DTC P0608 Vehicle Speed Output
Circuit
Various components apply
a voltage to the Vehicle Speed Output circuit. 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 VSS signal input.
The various components recognize the voltage being pulled to ground as an
indication of vehicle speed.
The driver supplies the
ground for the component being controlled. Each driver has a fault line which
the PCM monitors. When the PCM commands a component ON, the voltage of the
control circuit should be low (near 0 volts). When the PCM commands 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 changes causing the DTC to
set.
Conditions
for Running the DTC
- The engine speed is greater than
600 RPM.
- The ignition voltage is between 6.0
volts and 16.0 volts.
Conditions
for Setting the DTC
- The PCM detects that the commanded
state of the driver and the actual state of the control circuit do not
match.
- The condition must be present for a
minimum of 10 seconds.
Action
Taken When the DTC Sets
- The PCM stores the DTC information
into memory when the diagnostic runs and fails.
- The malfunction indicator lamp (MIL)
will not illuminate.
- The PCM records the operating
conditions at the time the diagnostic fails. The PCM stores this
information in the Failure Records.
Conditions
for Clearing the DTC
- A last test failed, or current DTC,
clears when the diagnostic runs and does not fail.
- 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.
- Use a scan tool in order to clear
the DTC.
Using Freeze Frame
and/or Failure Records data may aid in locating an intermittent condition. If
you cannot duplicate the DTC, the information included in the Freeze Frame
and/or Failure Records data can aid in determining how many miles since the DTC
set. The Fail Counter and Pass Counter can also aid determining how many
ignition cycles the diagnostic reported a pass and/or a fail. Operate the
vehicle within the same freeze frame conditions (RPM, load, vehicle speed,
temperature etc.) that you observed. This will isolate when the DTC failed.
For an intermittent,
refer to Symptoms
.
The numbers below refer
to the step numbers on the diagnostic table.
- Further circuit
diagnosis may require I/P
removal. The circuit from the PCM to the speedometer must be tested for
being open, shorted to ground or, voltage. If you do not find any trouble,
follow the appropriate I/P diagnostic procedure.
|
DTC P0608 - Vehicle Speed Sensor (VSS) Output Circuit Step |
Action |
Value(s) |
Yes |
No |
|
Did
you perform the Powertrain On-Board Diagnostic
(OBD) System Check? |
-- |
|||
|
Important If the I/P is completely
inoperative, refer to Instrument
Cluster System Check in Instrument Panel, Gauges and Console for further
diagnosis.
Does
the vehicles speedometer indicate vehicle speed? |
-- |
Go to Diagnostic Aids |
||
Does
the DMM display above the specified value? |
9.6V |
|||
Does
the DMM display continuity? |
-- |
|||
Did
you find and correct the condition? |
-- |
Go to Instrument
Cluster System Check in Instrument Panel, Gauges and Console. |
||
|
Repair
the open vehicle speed output circuit. Refer to Wiring
Repairs in Wiring Systems. Is the action complete? |
-- |
-- |
||
Did
you find and correct the condition? |
-- |
|||
|
Important: Program the replacement
PCM. Refer to PCM
Replacement/Programming . Replace
the PCM. Is the action complete? |
-- |
-- |
||
Does
the scan tool indicate that this test passed? |
-- |
|||
|
Select
the Capture Info option and the Review Info option using the scan tool. Does
the scan tool display any DTCs that you have not diagnosed? |
-- |
Go to the applicable
DTC table |
System OK |