Test Description
WARNING: This page is about a different car, the 2004 Pontiac Vibe. However, it is still accessible from the selected car via links, so may be relevant.
The numbers below refer to the step numbers on the diagnostic table.
- 1: The Powertrain OBD System Check prompts the technician to complete some basic checks and store the freeze frame data on the scan tool if applicable. This creates an electronic copy of the data taken when the fault occurred. The information is then stored in the scan tool for later reference.
- 2: This step checks the L position signal circuit.
- 3: This step checks the N and the P position signal circuit.
- 4: This step checks the P position signal circuit.
- 5: This step checks the R position signal circuit.
- 6: This step checks for poor terminal contact at the PCM.
- 7: This step checks for a faulty PCM.
- 8: This step checks for a short to voltage in the L position.
- 9: This step checks for a short to ground in the L position.
- 10: This step checks for an open in the L position.
- 12: This step checks for a short to voltage in the N and P positions.
- 13: This step checks for a short to ground in N and P positions.
- 14: This step checks for an open in N and P positions.
- 15: This step checks for a short to voltage in the 2 position.
- 16: This step checks for a short to ground in the 2 position.
- 17: This step checks for an open in the 2 position.
- 18: This step checks for a short to voltage in R position.
- 19: This step checks for a short to ground in R position.
- 20: This step checks for an open in R position.
DTC P1780
| Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
| Schematic Reference: Automatic Transmission Controls Schematics | ||||
| 1 | Was the On-Board Diagnostic (OBD) System Check performed? | - | Go to Step 2 | Go to Diagnostic System Check - Engine Controls in Engine Controls |
| 2 |
|
- | Go to the applicable DTC table | Go to Step 3 |
| 3 |
|
10-14 V in Low gear 0-2 V in all other gears |
Go to Step 5 | Go to Step 10 |
| 4 | Using J 39200
measure voltage between ground and the PCM harness connector C3, terminal 11 while shifting the manual selector from Low to Neutral gear and Park gear. Is the voltage within the range specified? |
10-14 V in Neutral and Park gears | Go to Step 5 | Go to Step 13 |
| 5 | Using J 39200
measure the voltage between ground and the PCM harness connector C3, terminal 9 while shifting the manual selector from Park to Second gear. Is the voltage within the range specified? |
10-14 V in Second gear | Go to Step 6 | Go to Step 16 |
| 6 | Using J 39200
measure the voltage between ground and the PCM harness connector C3, terminal 11 while shifting the manual selector from Second to Reverse gear. Is the voltage within the range specified? |
10-14 V in Reverse gear | Go to Step 7 | Go to Step 19 |
| 7 | Inspect the PCM harness connector C3 for poor terminal contact. Is poor terminal evident? |
- | Go to Step 23 | Go to Step 8 |
| 8 |
|
- | Go to Step 24 | Go to Step 22 |
| 9 |
|
1-2 V | Go to Step 10 | Go to Step 27 |
| 10 | Using J 39200
measure the resistance between ground and the PCM harness connector C3, terminal 19. Is the resistance equal to the value specified? |
infinity | Go to Step 11 | Go to Step 28 |
| 11 | Using J 39200
measure the resistance between PCM harness connector C3, terminal 19 and the PNP switch connector terminal 6 - harness side. Is the resistance less than the range specified? |
2 Ω | Go to Step 12 | Go to Step 29 |
| 12 | Using J 39200
measure the voltage between ground and PNP switch connector terminal 4 - harness side. Is the voltage within the range specified? |
10-14 V | Go to Step 25 | Go to Step 26 |
| 13 |
|
1-2 V | Go to Step 14 | Go to Step 30 |
| 14 | Using J 39200
measure the resistance between ground and the PCM harness connector C3, terminal 11. Is the resistance equal to the specified value? |
infinity | Go to Step 15 | Go to Step 31 |
| 15 | Using J 39200
measure the resistance between the PCM harness connector C3, terminal 11 and the PNP switch connector terminal 3 - harness side. Is the voltage equal to the specified value? |
2 Ω | Go to Step 12 | Go to Step 32 |
| 16 |
|
1-2 V | Go to Step 17 | Go to Step 33 |
| 17 | Using J 39200
measure the resistance between ground and PCM harness connector C3, terminal 18. Is the resistance equal to the value specified? |
infinity | Go to Step 18 | Go to Step 34 |
| 18 | Using J 39200
measure the resistance between the PCM harness connector C3, terminal 18 and the PNP switch connector terminal 5 - harness side. Is the resistance less than the value specified? |
2 Ω | Go to Step 12 | Go to Step 35 |
| 19 |
|
1-2 V | Go to Step 20 | Go to Step 36 |
| 20 | Using J 39200
measure the resistance between ground and the PCM harness connector C3, terminal 17 Is the resistance equal to the value specified? |
infinity | Go to Step 21 | Go to Step 37 |
| 21 | Using J 39200
measure the resistance between the PCM harness connector C3, terminal 17 and the PNP switch connector terminal 8 - harness side. Is the resistance less than the value specified? |
2 Ω | Go to Step 12 | Go to Step 38 |
| 22 | Refer to Diagnostic Aids for a possible intermittent condition. If OK, replace the PCM. Refer to Powertrain Control Module (PCM) Replacement
in Engine Controls. Is the action complete? |
- | Go to Step 39 | - |
| 23 | Repair the terminal that exhibits poor contact. Is the action complete? |
- | Go to Step 39 | - |
| 24 | Refer to Diagnostic Aids for additional information regarding this DTC. Is the action complete? |
- | Go to Step 39 | - |
| 25 |
|
- | Go to Step 39 | - |
| 26 | Repair the open or high resistance in RED/BLU wire between the PNP switch and GAGE fuse. Refer to Testing for Intermittent Conditions and Poor Connections
in Wiring Systems. Is the action complete? |
- | Go to Step 39 | - |
| 27 | Repair the short to voltage in LT GRN wire between the PNP switch and the PCM. Is the action complete? |
- | Go to Step 39 | - |
| 28 | Repair the short to ground in LT GRN wire between the PNP switch and the PCM. Is the action complete? |
- | Go to Step 39 | - |
| 29 | Repair the open or high resistance in LT GRN wire between the PNP switch and the PCM. Is the action complete? |
- | Go to Step 39 | - |
| 30 | Repair the short to voltage in BLK/WHT wire between the PNP switch and the PCM. Is the action complete? |
- | Go to Step 39 | - |
| 31 | Repair the short to ground in BLK/WHT wire between PNP switch and the PCM. Is the action complete? |
- | Go to Step 39 | - |
| 32 | Repair the open or high resistance in BLK/WHT wire between PNP switch and the PCM. Is the action complete? |
- | Go to Step 39 | - |
| 33 | Repair the short to voltage in LT GRN/RED wire between the PNP switch and the PCM. Is the action complete? |
- | Go to Step 39 | - |
| 34 | Repair the short to ground in LT GRN/RED wire between the PNP switch and the PCM. Is the action complete? |
- | Go to Step 39 | - |
| 35 | Repair the open and high resistance in LT GRN/RED wire between the PNP switch and the PCM. Is the action complete? |
- | Go to Step 39 | - |
| 36 | Repair the short to voltage in RED/BLK wire between the PNP switch and the PCM. Is the action complete? |
- | Go to Step 39 | - |
| 37 | Repair the short to ground in RED/BLK wire between the PNP switch and the PCM. Is the action complete? |
- | Go to Step 39 | - |
| 38 | Repair the open or high resistance in RED/BLK wire between the PNP switch and the PCM. Is the action complete? |
- | Go to Step 39 | - |
| 39 |
|
- | Go to Applicable DTC Table | System OK |