Circuit Description
The transmission range (TR) switch is part of the park/neutral position and back-up lamp switch assembly and is externally mounted on the transmission manual shaft. The TR switch is a multi-signal switch. The PCM supplies ignition voltage to the TR switch on four signal circuits (A, B, C, and P). Each gear selector lever position grounds one or more of the switch circuits. In order to determine the gear range selected by the driver, the PCM compares the voltage combinations on the signal circuits to a look up table stored in the PCM memory.
The PCM detects the selected gear range by the state change of the switch input. Refer to Transmission Range Switch Logic .
The switch input to the PCM is represented on the Scan Tool as HI and LOW. HI indicates an ignition voltage signal. LOW indicates a zero voltage signal. The four parameters represent transmission range switch signal A, B, C and Parity.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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If the Scan Tool display indicates the proper range positions in this step, a condition exists between the underhood accessory wiring junction block and the instrument cluster.
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By disconnecting the transmission range switch, the ground path of all TR switch circuits would be removed and the PCM would recognize all circuits as open. The Scan Tool will display HI for all range signals.
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This step tests the TR switch wiring for an open or the lack of the signal voltage from the PCM.
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This step tests the TR switch wiring and the PCM by providing a ground path through a fused jumper wire. When grounded, the Scan Tool range signal A should change to LOW.
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This step tests the TR switch wiring and the PCM by providing a ground path through a fused jumper wire. When grounded, the Scan Tool range signal B should change to LOW. If other circuits also indicate LOW, they are shorted together.
Step | Action | Value(s) | Yes | No | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
1 |
Does the range selector display match each range position? | -- | Go to Intermittent Conditions (3.1 L) or Intermittent Conditions (3.8 L) in Engine Controls | |||||||||||
2 |
Does the Scan Tool TR Sw. display match each range position? | -- | ||||||||||||
Does the Scan Tool TR Sw. display match each range position? | -- | |||||||||||||
4 |
Refer to the following procedures: Did you find and correct a condition? | -- | ||||||||||||
With the Scan Tool , observe the TR Sw. A/B/C/P display. Does the Scan Tool TR Sw. A/B/C/P parameter indicate HI for all range signals in all range positions? | -- | |||||||||||||
Does the Scan Tool TR Sw. A/B/C/P parameter indicate HI for all range signals in all range positions? | -- | |||||||||||||
Does the voltage measure within the specified value at all four terminals? | 10-12 V | |||||||||||||
Connect a fused jumper wire from terminal D of the TR switch 4-way connector (signal A circuit) to ground while monitoring the Scan Tool TR Sw. A/B/C/P parameter. When the signal A circuit (CKT 771) is grounded, do any other signal circuits indicate LOW? | -- | |||||||||||||
9 | Connect a fused jumper wire from terminal B of the TR switch 4-way connector (signal B circuit) to ground while monitoring the Scan Tool TR Sw. A/B/C/P parameter. When the signal B circuit (CKT 772) is grounded, do any other signal circuits indicate LOW? | -- | ||||||||||||
10 | Connect a fused jumper wire from terminal C of the TR switch 4-way connector (signal C circuit) to ground while monitoring the Scan Tool TR Sw. A/B/C/P parameter. When the signal C circuit (CKT 773) is grounded, do any other signal circuits indicate LOW? | -- | ||||||||||||
11 | Test the signal circuits (CKTs 771, 772, 773 and 776) of the TR switch that did not indicate HI 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 signal circuits (CKTs 771, 772, 773 and 776) of the TR switch that did not indicate proper voltage for an open between the PCM and the TR switch. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | ||||||||||||
13 | Test the affected signal circuits of the TR switch for a shorted together condition between the PCM and the TR switch. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | ||||||||||||
14 | Test the ground circuit (CKT 1050) of the TR switch for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | ||||||||||||
15 | Test the signal circuits (CKTs 771, 772, 773 and 776) of the TR switch for an open between the underhood accessory wiring junction block and the instrument cluster. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | ||||||||||||
16 |
Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | ||||||||||||
17 | Refer to Diagnostic System Check - Instrument Cluster in Instrument Panel, Gauges, and Console. | -- | -- | |||||||||||
18 | Replace the TR switch (this switch is part of the park/neutral position (PNP) switch). Refer to Park/Neutral Position Switch Replacement . Did you complete the replacement? | -- | -- | |||||||||||
19 | Replace the PCM. Refer to Powertrain Control Module Replacement (3.1 L) or Powertrain Control Module Replacement (3.8 L) in Engine Controls. Did you complete the replacement? | -- | -- | |||||||||||
20 | Perform the following procedure in order to verify the repair:
Does the range selector display match each range position? | -- | System OK |
