DTC P0804 Skip Shift Lamp Control
Circuit
An ignition voltage is
supplied to the Skip Shift Lamp. The PCM controls the lamp by grounding the
control circuit via an internal switch called a driver. 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.
- Ignition voltage greater than 6.0
volts but less than 16 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.
- All conditions exist 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 the 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 determines 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.
If the I/P is completely
inoperative, refer to Instrument
Cluster System Check in Instrument Panel, Gauges and Console for further
diagnosis.
For an intermittent,
refer to Symptoms
.
The numbers below refer
to the step numbers on the diagnostic table.
|
Step |
Action |
Value(s) |
Yes |
No |
|
Did
you perform the Powertrain On-Board Diagnostic
(OBD) System Check? |
-- |
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|
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 shift lamp turn ON and OFF when commanded? |
-- |
Go to Diagnostic Aids |
||
Is
the shift lamp OFF? |
-- |
|||
|
Probe
the shift lamp control circuit in the PCM harness connector with a fused
jumper wire connected to ground. Refer to Probing
Electrical Connectors in Wiring Systems. Is the shift lamp ON? |
-- |
|||
|
Repair
the short to ground in the shift lamp control circuit. Refer to Wiring
Repairs in Wiring Systems. Is the repair complete? |
-- |
-- |
||
Did
you find and correct the condition? |
-- |
|||
|
Test
for the following conditions:
Refer
to Wiring
Repairs in Wiring Systems. Is the repair complete? |
-- |
-- |
||
|
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 |