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.
DTC P1683-A: Speed Control Power Relay Circuit Or 12-Volt Driver Circuit
1999 Chrysler LHSSECTION DTC P1683-A: Speed Control Power Relay Circuit Or 12-Volt Driver Circuit
NOTE:
For connector terminal ID, see CONNECTOR IDENTIFICATION . For wiring diagram, see
WIRING DIAGRAMS article.
- Disconnect speed control servo 4-pin connector. DO NOT depress brake pedal during testing. Turn ignition on with engine off. Using scan tool, actuate speed control relay. Using a 12-volt test light, check voltage of speed control servo 4-pin connector brake switch output circuit. See SPEED CONTROL SERVO CONNECTOR WIRE IDENTIFICATION table. If test light is brightly illuminated, go to step 5. If test light is not brightly illuminated, go to next step.
- Turn ignition off. Using an ohmmeter, check resistance of speed control servo 4-pin connector brake switch output circuit to ground. See SPEED CONTROL SERVO CONNECTOR WIRE IDENTIFICATION table. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair short to ground on brake switch output circuit. Perform TEST VER-4A: SPEED CONTROL VERIFICATION .
- Disconnect brake switch connector. Brake switch connector is located near top of brake pedal. Turn ignition on with engine off. Using scan tool, actuate speed control solenoid. Using a 12-volt test light, check voltage of speed control power supply circuit at brake switch connector. See BRAKE SWITCH CONNECTOR WIRE IDENTIFICATION table. If test light is brightly illuminated, go to DTC P1683-B: SPEED CONTROL POWER RELAY CIRCUIT OR 12-VOLT DRIVER CIRCUIT . If test light is not brightly illuminated, go to next step.
- Turn ignition off. Disconnect Powertrain Control Module (PCM) connector. Using an ohmmeter, check resistance of speed control power supply circuit between brake switch connector and PCM connector terminal No. 5. See BRAKE SWITCH CONNECTOR WIRE IDENTIFICATION table and PCM CONNECTOR WIRE IDENTIFICATION table. If resistance is less than 5 ohms, replace PCM. Perform TEST VER-4A: SPEED CONTROL VERIFICATION . If resistance is 5 ohms or more, repair open speed control power supply circuit. Perform TEST VER-4A: SPEED CONTROL VERIFICATION .
- Turn ignition off. Using an ohmmeter, check resistance of ground circuit at speed control servo 4-pin connector. See SPEED CONTROL SERVO CONNECTOR IDENTIFICATION table. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open ground circuit. Perform TEST VER-4A: SPEED CONTROL VERIFICATION .
- Disconnect Powertrain Control Module (PCM) connectors. Using an ohmmeter, check resistance of speed control vacuum solenoid control circuit between speed control servo 4-pin connector and PCM connector terminal No. 56. See SPEED CONTROL SERVO CONNECTOR IDENTIFICATION table and PCM CONNECTOR WIRE IDENTIFICATION table. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open speed control vacuum solenoid control circuit. Perform TEST VER-4A: SPEED CONTROL VERIFICATION .
- Using an ohmmeter, check resistance of speed control vent solenoid control circuit between speed control servo 4-pin connector and PCM connector terminal No. 80. See SPEED CONTROL SERVO CONNECTOR IDENTIFICATION table and PCM CONNECTOR WIRE IDENTIFICATION table. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open speed control vent solenoid control circuit. Perform TEST VER-4A: SPEED CONTROL VERIFICATION .
- Using an ohmmeter, check resistance of speed control vacuum solenoid control circuit between speed control servo 4-pin connector and ground. See SPEED CONTROL SERVO CONNECTOR IDENTIFICATION table. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair short to ground on speed control vacuum solenoid control circuit. Perform TEST VER-4A: SPEED CONTROL VERIFICATION .
- Using an ohmmeter, check resistance of speed control vent solenoid control circuit between speed control servo 4-pin connector and ground. If resistance is less than 5 ohms, repair short to ground on speed control vent solenoid control circuit. Perform TEST VER-4A: SPEED CONTROL VERIFICATION . If resistance is 5 ohms or more, replace speed control servo. Perform TEST VER-4A: SPEED CONTROL VERIFICATION .
SPEED CONTROL SERVO CONNECTOR WIRE IDENTIFICATION
| Application | Wire Color |
|---|---|
| Brake Switch Output Circuit | Dark Blue/Red |
| Speed Control Vacuum Solenoid Control Circuit | Tan/Red |
| Speed Control Vent Solenoid Control Circuit | Light Green/Red |
| Ground | Black |
BRAKE SWITCH CONNECTOR WIRE IDENTIFICATION
| Application | Wire Color |
|---|---|
| Speed Control Power Supply Circuit | Yellow/Red |
| Speed Control Brake Switch Output Circuit | Dark Blue/Red |
PCM CONNECTOR WIRE IDENTIFICATION
| Application | Wire Color | |
|---|---|---|
| PCM Terminal No. 5 | ||
| Speed Control Power Supply Circuit | Yellow/Red | |
| PCM Terminal No. 56 | ||
| Speed Control Vacuum Solenoid Control Circuit | Tan/Red | |
| PCM Terminal No. 80 | ||
| Speed Control Vent Solenoid Control Circuit | Light Green/White | |
RENDER: 1.0x
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.