The 1-2 shift solenoid (SS) valve controls the fluid flow action
on the 1-2 and the 3-4 shift valves. The 1-2 SS valve
is a normally-open exhaust valve that is used with
the 2-3 SS in order to allow four different shifting
combinations.
When the powertrain control module (PCM) detects a 2-2-3-3
gear ratio, then DTC P0751 sets. DTC P0751 is
a type C DTC. For California emissions vehicles
and vehicles under 8,600 GVW, DTC P0751 is a
type B DTC.
The numbers below refer to the step numbers on the diagnostic table.
Step
| Action
| Value(s)
| Yes
| No
|
1
| Did you perform the Diagnostic System Check - Engine Controls?
| --
| Go to
Step 2
| Go to
Diagnostic System Check - Engine Controls
in Engine Controls - 6.0L
|
2
|
- Install a scan tool.
- Turn ON the ignition, with the engine OFF.
Important: Before clearing the DTCs, use the scan tool in order to record the
Freeze Frame and Failure Records. Using the Clear Info function erases
the Freeze Frame and Failure Records from the PCM.
- Record the Freeze Frame and Failure Records.
- Clear the DTCs.
- Select TFP switch A/B/C on the scan tool.
- With the engine operating, apply the brake pedal, and select each
transmission range: D1, D2, D3, D4, N, R, and P.
Refer to
Transmission Fluid Pressure Manual Valve Position Switch Logic
.
Does each selected transmission range match the scan tool TFP switch display?
| --
| Go to
Step 3
| Go to
DTC P1810
|
3
|
- Raise and support the drive axle assembly.
- Start the engine.
- With the transmission in D4 range, use the scan tool in order
to command FIRST, SECOND, THIRD, and FOURTH gears while accelerating the
vehicle.
The vehicle may need to be road
tested.
Was a 2-2-3-3 shift pattern only detected?
| --
| Go to
Step 4
| Go to Diagnostic Aids
|
4
|
- Inspect the transmission for the following conditions:
• | 1-2 shift solenoid mechanically stuck OFF |
• | 1-2 shift valve stuck in the released position |
• | Damaged 1-2 shift solenoid seals |
- Repair the condition as necessary.
Did you complete the repair?
| --
| Go to
Step 5
| Go to Diagnostic Aids
|
5
| Perform
the following procedure in order to verify the repair:
- Select DTC.
- Select Clear Info.
- Operate the vehicle under the following conditions, if traffic
and road conditions permit:
• | Accelerate the vehicle with the throttle angle greater than 7 percent
up to 89 km/h (55 mph). |
• | The PCM must see the proper ratio for each commanded gear for
greater than one second in D1, D2, D3, and D4. Wait for the TCC Lock-up
in 4th gear. |
- Select Specific DTC.
- Enter DTC P0751.
Has the test run and passed?
| --
| Go to
Step
6
| Go to
Step
2
|
6
| 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?
| --
| Go to
Diagnostic Trouble Code (DTC) List
in Engine Controls - 6.0L
| System OK
|