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DTC P1597-A: Speed Control Switch Always Low

NOTE: For connector terminal ID, see CONNECTOR IDENTIFICATION . For wiring diagram, see WIRING DIAGRAMS article.
  1. Using scan tool, read speed control ON/OFF switch voltage. If voltage is less than one volt, go to next step. If voltage is one volt or more, condition to set trouble code is not present at this time. SPEED CONTROL SWITCH ALWAYS LOW DTC sets when switch voltage is less than 4.5 volts for 2 minutes. Possible causes are: speed control switch shorted, PCM failure, speed control switch signal circuit shorted or shorted speed control switch. Perform TEST VER-4A: SPEED CONTROL VERIFICATION .
  2. Using scan tool, still observing speed control switch ON/OFF voltage, disconnect speed control ON/OFF switch 2-pin connector. If voltage changed to 5 volts, replace speed control ON/OFF switch. Perform TEST VER-4A: SPEED CONTROL VERIFICATION . If voltage did not change to 5 volts, go to next step.
  3. Using scan tool, still observing speed control ON/OFF switch voltage, disconnect speed control RESUME/ACCEL switch connector. If voltage changed to 5 volts, replace speed control ON/OFF switch. Perform TEST VER-4A: SPEED CONTROL VERIFICATION . If voltage did not change to 5 volts, go to next step.
  4. Using a DVOM, check resistance of speed control signal circuit at speed control ON/OFF switch connector. 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 signal circuit. Perform TEST VER-4A: SPEED CONTROL VERIFICATION .
  5. Disconnect Powertrain Control Module (PCM) connector. Using a DVOM, check resistance of speed control switch signal circuit between speed control ON/OFF switch 2-pin connector and ground. See SPEED CONTROL SWITCH 2-PIN CONNECTOR WIRE IDENTIFICATION  table. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, replace PCM. Perform TEST VER-4A: SPEED CONTROL VERIFICATION .
  6. Disconnect clock spring 5-pin connector. Using a DVOM, check resistance of speed control switch signal circuit between clock spring connector and PCM connector terminal No. 41. See CLOCK SPRING 5-PIN CONNECTOR WIRE IDENTIFICATION  table and PCM CONNECTOR WIRE IDENTIFICATION  table. If resistance is less than 5 ohms, repair short to ground on speed control switch signal circuit. Perform TEST VER-4A: SPEED CONTROL VERIFICATION . If resistance is 5 ohms or more, replace clock spring. Perform TEST VER-4A: SPEED CONTROL VERIFICATION .
SPEED CONTROL SWITCH 2-PIN CONNECTOR WIRE IDENTIFICATION

Application Wire Color
Speed Control Switch Ground Circuit Black/Light Green
Speed Control Switch Signal Circuit Red/Light Green
CLOCK SPRING 5-PIN CONNECTOR WIRE IDENTIFICATION

Application Wire Color
Speed Control Switch Signal Circuit Red/Light Green
PCM CONNECTOR WIRE IDENTIFICATION

Application Wire Color
PCM Terminal No. 41
Speed Control Switch Signal Circuit Red/Light Green
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