Diesel Data: Automotive Repair

P1597 Speed Control Switch Always Low

SYMPTOM
P-1597 SPEED CONTROL SWITCH ALWAYS LOW

WHEN MONITORED
With the ignition key on, and battery voltage greater than 10.4 volts.

SET CONDITION
When switch voltage is less than 4.5 volts for 2 minutes.

POSSIBLE CAUSES
- S/C signal circuit shorted to sensor ground
- S/C switch signal circuit shorted to ground
- S/C switch defective
- PCM defective