| Table 1: | Transaxle Range Switch Valid Input Combinations |
Circuit Description
This vehicle uses an electronic gear indicator display. There are four inputs which are switches to ground that each have a unique switch pattern. All four of these inputs are housed in the PNP switch and operate together as the Transaxle Range Switch. The PCM uses the combination of the switch patterns to determine the gear selected by the driver. This information is then sent by serial data to the IPC for gear indicator display. When the Conditions for Running the DTC are true this test compares the gear indicated by the Transaxle Range Switch to the gear selected from the Transmission Fluid Pressure Manual Valve Position Switch (TFP switch). If the gear indicated is not the same for both, this DTC is set.
Conditions for Running the DTC
| • | Engine running continously for 5 seconds. |
| • | Ignition voltage is between 10 and 16 volts. |
| • | Transaxle Range switch does not indicate an illegal position. |
| • | Transmission Fluid Pressure Manual Valve Position Switch (TFP switch) does not indicate an illegal position. |
| • | DTC P1810 has ran and passed. |
Conditions for Setting the DTC
The Transaxle Range switch and the Transmission Fluid Pressure Manual Valve Position Switch (TFP switch) indicate different gears for at least 7.8 seconds.
Action Taken When the DTC Sets
| • | The Malfunction Indicator Lamp (MIL) will not illuminate. |
| • | No message will be displayed. |
Conditions for Clearing the MIL/DTC
| • | A History DTC will clear after forty consecutive warm-up cycles with no failures of any non-emission related diagnostic test. |
| • | A Last Test Failed (current) DTC will clear when the diagnostic runs and does not fail. |
| • | Use a scan tool to clear DTCs. |
| • | Interrupting PCM battery voltage may or may not clear DTCs. This practice is not recommended. Refer to Clearing Diagnostic Trouble Codes in PCM Description and Operation. |
Diagnostic Aids
| • | The modes (circuits) are displayed in order A/B/C/P. |
| • | L indicates the circuit low (switched / shorted to ground). |
| • | H indicates the circuit is high (open). |
Gear Selector Position | Scan Tool "Trans Range ABCP" Display | |||
|---|---|---|---|---|
A | B | C | P | |
Park (P) | L | H | H | L |
Reverse (R) | L | L | H | H |
Neutral (N) | H | L | H | L |
Drive 4 (OD) | H | L | L | H |
Drive 3 (3) | L | L | L | L |
Drive 2 (2) | L | H | L | H |
Low (1) | H | H | L | L |
| • | If the DTC sets and the PRNDL on the IPC is flashing while driving or when the driver in not moving the gear selector lever, record the transaxle range switch input and compare the values to the table. For example, if the vehicle was operating in overdrive when the PRNDL on the IPC flashed and the input read High, Low, High, High, check for an intermittent open in circuit 773. |
| • | Manipulate related wiring and connectors while observing the transaxle range switch input. If an intermittent is induced, the digit corresponding to the circuit will change. |
| • | Use the Failure Records data to help determine which switch was reading incorrectly. If the DTC set and the pressure switch indicated D1 and the select lever switch indicated P/N and the engine sensors (MAP, TP, MAF etc.) appear to indicate the vehicle was in Park or Neutral then check the pressure switch/circuits for an intermittent fault. |
Depending on the Scan Tool used, the transmission fluid pressure switch parameter and the gear select lever parameter may have two different titles.For example: when using a Tech 1 on a 1996 vehicle the gear select lever parameter would be named Sel. Lever Sw. and Sel. Lever Sw. A/B/C/P. The same vehicle and parameter using a Tech 2 would be named Transmission Range and T R Switch A/B/C/P. These same parameters may also call the state of the circuit differently. For example: the Tech 1 may indicate ON for an open circuit while the Tech 2 would indicate High for an open circuit. Proper verification of the parameter being observed can be indicated by the inability of the transmission fluid pressure switch to indicate any gear other than Drive 2 when the vehicle is not running (no pressure available).
Test Description
Number(s) below refer to the step number(s) on the Diagnostic Table.
-
The adjustment procedures must be done before diagnosis of the system. This step does a comparison of both the transaxle range switch and the transaxle pressure switch (TFP switch). If both displays match in all gear selections then the fault is not present or may have been repaired when the adjustment procedures were performed.
-
The engine must be running in order to obtain gear indications from the TFP switch.
If TFP Switch doesn't match the gear selected then the transaxle pressure switches are at fault.
-
Checking if the ground circuit to the switch may be at fault.
-
If a circuit stays High or Low all the time, that circuit or switch is open or shorted to ground.
-
A few conditions could occur in the Transmission Fluid Pressure Manual Valve Position Switch and circuits which may not set a DTC P1810. Only one of these faults could be a circuit only or PCM fault.
Step | Action | Value(s) | Yes | No | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | ||||||||||
|
Important: Perform the Park/Neutral Position Switch adjustment procedure and the Shift Cable/Lever adjustment procedure in Automatic Transmission/Transaxle before proceeding with this table.
Do the scan tool displays match each other for the range that is selected? | -- | Go to Diagnostic Aids | ||||||||||
Does TFP Switch (pressure) match each range selected? | -- | |||||||||||
Do all the modes display High? | -- | |||||||||||
Do any of the modes (A / B / C / P) stay High or Low all of the time regardless of selector position? | -- | |||||||||||
6 | Do the mode(s) that did not change always display High? | -- | ||||||||||
7 |
Is the resistance on the tested CKT(s) less than the value specified? | 5 ohms | ||||||||||
8 | Repair the short to ground in the CKT(s) that have low or no resistance to ground. Is the repair complete? | -- | -- | |||||||||
9 |
Is the resistance on the tested CKT(s) more than the value specified? | 5 ohms | ||||||||||
10 | Repair the open in the CKT(s) that have high or infinite resistance. Is the repair complete? | -- | -- | |||||||||
11 |
Do all modes indicate ON (High)? | -- | ||||||||||
12 |
Does the display change from High to Low when the circuit is jumpered to ground? | -- | ||||||||||
13 |
Is the resistance the same or less than the value specified? | 5 ohms | ||||||||||
14 | Repair the open/high resistance in CKT 451. Is the repair complete? | -- | -- | |||||||||
15 |
Was a repair made? | -- | ||||||||||
16 | Replace the transaxle range switch. Is the replacement complete? | -- | -- | |||||||||
Is DTC P1810 also set? | -- | Go to DTC P1810 TFP Valve Position Switch Circuit in Automatic Transaxle. | ||||||||||
18 | With the engine running, does the TFP switch display (pressure) match in P, R, N, and D4 but not in D3, D2 and D1? | -- | ||||||||||
19 | Replace the Transmission Fluid Pressure Manual Valve Position Switch (TFP switch) assembly. Is the replacement complete? | -- | -- | |||||||||
20 | Disconnect the Transaxle 20-way connector and shift through gear range. Does the display ALWAYS indicate P/N? | -- | ||||||||||
21 | Check for a shorted to ground Transaxle Range B input circuit between the Transaxle 20-way connector and the PCM. Was a shorted condition repaired? | -- | ||||||||||
22 |
Is the repair complete? | -- | -- | |||||||||
23 |
Was a repair made? | -- | ||||||||||
24 | Replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Is the replacement complete? | -- | -- |
