Cruise Control Move Output Circuit Low Voltage
Circuit Description
The cruise control move circuit is used to indicate to the cruise control module the amount of accelerator pedal movement needed to maintain cruise set speed. The powertrain control module (PCM) pulse width modulates (PWM) ignition voltage on the cruise control move circuit at a 100 ms PWM rate. When the cruise control clutch is commanded On, the PCM will begin to PWM the cruise control move circuit as needed. Very short On-time pulses indicate to the cruise control module to keep the accelerator pedal at the same position. The PCM monitors the cruise control move circuit for low and high voltage faults. DTC P1580 sets when the cruise control move circuit is commanded On (PWM On-time), and the feedback voltage at the PCM is low.
Conditions for Setting the DTC
DTC P1580 will set if the cruise control move feedback voltage is less than 2.5 volts with the cruise control move commanded On (PWM On-time) when:
| • | The condition exists for longer than 500 milliseconds. |
| • | The SET/COAST switch is depressed with cruise switch On and the input voltage is less than 2.63 volts or greater than 4.32 volts. |
DTC P1580 diagnostic runs continuously with engine running and the cruise control move commanded On.
DTC P1580 is a type D DTC.
Diagnostic Aids
To locate an intermittent problem, use the scan tool to monitor the C/C MOVE CKT. - LOW VOLT test with ignition On, the engine Off. When a fault (a short to ground or an open PCM driver) exists, the scan tool will display TEST FAIL.
The test will fail only when the device is being commanded On and the voltage at the PCM is low. The test updates every 100 ms whenever the ignition is turned On and the device is being commanded On via the scan tool or the PCM.
The voltage measured with a DVOM on circuit 1886 with ignition On and the cruise control module disconnected, should read ignition voltage.
