DTC P0804 Skip Shift Lamp Control Circuit


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Circuit Description

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

Conditions for Setting the DTC

Action Taken When the DTC Sets

Conditions for Clearing the DTC

Diagnostic Aids

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 .

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. Listen for an audible click when the solenoid operates. Command both the ON and the OFF states. Repeat the commands as necessary.
  1. If you do not find any trouble in the control circuit or the connection at the PCM, the PCM may be faulty. However, this is an extremely unlikely failure.
  1. The repair is not complete if the scan tool indicates that the diagnostic ran and failed.

Step

Action

Value(s)

Yes

No

1

Did you perform the Powertrain On-Board Diagnostic (OBD) System Check?

--

Go to Step 2

Go to A Powertrain On Board Diagnostic (OBD) System Check

2

Important

If the I/P is completely inoperative, refer to Instrument Cluster System Check in Instrument Panel, Gauges and Console for further diagnosis.

  1. Turn ON the ignition leaving the engine OFF.
  2. Command the shift lamp ON and OFF using the scan tool.

Does the shift lamp turn ON and OFF when commanded?

--

Go to Diagnostic Aids

Go to Step 3

3

  1. Turn OFF the ignition.
  2. Disconnect the PCM connector C2 located on the opposite side of the manufacturer's logo. Refer to PCM Replacement/Programming .
  3. Turn ON the ignition leaving the engine OFF.

Is the shift lamp OFF?

--

Go to Step 4

Go to Step 5

4

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?

--

Go to Step 6

Go to Step 7

5

Repair the short to ground in the shift lamp control circuit. Refer to Wiring Repairs in Wiring Systems. Is the repair complete?

--

Go to Step 9

--

6

  1. Inspect for poor connections at the PCM. Refer to Intermittents and Poor Connections Diagnosis in Wiring Systems.
  2. If you find a poor connection repair as necessary. Reefer to Repairing Connector Terminals in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 9

Go to Step 8

7

Test for the following conditions:

  • Faulty shift lamp indicator
  • Open ignition feed to the shift lamp indicator
  • Control circuit open or shorted to B+

Refer to Wiring Repairs in Wiring Systems. Is the repair complete?

--

Go to Step 9

--

8

Important:

Program the replacement PCM. Refer to PCM Replacement/Programming .

Replace the PCM. Is the action complete?

--

Go to Step 9

--

9

  1. Select the Diagnostic Trouble Code (DTC) option and the Clear DTC option using the scan tool.
  2. Idle the engine at the normal operating temperature.
  3. Select the Diagnostic Trouble Code (DTC) option and the Specific DTC option, then enter the DTC number using the scan tool.
  4. Operate vehicle within the Conditions for Running the DTC as specified in the supporting text, if applicable.

Does the scan tool indicate that this test passed?

--

Go to Step 10

Go to Step 2

10

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