P1652

Diagnostic Chart:

Wiring Diagram:

CIRCUIT DESCRIPTION

Voltage is applied to the Vehicle Speed Output circuit by the various components which use vehicle speed data. The PCM creates the Vehicle Speed Output signal by rapidly grounding this circuit via an internal switch called a driver. The driver operates at the same rate as the Vehicle Speed Sensor (VSS) signal input. The various components recognize the voltage being pulled to ground as an indication of vehicle speed.

The primary function of the driver is to supply the ground for the component being controlled. Each driver has a fault line which is monitored by the PCM. When the PCM is commanding a component ON, the voltage of the control circuit should be low (near 0 volts). When the PCM is commanding the control circuit to a component OFF, the voltage potential of the circuit should be high (near battery voltage). If the fault detection circuit senses a voltage other than what is expected, the fault line status will change causing the DTC to set.

CONDITIONS FOR SETTING THE DTC

^ Engine speed greater than 600 RPM.

^ The PCM detects that the commanded state of the driver and the actual state of the control circuit do not match.

^ Condition must be present for a minimum of 25.5 seconds.

ACTION TAKEN WHEN THE DTC SETS

^ The DTC will be stored in the PCM memory when the diagnostic runs and fails.

^ The Malfunction Indicator Lamp (MIL) will not illuminate.

^ The PCM will record operating conditions at the time the diagnostic fails. This information will be stored in Failure Records.

CONDITIONS FOR CLEARING THE MIL/DTC

^ A history DTC will clear after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic.

^ A last test failed (Current DTC) will clear when the diagnostic runs and does not fail.

^ PCM battery voltage is interrupted.

^ Using a scan tool.

DIAGNOSTIC AIDS

Using Freeze Frame and/or Failure Records data may aid in locating an intermittent condition. If the DTC cannot be duplicated, the information included in the Freeze Frame and/or Failure Records data can be useful in determining how many miles since the DTC set. The Fail Counter and Pass Counter can also be used to determine how many ignition cycles the diagnostic reported a pass and/or a fail. Operate vehicle within the same freeze frame conditions (RPM, load, vehicle speed, temperature etc.) that were noted. This will isolate when the DTC failed. For intermittents, refer to Symptoms. Testing and Inspection

TEST DESCRIPTION

Number(s) below refer to step numbers on the diagnostic table.

3. Further circuit diagnosis may require I/P removal. The circuit from the PCM to the speedometer must be checked for being open, shorted to ground or voltage. If no trouble is found, follow the appropriate I/P diagnostic procedure.