Circuit Description
The transmission manual shift shaft switch assembly is a sliding contact switch attached to the control valve body within the transmission. The 4 inputs to the transmission control module (TCM) from the switch indicate the transmission selector lever position. This information is used for engine controls as well as determining the transmission shift patterns. The input voltage at the TCM is high when the switch is open and low when the switch is closed to ground. The state of each input is displayed on the scan tool as IMS. The IMS input parameters represented are transmission range Signal A , Signal B, Signal C and Signal P.
If the TCM detects an invalid switch state while the engine is being started, then DTC P1915 sets. DTC P1915 is a type B DTC.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P1915 Internal Mode Switch Does Not Indicate Park/Neutral (P/N) During Start
Conditions for Running the DTC
| • | The engine speed is greater than 500 RPM. |
| • | A CRANK request signal has been requested for 409 seconds (7 minutes) or greater. |
Conditions for Setting the DTC
The IMS does not indicate PARK or NEUTRAL for 2 seconds or greater when attempting to start the vehicle.
Action Taken When the DTC Sets
| • | The TCM requests the engine control module (ECM) to illuminate the malfunction indicator lamp (MIL) during the second consecutive trip in which the Conditions for Setting the DTC are met. |
| • | The TCM commands maximum line pressure. |
| • | The TCM commands an alternate coast shift pattern where downshifts occur at higher vehicle speeds while coasting. |
| • | The TCM freezes transmission adaptive functions. |
| • | The TCM disables the touch activated power (TAP) shift operation. |
| • | The TCM assumes a D4 shift pattern. |
| • | At the time of the first failure, the TCM records the operating conditions when the Conditions for Setting the DTC are met. The TCM stores this information as a Failure Record. |
| • | At the time of the second failure, the ECM records the operating conditions when the Conditions for Setting the DTC are met. The ECM stores this information as a Freeze Frame. |
| • | The TCM stores DTC P1915 in TCM history. |
Conditions for Clearing the DTC
| • | The ECM turns OFF the MIL after the third consecutive drive trip in which the TCM does not send a MIL illumination request. |
| • | A scan tool can clear the DTC. |
| • | The TCM clears the DTC from TCM history if the vehicle completes 40 warm-up cycles without a non-emission related diagnostic fault occurring. |
| • | The TCM cancels the DTC default actions when the ignition is OFF long enough in order to power down the TCM. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
All HI values, in PARK and DRIVE 4, indicate the ground circuit is OPEN.
-
With the transmission 20-way connector disconnected, all IMS values should indicate HI.
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If 1 circuit affects the other, this indicates a short between the 2 circuits.
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This step tests the internal transmission harness. If no condition is found in the harness, the condition is in the switch.
Step | Action | Values | Yes | No | ||||
|---|---|---|---|---|---|---|---|---|
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | |||||
2 |
Important:
Does each range selected match the scan tool IMS range display? | -- | Go to Testing for Intermittent Conditions and Poor Connections | Go to Step 3 | ||||
Does the scan tool IMS A/B/C/P display indicate the specified value for each range? | HI/HI/HI/HI | Go to Step 14 | Go to Step 4 | |||||
4 |
Did the linkage require adjustment? | -- | Go to Step 19 | Go to Step 5 | ||||
Does the scan tool IMS A/B/C/P display all HI? | -- | Go to Step 6 | Go to Step 10 | |||||
6 |
Did you measure ignition voltage at all 4 terminals? | -- | Go to Step 7 | Go to Step 11 | ||||
Install a fused jumper wire from the transmission range signal A circuit of the J 44152 to ground while monitoring the scan tool IMS A/B/C/P display. Refer to Automatic Transmission Inline 20-Way Connector End View . When transmission range signal A circuit is grounded, do any other circuits indicate LOW? | -- | Go to Step 12 | Go to Step 8 | |||||
8 | Install a fused jumper wire from the transmission range signal B circuit of the J 44152 to ground while monitoring the scan tool IMS A/B/C/P display. Refer to Automatic Transmission Inline 20-Way Connector End View . When transmission range signal B circuit is grounded, do any other circuits indicate LOW? | -- | Go to Step 12 | Go to Step 9 | ||||
9 | Install a fused jumper wire from the transmission range signal C circuit of the J 44152 to ground while monitoring the scan tool IMS A/B/C/P display. Refer to Automatic Transmission Inline 20-Way Connector End View . When transmission range signal C circuit is grounded, do any other circuits indicate LOW? | -- | Go to Step 12 | Go to Step 13 | ||||
10 | Test the transmission range signal circuits of the transmission manual shift shaft switch assembly that did not indicate HI for a short to ground between the TCM connector and the automatic transmission inline 20-way connector. Refer to Testing for Short to Ground and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 19 | Go to Step 18 | ||||
11 | Test the transmission range signal circuits of the transmission manual shift shaft switch assembly that did not indicate ignition voltage for an open between the TCM and the automatic transmission inline 20-way connector. Refer to Testing for Continuity and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 19 | Go to Step 18 | ||||
12 | Test the affected signal circuits of the transmission manual shift shaft switch assembly for a shorted together condition between the TCM connector and the automatic transmission inline 20-way connector. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 19 | Go to Step 18 | ||||
Test the transmission range signal circuits of the transmission manual shift shaft switch assembly for an open or shorted condition between the automatic transmission inline 20-way connector and the switch. Refer to Testing for Continuity . Did you find the condition? | -- | Go to Step 16 | Go to Step 17 | |||||
14 | Test the ground circuit of the transmission manual shift shaft switch assembly for an open between the automatic transmission inline 20-way connector and the chassis. Refer to Testing for Continuity and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 19 | Go to Step 15 | ||||
15 | Test the ground circuit of the transmission manual shift shaft switch assembly for an open between the automatic transmission inline 20-way connector and the switch. Refer to Testing for Continuity . Did you find the condition? | -- | Go to Step 16 | Go to Step 17 | ||||
16 | Replace the automatic transmission wiring harness assembly. Refer to Wiring Harness Replacement . Did you complete the replacement? | -- | Go to Step 19 | -- | ||||
17 | Replace the transmission manual shift shaft switch assembly. Refer to Transmission Control Replacement . Did you complete the replacement? | -- | Go to Step 19 | -- | ||||
18 | Replace the TCM. Refer to Control Module References for replacement, setup and programming. Did you complete the replacement? | -- | Go to Step 19 | -- | ||||
19 | Perform the following procedure in order to verify the repair:
Has the test run and passed? | -- | Go to Step 20 | Go to Step 2 | ||||
20 | 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? | -- | System OK |
