DTC P0730 Incorrect Gear Ratio. Cadillac Concours 1996

For 1990-2009 cars

Table 1: | 4T80-E Range Reference, modified for use as P0730 Thumbnail
Table 2: | Gear Ratios
Table 3: | DTC P0730 Incorrect Gear Ratio

#### 4T80-E Range Reference, modified for use as P0730 Thumbnail

Range | Reverse | D4 | D3 | D2 | D1
--- | --- | --- | --- | --- | ---
Gear | R | 1st | 2nd | 3rd | 4th | 1st | 2nd | 3rd | 1st | 2nd | 1st | 2nd
1-2 Shift Solenoid | ON | ON | OFF | OFF | ON | ON | OFF | OFF | ON | OFF | ON | OFF
2-3 Shift Solenoid | OFF | OFF | OFF | ON | ON | OFF | OFF | ON | OFF | OFF | OFF | OFF
Forward | -- | A | A | A | A | A | A | A | A | A | A | A
Coast | -- | -- | -- | -- | -- | -- | -- | A | A | A | A | A
3rd Clutch | -- | -- | -- | A | A | -- | -- | A | -- | -- | -- | --
2nd Clutch | -- | -- | A | A | A | -- | A | A | -- | A | -- | A
Reverse | A | -- | -- | -- | -- | -- | -- | -- | -- | -- | -- | --
4th Band | -- | -- | -- | -- | A | -- | -- | -- | -- | A | -- | A
Lo/Rev Band | A | A | -- | -- | -- | A | -- | -- | A | -- | A | --
Lo Roller | -- | H | -- | -- | -- | H | -- | -- | H | -- | H | --
2nd Sprag | -- | -- | H | -- | -- | -- | H | -- | -- | H | -- | H
Forward Sprag | -- | H | H | H | -- | H | H | H | H | H | H | H

- A = Applied
- H = Holding
- ON = The solenoid is energized.
- OFF = The solenoid is de-energized

### Circuit Description

The Powertrain Control Module (PCM) calculates gear ratio based on data from the Automatic Transmission Input (Shaft) and Output(Shaft) Speed sensors. The PCM compares the known transmission gear ratio to a calculated ratio for each gear range selected.

DTC P0730 sets if the steady state adapts are at their maximum, and the PCM detects an incorrect gear ratio because of excessive slip within the transmission. DTC P0730 is a Type C DTC.

### Conditions for Setting the DTC

• | No MAF DTCs P0101, P0102 or P0103 are set.

• | No TP DTCs P0121, P0122 or P0123 are set.

• | No VSS DTCs P0502 or P0503 are set.

• | No A/T ISS DTCs P0716 or P0717 are set.

• | No 1-2 shift solenoid valve electrical DTC P0753 is set.

• | No 2-3 shift solenoid valve electrical DTC P0758 is set.

• | No TFP Val Position Sw. DTC P1810 is set.

• | Engine running for more than 5 seconds.

• | The vehicle speed is greater than 11 km/h (7 mph).

• | The throttle angle is greater than 15.7°.

• | The automatic transmission range switch is not indicating park or neutral.

• | At least one steady state adapt cell is at maximum.

• | The transmission fluid temperature is greater than 20°C (68°F).

• | Delivered torque is greater than 135 N·m (100 lb ft)

• | All of the following fail cases are true for 4 seconds:

- | First gear ratio is less than 2.87 or greater than 3.11.

- | Second gear ratio is less than 1.54 or greater than 1.71.

- | Third gear ratio is less than 0.95 or greater than 1.05.

- | Fourth gear ratio is less than 0.65 or greater than 0.71.

- | Reverse gear ratio is less than 2.02 or greater than 2.23.

### Action Taken When the DTC Sets

• | SERVICE TRANSMISSION displays on the Driver Information Center (DIC).

• | The PCM commands maximum line pressure.

• | The PCM disable steady state adapts.

• | The PCM disable upshift adapts.

• | The PCM disable garage shift adapts.

• | The PCM inhibits torque management.

### Conditions for Clearing the DIC/DTC

• | The PCM sees a correct gear ratio in each gear range for 4 seconds.

• | A scan tool can clear the DTC from the PCM history. The PCM clears the DTC from the PCM history if the vehicle completes 40 warm-up cycles without a failure reported.

### Diagnostic Aids

Ensure that the vehicle's final drive ratio matches PROM calibration.

Refer to Range Reference

#### Gear Ratios

Gear | Ratio
--- | ---
First | 2.96
Second | 1.63
Third | 1.00
Fourth | 0.68
Reverse | 2.13

### Test Description

The numbers below refer to the steps on the diagnostic chart.

1. This Step ensures that you performed the Powertrain On-Board Diagnostic System Check.

2. This Step verifies that you inspected the transmission fluid and that the fluid is at the proper level. An under-filled transmission could result in insufficient hydraulic line pressure causing the transmission to slip.

3. This Step inspects for additional DTCs. If a VSS or A/T ISS DTC is set, refer to those DTC charts first.

4. This Step installs the J 21867 Pressure Gauge along with the J 21867-94 Line Pressure Fitting. With the engine running (in Park), control the amount of current through the Pressure Control Solenoid Valve (PC Sol. Valve) while monitoring the pressure gauge.

5. This Step replaces the Pressure Control Solenoid Valve which caused the high line pressure.

6. This Step inspects and either replaces or repairs the faulty components that caused the low line pressure.

7. Set the scan tool in snapshot mode. Monitor the following three parameters:

   Important: When driving the vehicle in Reverse, the commanded gear will be first.

• | Automatic Transmission Fluid Pressure Manual Valve Position switch (TFP Val. Position Sw.)

• | Transmission gear ratio

• | Commanded gear

8. This Step inspects the reverse clutch and LO reverse band for slippage when the vehicle is placed in Reverse and the ratio is too high (2.22).

9. This Step inspects the valve body for hydraulic failure when the vehicle was placed in Reverse (2.02).

10. This Step instructs the technician to drive the vehicle with the gear select lever in the Overdrive range. Compare the snapshot data with the value column.

11. This Step inspects and repairs the faulty components that caused a ratio greater than 1.05.

12. This Step inspects and repairs the faulty components that caused a ratio greater than 1.71.

13. This Step inspects and repairs the faulty components that caused a ratio greater than 1.54.

14. This Step inspects and repairs the faulty components that caused a ratio greater than 2.87.

15. This Step instructs the technician to drive the vehicle with the gear select lever in the D3 range. Compare the snapshot data with the value column.

16. This Step inspects and repairs the faulty components that caused a ratio less than 0.95.

17. This Step inspects and repairs the faulty components that caused a ratio that was less than 0.95 but greater than 0.71.

18. This Step inspects and repairs the faulty components that caused a ratio greater than 1.05.

19. This Step inspects and repairs the faulty components that caused a ratio greater than 1.71.

20. This Step inspects and repairs the faulty components that caused a ratio less than 1.54.

21. This Step inspects and repairs the faulty components that caused a ratio less than 2.87.

22. This Step instructs the technician to drive the vehicle with the gear select lever in the D2 range. Compare the snapshot data with the value column.

23. This Step inspects and repairs the faulty components that caused a ratio less than 1.54.

24. This Step inspects and repairs the faulty components that caused a ratio greater than 1.05.

25. This Step inspects and repairs the faulty components that caused a ratio greater than 1.71.

26. This Step inspects and repairs the faulty components that caused a ratio less than 1.54.

27. This Step inspects and repairs the faulty components that caused a ratio less than 2.87.

28. This Step instructs the technician to drive the vehicle with the gear select lever in the D1 (low) range. Compare the snapshot data with the value column.

29. This Step inspects and repairs the faulty components that caused a ratio less than 2.87.

30. This Step inspects and repairs the faulty components that caused a ratio greater than 3.11.

31. This Step replaces the PCM after you inspect the components.

#### DTC P0730 Incorrect Gear Ratio

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 | Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | Go to Step 2 | Go to A Powertrain On Board Diagnostic (OBD) System Check
2 | Has the transmission fluid checking procedure been performed? | -- | Go to Step 3 | Go to Transmission Fluid Check

3

1. Install the scan tool (tech 1) .
2. With the engine OFF, turn the ignition switch to the RUN position.

Important: Before clearing the DTCs, use the scan tool in order to record the Failure Records for reference. The Clear Info function will erase the data.

3. Record the DTC Failure Records.

Are any of the following DTCs set: P0502, P0503, P0716, P0717, P0753, or P0758?

--

Go to Step 4

Go to Step 5

4

1. Diagnose these DTCs.
2. Repair these DTCs first.

Did you diagnose and correct the condition?

--

Go to Step 51

--

5

1. Install J 21867 Pressure Gauge and J 21867-94 Line Pressure Fitting.
2. Select output control, PC Sol. on the scan tool.
3. With the vehicle in Park and the engine running, increase and decrease the PC Sol. Valve amperage.

Refer to the Line Pressure Check .

Are the line pressure and the PC Sol. Valve amperage within the specified ranges?

0.1-1.1 A

50-220 PSI

Go to Step 10

Go to Step 6

6 | Is the line pressure higher than the specified range? | -- | Go to Step 7 | Go to Step 8
7 | Inspect and repair the Pressure Control Solenoid Valve. Refer to PC Sol. Valve Inspection/Unit Repair. Is the repair complete? | -- | Go to Step 51 | --
8 | Is the line pressure lower than the specified range? | -- | Go to Step 9 | Go to Step 10

9

Inspect and repair the following items:

1. Scavenge pump leaking at the pump body
2. Scavenge tube restriction
3. Scavenge tube seals damaged or leaking
4. Primary pump leakage at gasket or pump body
5. Clogged screens
6. Pressure relief valve stuck (sediment)
7. Secondary pump leakage at the gasket or at the pump body

Refer to unit repair.

Is the repair complete?

--

Go to Step 51

--

10

1. Select snapshot mode on the scan tool and capture the following data pairs:

• | TFP Val. Position Sw.

• | Transmission gear ratio.

• | Commanded gear.

2. Drive the vehicle in reverse.

Do the TFP Switch and the gear ratio match the specified parameters?

Range A/B/C

On On Off

Ratio greater than 2.22

Go to Step 11

Go to Step 12

11 | Inspect and repair the valve body for a hydraulic problem. Is the inspection and repair complete? | -- | Go to Step 51 | --
12 | Do the TFP Val. Position Sw. and gear ratio match the specified parameters? | Range A/B/C On On Off Ratio less than 2.02 | Go to Step 13 | Go to Step 14
13 | Inspect and repair the valve body for a hydraulic problem. Is the inspection and repair complete? | -- | Go to Step 51 | --
14 | Drive the vehicle in the OD range (ensure that 4th gear is achieved). Do the TFP Switch and the gear ratio match the specified parameters? | Range A/B/C Off On On Ratio less than 0.65 | Go to Step 15 | Go to Step 16

15

Inspect and repair the following circuits.

• | VSS circuits - DTCs P0502 & P0503

• | A/T ISS circuits - DTCs P0716 & P0717

Is the inspection and repair complete?

--

Go to Step 51

--

16 | Do the TFP Switch and the gear ratio match the specified parameters? | Range A/B/C Off On On Ratio greater than 1.05 | Go to Step 17 | Go to Step 18

17

Inspect and repair the following items.

• | The third clutch is slipping or dragging

• | The forward clutch is slipping

• | The forward sprag clutch has failed

Is the inspection and repair complete?

--

Go to Step 51

--

18 | Do the TFP Switch and the gear ratio match the specified parameters? | Range A/B/C On Off Off Ratio greater than 1.71 | Go to Step 19 | Go to Step 20

19

Inspect and repair the following items.

• | The second clutch is slipping or dragging

• | The second sprag clutch has failed

• | The forward clutch is slipping

• | The forward sprag clutch has failed

Is the inspection and repair complete?

--

Go to Step 51

--

20 | Do the TFP Switch and the gear ratio match the specified parameters? | Range A/B/C On Off Off Ratio less than 1.54 | Go to Step 21 | Go to Step 22

21

Inspect and repair the following items.

• | The third clutch is slipping or dragging

• | The forward clutch is slipping

• | The forward sprag clutch has failed

Is the inspection and repair complete?

--

Go to Step 51

--

22 | Do the TFP Switch and the gear ratio match the specified parameters? | Range A/B/C On Off Off Ratio less than 2.87 | Go to Step 23 | Go to Step 24

23

Inspect and repair the following items.

• | The second clutch is slipping or dragging

• | The second sprag clutch has failed

• | The forward clutch is slipping

• | The forward sprag clutch has failed

Is the inspection and repair complete?

--

Go to Step 51

--

24 | Drive the vehicle in the 3rd gear range (ensure that 3rd gear is achieved). Do the TFP Switch and the gear ratio match the specified parameters? | Range A/B/C On On Off Ratio less than 0.95 | Go to Step 25 | Go to Step 26

25

1. Inspect and repair the valve body for a hydraulic problem.
2. Inspect and repair for a clutch that is not fully releasing.

Is the inspection and repair complete?

--

Go to Step 51

--

26 | Do the TFP Switch and the gear ratio match the specified parameters? | Range A/B/C On On Off Ratio less than 0.95 but greater than 0.71 | Go to Step 27 | Go to Step 28

27

Inspect and repair the following items.

• | The fourth band is slipping or dragging

• | The third clutch is slipping

• | The fourth clutch is slipping

• | The forward sprag clutch has failed

Is the inspection and repair complete?

--

Go to Step 51

--

28 | Do the TFP Switch and the gear ratio match the specified parameters? | Range A/B/C On On Off Ratio greater than 1.05 | Go to Step 29 | Go to Step 30

29

Inspect and repair the following items.

• | The third clutch is slipping or dragging

• | The forward clutch is slipping

• | The forward sprag clutch has failed

Is the inspection and repair complete?

--

Go to Step 51

--

30 | Do the TFP Switch and the gear ratio match the specified parameters? | Range A/B/C On On Off Ratio greater than 1.71 | Go to Step 31 | Go to Step 32

31

Inspect and repair the following items.

• | The second clutch is slipping or dragging

• | The forward clutch is slipping

• | The forward sprag clutch has failed

Is the inspection and repair complete?

--

Go to Step 51

--

32 | Do the TFP Switch and the gear ratio match the specified parameters? | Range A/B/C On On Off Ratio less than 1.54 | Go to Step 33 | Go to Step 34

33

Inspect and repair the following items.

• | The third clutch is slipping or dragging

• | The forward clutch is slipping

• | The forward sprag clutch has failed

Is the inspection and repair complete?

--

Go to Step 51

--

34 | Do the TFP Switch and the gear ratio match the specified parameters? | Range A/B/C On On Off Ratio less than 2.87 | Go to Step 35 | Go to Step 36

35

Inspect and repair the following items.

• | The second clutch is slipping or dragging

• | The second sprag clutch has failed

• | The forward clutch is slipping

• | The forward sprag clutch has failed

Is the inspection and repair complete?

--

Go to Step 51

--

36 | Drive the vehicle in the 2nd gear range (ensure that 2nd gear is achieved). Do the TFP Switch and the gear ratio match the specified parameters? | Range A/B/C On On On Ratio less than 1.54 | Go to Step 37 | Go to Step 38

37

1. Inspect and repair the valve body for a hydraulic problem.
2. Inspect and repair for a clutch that is not fully releasing.

Is the inspection and repair complete?

--

Go to Step 51

--

38 | Do the TFP Switch and the gear ratio match the specified parameters? | Range A/B/C On On On Ratio greater than 1.05 | Go to Step 39 | Go to Step 40

39

Inspect and repair the following items.

• | The third clutch is slipping or dragging

• | The forward clutch is slipping

• | The forward sprag clutch has failed

Is the inspection and repair complete?

--

Go to Step 51

--

40 | Do the TFP Switch and the gear ratio match the specified parameters? | Range A/B/C On On On Ratio greater than 1.71 | Go to Step 41 | Go to Step 42

41

Inspect and repair the following items:

• | Second clutch slipping or dragging

• | Second sprag clutch failed

• | Forward clutch slipping

• | Forward sprag clutch failed

Is the inspection and repair complete?

--

Go to Step 51

--

42 | Do the TFP Val. Position Sw. and gear ratio match the specified parameters? | Range A/B/C On On On Ratio less than 1.54 | Go to Step 43 | Go to Step 44

43

Inspect and repair the following items:

• | The third clutch is slipping or dragging

• | The forward clutch is slipping

• | The forward sprag clutch has failed

Is the inspection and repair complete?

--

Go to Step 51

--

44 | Do the TFP Switch and the gear ratio match the specified parameters? | Range A/B/C On On On Ratio less than 2.87 | Go to Step 45 | Go to Step 46

45

Inspect and repair the following items:

• | The second clutch is slipping or dragging

• | The second sprag clutch has failed

• | The forward clutch is slipping

• | The forward sprag clutch has failed

Is the inspection and repair complete?

--

Go to Step 51

--

46 | Drive the vehicle in the 1st gear range (ensure that the vehicle stays in 1st gear). Do the TFP Switch and the gear ratio match the specified parameters? | Range A/B/C Off On On Ratio less than 2.87 | Go to Step 47 | Go to Step 48

47

1. Inspect and repair the valve body for a hydraulic problem.
2. Inspect and repair for a clutch that is not fully releasing.

Is the inspection and repair complete?

--

Go to Step 51

--

48 | Do the TFP Switch and the gear ratio match the specified parameters? | Range A/B/C Off On On Ratio greater than 3.11 | Go to Step 49 | Go to Step 50

49

Inspect and repair the following items.

• | The forward clutch is slipping

• | The forward sprag clutch has failed

• | The LO roller clutch has failed

Is the inspection and repair complete?

--

Go to Step 51

--

50 | Replace the PCM. Refer to PCM Replacement/Programming Section 6. Is the repair complete? | -- | Go to Step 51 | --

51

In order to verify your repair, perform the following procedure:

1. Select DTC.
2. Select Clear Info.
3. Operate the vehicle under the following conditions:

• | Road test the vehicle in all forward gears, and reverse.

• | With the gear select lever in D4, accelerate the vehicle with a throttle angle greater than 16°.

• | The engine torque must be greater than 135 N·m (100 lb ft).

4. Select Specific DTC. Enter DTC P0730.

Has the test run and passed?

--

System OK

Begin the diagnosis again. Go to Step 1