ignition ON.
- Measure the voltage drop on the speed control actuator C122-9, circuit CES09 (VT/OG).
- Is the voltage drop less than 0.2 volt?
Yes
GO to A9.
No
REPAIR the circuit. REPEAT the self-test.
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A9 CHECK THE SPEED CONTROL SWITCH SIGNAL CIRCUIT FOR A SHORT TO GROUND
- Ignition OFF.
- Disconnect: Speed Control Actuator C122.
- Measure the resistance between the speed control actuator C122-5, circuit VES10 (WH), harness side and ground.
- Is the resistance greater than 10,000 ohms?
Yes
GO to A10.
No
GO to A11.
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A10 CHECK THE SPEED CONTROL SWITCH SIGNALS
- Measure the resistance between the speed control actuator C122-5, circuit VES10 (WH), harness side and the speed control actuator C122-6, circuit RES08 (GN/BN), harness side while pressing the speed control switches as follows:
- Are the resistance values OK?
Yes
GO to A13.
No
GO to A11.
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A11 CHECK THE CIRCUITS TO THE CLOCKSPRING FOR AN OPEN OR SHORT TO GROUND
- Ignition OFF.
- Disconnect: Clockspring C218a.
- Measure the resistance between the speed control actuator, harness side and the clockspring, harness side; and between the speed control actuator, harness side and ground as follows:
- Is the resistance less than 5 ohms between the speed control actuator and the clockspring, and greater than 10,000 ohms between the speed control actuator and ground?
Yes
GO to A12.
No
REPAIR the circuit. TEST the system for normal operation.
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A12 CHECK THE SPEED CONTROL SWITCHES
- Disconnect: Clockspring C218c.
- Measure the resistance between the clockspring C218c-3, harness side and the clockspring C218c-8, harness side with no switches pressed and then while pressing the speed control switches as follows:
- Are the speed control switch resistance values OK?
Yes
INSTALL a new clockspring. TEST the system for normal operation.
No
INSTALL a new speed control switch. REFER to Speed Control Switch Speed Control Switch. TEST the system for normal operation.
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A13 CHECK THE SPEED CONTROL ON SWITCH FOR VOLTAGE
- Ignition ON.
- While pressing and releasing the speed control ON switch, measure the voltage between the speed control actuator C122-5, circuit VES10 (WH), harness side and ground.
- Is the voltage greater than 10 volts with the speed control ON switch pressed and 0 volt with the speed control ON switch released?
Yes
GO to A19.
No
If the voltage is always 0 volt, GO to A14.
Otherwise, GO to A18.
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A14 CHECK THE SPEED CONTROL ON/OFF SWITCH VOLTAGE SUPPLY CIRCUIT FOR AN OPEN
- Ignition OFF.
- Disconnect: Speed Control ON/OFF Switch C2178.
- Ignition ON.
- Measure the voltage between the speed control ON/OFF switch C2178-3, circuit CBP20 (YE/VT), harness side and ground.
- Is the voltage greater than 10 volts?
Yes
GO to A17.
No
GO to A15.
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A15 CHECK THE SPEED CONTROL ON/OFF SWITCH CIRCUIT FOR AN OPEN
- Ignition OFF.
- Disconnect: Clockspring C218c.
- Measure the resistance between the clockspring C218c-6, circuit CBP20 (YE/VT), harness side and the speed control ON/OFF switch C2178-3, circuit CBP20 (YE/VT), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to A16.
No
REPAIR the circuit. TEST the system for normal operation.
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A16 CHECK THE SPEED CONTROL ON/OFF SWITCH VOLTAGE SUPPLY CIRCUIT FOR VOLTAGE
- Ignition OFF.
- Disconnect: Clockspring C218a.
- Ignition ON.
- Measure the voltage between the clockspring C218a-1, circuit CBP20 (YE/VT), harness side and ground.
- Is the voltage greater than 10 volts?
Yes
INSTALL a new clockspring. TEST the system for normal operation.
No
VERIFY the SJB fuse 20 (10A) is OK. If OK, REPAIR the circuit. If not OK, REFER to Wiring Diagrams to identify the possible causes of the circuit short.
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A17 CHECK THE SPEED CONTROL ON/OFF SWITCH OPERATION
- Ignition OFF.
- While pressing and releasing the speed control ON switch, measure the resistance between the speed control ON/OFF switch C2178, pin 3, component side and the speed control ON/OFF switch C2178, pin 2, component side.
- Is the resistance between 950 and 1,050 ohms with the switch pressed, and greater than 10,000 ohms with the switch released?
Yes
REPAIR circuit 151 (LB/BK) for an open. TEST the system for normal operation.
No
INSTALL a new speed control switch. REFER to Speed Control Switch Speed Control Switch. TEST the system for normal operation.
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A18 CHECK CIRCUIT VES10 (WH) FOR A SHORT TO VOLTAGE
- Ignition OFF.
- Disconnect: Clockspring C218a.
- Ignition ON.
- Measure the voltage between the speed control actuator C122-5, circuit VES10 (WH), harness side and ground.
- Is any voltage present?
Yes
REPAIR the circuit. TEST the system for normal operation.
No
INSTALL a new clockspring. TEST the system for normal operation.
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A19 CHECK THE STOPLAMPS FOR CORRECT OPERATION
- Ignition OFF.
- Check the stoplamps and high mounted stoplamp for correct operation by applying and releasing the brake pedal.
- Do the stoplamps and high mounted stoplamp operate correctly?
Yes
GO to A20.
No
REFER to Lighting and Horns to continue diagnosis of the stoplamps. Testing and Inspection
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A20 CHECK THE STOPLAMP SWITCH CIRCUIT
NOTE: Some vehicles equipped with an automatic transmission have wiring to the CPP switch, with a jumper plug installed in C257. If the CPP switch wiring and C257 are present, carry out the pinpoint test steps for the CPP circuits as directed.
- Measure the resistance between the speed control actuator C122-4, circuit CCB15 (BN/GN), harness side and the speed control actuator C122-10, circuit GD123 (BK/GY), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to A25.
No
If equipped with a manual transmission or an automatic transmission with CPP wiring, GO to A21.
Otherwise, GO to A23.
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A21 CHECK THE STOPLAMP SWITCH SIGNAL CIRCUIT FOR AN OPEN TO THE CPP SWITCH
- Disconnect: CPP Switch (or Jumper Plug) C257.
- Measure the resistance between the CPP switch (or jumper plug) C257-3, circuit CCB15 (BN/GN), harness side and ground.
- Is the resistance less than 5 ohms?
Yes
GO to A22.
No
GO to A23.
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A22 CHECK THE STOPLAMP SWITCH SIGNAL CIRCUIT FOR AN OPEN
- Measure the resistance between the speed control actuator C122-4, circuit CCB15 (BN/GN), harness side and the CPP switch (or jumper plug) C257-3, circuit CCB15 (BN/GN), harness side.
- Is the resistance less than 5 ohms?
Yes
INSTALL a new CPP switch (or jumper plug). REPEAT the self-test.
No
REPAIR the circuit. REPEAT the self-test.
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A23 CHECK THE STOPLAMP SWITCH GROUND CIRCUIT FOR AN OPEN
- Disconnect: Negative Battery Cable.
- Disconnect: Stoplamp Switch C278.
- Measure the resistance between the stoplamp switch C278-5, circuit GD161 (BK/YE), harness side and ground.
- Is the resistance less than 5 ohms?
Yes
GO to A24.
No
REPAIR the circuit. REPEAT the self-test.
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A24 CHECK THE STOPLAMP SWITCH
- Connect: Negative Battery Cable.
- Disconnect: Stoplamp Switch C278.
- Install a fused jumper wire between the stoplamp switch C278-4, circuit CCB15 (BN/GN), harness side and the stoplamp switch C278-5, circuit GD161 (BK/YE), harness side.
- Measure the resistance between the speed control actuator C122-4, circuit CCB15 (BN/GN), harness side and the speed control actuator C122-10, circuit GD123 (BK/GY), harness side.
- Is the resistance less than 5 ohms?
Yes
INSTALL a new stoplamp switch. REPEAT the self-test.
No
REPAIR the circuit. REPEAT the self-test.
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A25 CHECK THE VEHICLE SPEED SIGNAL CIRCUIT FOR AN OPEN
- Ignition OFF.
- Disconnect: PCM C175b.
- Measure the resistance between the speed control actuator C122-3, circuit VMC05 (VT/OG), harness side and the PCM C175b-1, circuit VMC05 (VT/OG), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to A26.
No
REPAIR the circuit. REPEAT the self-test.
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A26 CHECK THE VEHICLE SPEED SIGNAL VOLTAGE
NOTICE: Make sure the vehicle is secured correctly before attempting to place the transmission range selector lever in DRIVE (D) or in 1st gear, if equipped with a manual transmission.
- Connect: Speed Control Deactivator Switch C277.
- Connect: PCM C175b.
- Jack up the drive wheels and chock the other wheels.
- NOTE: For vehicles equipped with a manual transmission, place the transmission into 1st gear.
- Start the vehicle, place the transmission in DRIVE (D), and with the engine at idle, allow the drive wheels to spin.
- Measure and record the AC voltage between the speed control actuator C122-3, circuit VMC05 (VT/OG), harness side and ground with the vehicle drive 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 A27.
No
GO to A29.
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A27 CHECK THE VEHICLE SPEED SIGNAL FREQUENCY
NOTICE: Make sure the vehicle is secured correctly before attempting to place the transmission range selector lever in DRIVE (D), or in 1st gear, if equipped with a manual transmission.
- NOTE: For vehicles equipped with a manual transmission, place the transmission into 1st gear.
- Start the vehicle, place the transmission in DRIVE (D), and with the engine at idle, allow the drive wheels to spin.
- Measure and record the frequency between the speed control actuator C122-3, circuit VMC05 (VT/OG), harness side and ground with the vehicle drive 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 speed control actuator. REFER to Speed Control Actuator Service and Repair. REPEAT the self-test.
No
GO to A28.
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A28 CHECK THE VEHICLE SPEED SIGNAL FOR A SHORT TO GROUND
- Measure the resistance between the speed control actuator C122-3, circuit VMC05 (VT/OG), harness side and ground.
- Is the resistance greater than 10,000 ohms?
Yes
GO to A29.
No
REPAIR the circuit. REPEAT the self-test.
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A29 CHECK FOR CORRECT PCM OPERATION
- Connect: All Disconnected Connectors.
- Disconnect the PCM connector.
- 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. REPEAT the self-test.
No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.
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