Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Pinpoint Test A: The Speed Control Is Inoperative
- A1 CHECK THE SPEED CONTROL CABLE/THROTTLE BODY LINKAGE
- Key in OFF position.
- Visually inspect the speed control cable connections, the throttle body linkage, and the speed control actuator pulley cover.
- Are the speed control cable connections, the throttle body linkage, and the speed control actuator pulley cover OK?
Yes : GO to A2.
No : INSTALL a new speed control cable or REPAIR the throttle body linkage. To INSTALL a new speed control cable, REFER to SPEED CONTROL CABLE in this article. TEST the system for normal operation. For repair of the throttle body linkage, REFER to FUEL SYSTEM-GENERAL INFORMATION . TEST the system for normal operation. For repair of the speed control actuator pulley cover, INSTALL the cover correctly. TEST the system for normal operation.
- A2 CHECK CIRCUIT 151 (LB/BK) FOR A SHORT TO GROUND
- Disconnect: Speed Control Actuator C122.
- Measure the resistance between the speed control actuator C122-5, circuit 151 (LB/BK), harness side and ground.
- Is the resistance greater than 10,000 ohms?
Yes : GO to A3.
No : GO to A4.
- A3 CHECK THE SPEED CONTROL SWITCH INPUT
- Measure the resistance between the speed control actuator C122-5, circuit 151 (LB/BK), harness side and the speed control actuator C122-6, circuit 848 (DG/OG), harness side with no buttons pressed and then while pressing the speed control switches as follows:SPEED CONTROL SWITCH RESISTANCE SPECIFICATIONS
Speed Control Switch Resistance Value COAST Between 114 and 126 ohms SET/ACCEL Between 646 and 714 ohms RESUME Between 2,090 and 2,310 ohms OFF Less than 5 ohms No buttons pressed Infinite - Are the speed control switch resistance values OK?
Yes : GO to A7.
No : GO to A4.
- Measure the resistance between the speed control actuator C122-5, circuit 151 (LB/BK), harness side and the speed control actuator C122-6, circuit 848 (DG/OG), harness side with no buttons pressed and then while pressing the speed control switches as follows:
- A4 CHECK CIRCUIT 151 (LB/BK) FOR AN OPEN OR FOR A SHORT TO GROUND
- Key in OFF position.
- Disconnect: Clockspring C218a.
- Measure the resistance between the speed control actuator C122-5, circuit 151 (LB/BK), harness side and the clockspring C218a-2, circuit 151 (LB/BK), harness side; and between the speed control actuator C122-5, circuit 151 (LB/BK), harness side and ground.
- 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 A5.
No : REPAIR the circuit. TEST the system for normal operation.
- A5 CHECK CIRCUIT 848 (DG/OG) FOR AN OPEN
- Measure the resistance between the speed control actuator C122-6, circuit 848 (DG/OG), harness side and the clockspring C218a-3, circuit 848 (DG/OG), harness side.
- Is the resistance less than 5 ohms?
Yes : GO to A6.
No : REPAIR the circuit. TEST the system for normal operation.
- A6 CHECK THE SPEED CONTROL SWITCHES
- Disconnect: Speed Control Switch Wiring Harness.
- Measure the resistance between the speed control switch connector pin 1, harness side and the speed control switch connector pin 2, harness side with no buttons pressed and then while pressing the speed control switches as follows:SPEED CONTROL SWITCH RESISTANCE SPECIFICATIONS
Speed Control Switch Resistance Value COAST Between 114 and 126 ohms SET/ACCEL Between 646 and 714 ohms RESUME Between 2,090 and 2,310 ohms OFF Less than 5 ohms No buttons pressed Infinite - Are the speed control switch resistance values OK?
Yes : INSTALL a new clockspring. REFER to SUPPLEMENTAL RESTRAINT SYSTEM . TEST the system for normal operation.
No : INSTALL a new speed control switch. REFER to SPEED CONTROL SWITCH in this article. TEST the system for normal operation.
- A7 CHECK THE SPEED CONTROL ON SWITCH OPERATION
- Key in ON position.
- While pressing the speed control switch ON, measure the voltage between the speed control actuator C122-5, circuit 151 (LB/BK) harness side and ground.
- Is the voltage greater than 10 volts?
Yes : GO to A11.
No : GO to A8.
- A8 CHECK FOR VOLTAGE TO THE SPEED CONTROL SWITCH WIRING HARNESS
- Key in OFF position.
- Disconnect: Speed Control Switch Wiring Harness.
- Key in ON position.
- Measure the voltage between the top of the clockspring pin 3, harness side and ground.
- Is the voltage greater than 10 volts?
Yes : INSTALL a new speed control switch. REFER to SPEED CONTROL SWITCH in this article. TEST the system for normal operation.
No : GO to A9.
- A9 CHECK THE CLOCKSPRING
- Key in OFF position.
- Disconnect: Clockspring C218a.
- Key in ON position.
- Measure the voltage between the clockspring C218a-1, circuit 601 (LB/PK), harness side and ground.
- Is the voltage greater than 10 volts?
Yes : INSTALL a new clockspring. REFER to SUPPLEMENTAL RESTRAINT SYSTEM . TEST the system for normal operation
No : GO to A10.
- A10 CHECK CIRCUIT 601 (LB/BK) FOR AN OPEN (SPEED CONTROL SWITCH)
- Key in OFF position.
- Disconnect: SJB C2280a.
- Measure the resistance between the clockspring C218a-1, circuit 601 (LB/PK), harness side and the SJB C2280a-28, circuit 601 (LB/PK), harness side.
- Is the resistance less than 5 ohms?
Yes : GO to A40.
No : REPAIR the circuit. TEST the system for normal operation.
- A11 CHECK CIRCUIT 151 (LB/BK) FOR VOLTAGE
- Key in ON position.
- Measure the voltage between the speed control actuator C122-5, circuit 151 (LB/BK) harness side and ground.
- Is any voltage indicated?
Yes : GO to A12.
No : GO to A14.
- A12 CHECK FOR A STUCK SPEED CONTROL SWITCH
- Key in OFF position.
- Disconnect: Speed Control Switch Wiring Harness.
- Key in ON position.
- Measure the voltage between the speed control actuator C122-5, circuit 151 (LB/BK) harness side and ground.
- Is any voltage indicated?
Yes : GO to A13.
No : INSTALL a new speed control switch. REFER to SPEED CONTROL SWITCH in this article. TEST the system for normal operation.
- A13 CHECK CIRCUIT 151 (LB/BK) FOR A SHORT TO VOLTAGE
- Key in OFF position.
- Disconnect: Clockspring C218a.
- Key in ON position.
- Measure the voltage between the speed control actuator C122-5, circuit 151 (LB/BK) harness side and ground.
- Is any voltage indicated?
Yes : REPAIR the circuit. TEST the system for normal operation.
No : INSTALL a new clockspring. REFER to SUPPLEMENTAL RESTRAINT SYSTEM . TEST the system for normal operation.
- A14 CHECK FOR VOLTAGE TO THE SPEED CONTROL ACTUATOR
- Measure the voltage between the speed control actuator C122-7, circuit 601 (LB/PK), harness side and ground.
- Is the voltage greater than 10 volts?
Yes : GO to A16.
No : VERIFY the SJB fuse 34 (5A) is OK. If OK, GO to A15.
- A15 CHECK CIRCUIT 601 (LB/PK) FOR AN OPEN (SPEED CONTROL ACTUATOR)
- Key in OFF position.
- Disconnect: SJB C2280b.
- Measure the resistance between the speed control actuator C122-7, circuit 601 (LB/PK), harness side and the SJB C2280b-11, circuit 601 (LB/PK), harness side.
- Is the resistance less than 5 ohms?
Yes : GO to A40.
No : REPAIR the circuit. TEST the system for normal operation.
- A16 CHECK CIRCUIT 601 (LB/PK)
- Measure the voltage drop on the speed control actuator C122-7, circuit 601 (LB/PK).
- Is the voltage drop less than 0.2 volts?
Yes : GO to A17.
No : REPAIR the circuit. TEST the system for normal operation.
- A17 CHECK CIRCUIT 57 (BK) FOR AN OPEN
- Key in OFF position.
- Measure the resistance between the speed control actuator C122-10, circuit 57 (BK), harness side and ground.
- Is the resistance less than 5 ohms?
Yes : GO to A18.
No : REPAIR the circuit. TEST the system for normal operation.
- A18 CHECK CIRCUIT 57 (BK)
- Measure the voltage drop on the speed control actuator C122-10, circuit 57 (BK).
- Is the voltage drop less than 0.2 volts?
Yes : GO to A19.
No : REPAIR the circuit. TEST the system for normal operation.
- A19 CHECK THE STOPLAMPS FOR CORRECT OPERATION
- Key in OFF position.
- Check the stoplamps for correct operation by applying and releasing the brake pedal.
- Do the stoplamps operate correctly?
Yes : GO to A20.
No : REFER to EXTERIOR LIGHTING to continue diagnosis of the stoplamps.
- A20 CHECK THE STOPLAMP BULBS
- Check the stoplamps for the presence of aftermarket LED lights.
- Are the correct stoplamp bulbs installed?
Yes : GO to A21.
No : INSTALL the correct stoplamp bulbs. TEST the system for normal operation.
- A21 CHECK CIRCUIT 511 (LG) FOR AN OPEN
- While applying the brake pedal, measure the voltage between the speed control actuator C122-4, circuit 511 (LG), harness side and ground.
- Is the voltage greater than 10 volts?
Yes : GO to A22.
No : REPAIR the circuit. TEST the system for normal operation.
- A22 CHECK THE CLUTCH PEDAL POSITION (CPP) SWITCH OR TRANSMISSION RANGE (TR) SENSOR
- Key in OFF position.
- Disconnect: CPP Switch C2070 or TR Sensor C167.
- Select DRIVE.
NOTE: Make sure the clutch pedal is not applied.
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.