In order to know whether or not the transmission has applied the next ratio, the ECU relies on a number of sensor inputs, like those from the input speed sensor and output speed sensor. Data that does not add up to predetermined parameters will trigger this code. However, a P2704 DTC can also be triggered if there is enough hydraulic pressure to engage a particular clutch.
How Serious is the Code?
Having a P2704 OBDII diagnostic trouble code means that the computer has detected a situation to where the transmission is not changing gears in the way that it should. This can obviously lead to slipping and other drivability concerns. However, can also be a symptom of rather severe transmission problems (see: expensive) that need to be addressed sooner than later.
Symptoms of a P2704 include:
- Harsh shifts
- Slipping between gears
- Failure to change gears
- Limp mode
- Low transmission fluid
- Dirty transmission fluid/clogged filter
- Damage to the wiring or connectors
- Bad transmission pump
- Overheating transmission
- Faulty TCM
- Faulty input speed sensor / output speed sensor
How to Diagnose the Code?
The transmission fluid is one of the first things that should be checked when trying to diagnose a P2704 OBDII diagnostic trouble code. Dirty transmission fluid can prevent the transmission from changing gears properly, and transmission fluid leaks can reduce hydraulic pressure to the point that gear changes cannot happen when they need to.
If the transmission problems are detected up to this point, then the wiring and connectors on the transmission wiring harness need to be inspected for signs of damage or corrosion. Should no issues be found, the input speed sensor, output speed sensor and transmission pump should be tested.
What Repairs Will Fix P2704?
- Change the transmission fluid/filter
- Repair transmission fluid leaks
- Repair damage wiring/connectors
- Install new transmission pump
- Install new TCM
- Install new output speed sensor/input speed sensor
- Install remanufactured transmission
P2700 – Transmission Friction Element A Apply Time Range/Performance
P2701 – Transmission Friction Element B Apply Time Range/Performance
P2702 – Transmission Friction Element C Apply Time Range/Performance
P2703 – Transmission Friction Element D Apply Time Range/Performance
P2705 – Transmission Friction Element F Apply Time Range/Performance