Second Gear Start Switch/Indicator Always On or Inoperative 3.8L only
Circuit Description
The 2nd gear start switch enables the operator to select a 2nd gear start for increased traction in slippery driving conditions. When the operator selects a 2nd gear start, the 2nd gear start switch input signal momentarily toggles to zero volts. The PCM then turns ON the 2nd gear start indicator lamp and de-energizes the 1-2 shift solenoid valve, enabling second gear. The 2nd gear start indicator lamp is located within the 2nd gear start switch.
During light and medium acceleration conditions, the vehicle starts in 2nd gear when the 2nd gear start is selected. However, 2nd gear starts are overridden and 1st gear starts occur if a hard acceleration condition (wide open throttle) is requested. A normal 1st gear start is obtained by toggling the 2nd gear start switch again, or when the ignition switch is cycled OFF, then ON.
Diagnostic Aids
If the electrical circuit checks are OK and 2nd gear starts are not correct, then a mechanical/hydraulic malfunction may exist.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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This step tests the second gear start switch circuits.
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This step tests for a voltage input from the PCM to the 2nd gear start switch.
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This step tests for a faulty 2nd gear start switch.
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This step tests for a voltage input from the fuse to the 2nd gear start switch.
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This step tests for a faulty indicator lamp circuit within the 2nd gear start switch.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
Does Yes display when the switch is first pressed, and then No when the switch is pressed again? | -- | |||
Does the voltage measure within the specified value? | 10-12 V | |||
Does the Scan Tool status change between YES and NO? | -- | |||
4 | Test the ground circuit (CKT 451) of the 2nd gear start switch for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | ||
5 | Test the signal circuit (CKT 1571) of the 2nd gear start switch for an open or short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | ||
6 | Does the 2nd gear start indicator lamp illuminate when the switch is first pressed, and then turn Off when the switch is pressed a second time? | -- | System OK | |
7 | Does the lamp illuminate at all times? | -- | ||
Install a test lamp to ground and probe terminal B of the second gear start switch connector. Does the test lamp illuminate? | -- | |||
Install a test lamp to ground and probe terminal A of the second gear start switch connector. Does the test lamp illuminate? | -- | |||
10 |
Is the fuse open? | -- | ||
11 | Test the power feed circuit (CKT 39) of the 2nd gear start switch for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | -- | |
12 | Test the power feed circuit (CKT 39) of the 2nd gear start switch for an open condition. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | -- | |
13 | Test the control circuit (CKT 1572) of the 2nd gear start switch for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | ||
14 | Test the control circuit (CKT 1572) of the 2nd gear start switch for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | ||
15 | Replace the 2nd gear start switch. Did you complete the replacement? | -- | -- | |
16 | Replace the PCM. Refer to Powertrain Control Module Replacement/Programming in Engine Controls. Did you complete the replacement? | -- | -- | |
17 | After the repair is complete, observe 2nd Gear Start on the Scan Tool display, while pressing the 2nd gear start switch. Does Yes display when the switch is first pressed, and then No when the switch is pressed again? And, does the 2nd gear start switch indicator lamp turn On after the second gear start switch is first pressed, and then turn Off after the 2nd gear start switch is pressed again? | -- | System OK |
