Circuit Description
With the ignition ON battery voltage is supplied to the skip shift lamp through the instrument panel cluster (IPC). The powertrain control module turns on the skip shift lamp at the same time the skip shift solenoid is enabled. The powertrain control module (PCM) controls the skip shift 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 internal fault detection circuit senses a voltage other than what is expected, the fault line status changes, causing DTC P0804 to set. DTC P0804 is a type C DTC.
Conditions for Enabling the Skip Shift Solenoid and Lamp
| • | The vehicle speed is between 24-31 km/h (15-19 mph). |
| • | The engine coolant temperature (ECT) is greater than 77°C (171°F). |
| • | The BARO is greater than 76 kPa. |
| • | The accelerator pedal position (APP) is less than 26 percent. |
| • | Once the 1-4 Upshift solenoid is enabled the solenoid will not be re-enabled until the vehicle speed returns to 0 km/h (0 mph) and the conditions for enabling the 1-4 Upshift solenoid are met. |
Conditions for Running the DTC
The engine is running.
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. |
| • | Condition must exist for a minimum of 5 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 and 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 the scan tool in order to clear the DTC. |
Diagnostic Aids
| • | Remove any debris from the PCM connector surfaces before servicing the PCM. Inspect the PCM connector gaskets when diagnosing/replacing the PCM. Ensure that the gaskets are installed correctly. The gaskets prevent contaminate intrusion into the PCM. |
| • | For any test that requires probing the PCM or a component harness connector, use the J 35616 connector test adapter kit. Using this kit prevents damage to the harness/component terminals. Refer to Using Connector Test Adapters in Wiring Systems. |
| • | Low system voltage can cause this DTC to set. When reviewing captured data, verify if a low system voltage condition was present at the time the DTC was stored in memory. |
| • | For an intermittent condition, refer to Testing for Intermittent Conditions and Poor Connections . |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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Watch for the skip shift lamp to illuminate. Command both the ON and OFF states. Repeat the commands as necessary.
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Verifies that the powertrain control module (PCM) is providing ground to the skip shift lamp .
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Tests if ground is constantly being applied to the skip shift lamp .
Step | Action | Yes | No |
|---|---|---|---|
1 | Did you perform the Diagnostic System Check - Engine Controls? | Go to Step 2 | Go to Diagnostic System Check - Engine Controls in Engine Controls - 5.7L |
Does the skip shift lamp turn ON and OFF? | Go to Step 3 | Go to Step 4 | |
3 |
Does the DTC fail this ignition? | Go to Step 4 | Go to Testing for Intermittent Conditions and Poor Connections Wiring Systems |
4 |
Does the test lamp illuminate? | Go to Step 5 | Go to Step 11 |
Does the test lamp turn ON and OFF? | Go to Step 9 | Go to Step 6 | |
Does the test lamp remain illuminated with each command? | Go to Step 8 | Go to Step 7 | |
7 | Test the control circuit of the skip shift lamp for a short to voltage or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 14 | Go to Step 10 |
8 | Test the control circuit of the skip shift lamp for a short to ground. Refer to Testing for Short to Ground and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 14 | Go to Step 10 |
9 | Inspect for poor connections at the skip shift lamp . Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 14 | Go to Step 12 |
10 | Inspect for poor connections at the harness connector of the powertrain control module (PCM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 14 | Go to Step 13 |
11 | Repair the ignition 1 voltage circuit of the skip shift lamp. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 14 | -- |
12 | Replace the skip shift lamp . Refer to Instrument Cluster Indicator Lamp Replacement in Instrument Cluster, Gauges and Console. Did you complete the replacement? | Go to Step 14 | -- |
13 | Replace the powertrain control module (PCM). Refer to Powertrain Control Module Replacement in Engine Controls. Did you complete the replacement? | Go to Step 14 | -- |
14 | Perform the following procedure in order to verify the repair:
Has the test run and passed? | Go to Step 15 | Go to Step 2 |
15 | With the scan tool, observe the stored information, capture info and DTC info. Does the scan tool display any DTCs that you have not diagnosed? | Go to Diagnostic Trouble Code (DTC) List in Engine Controls - 5.7L | System OK |
