P0740 - OBD Trouble Code
OBD Code P0740 - Torque Converter Clutch Circuit Malfunction
OBD-II
Code P0740 is also known as a ‘Torque Converter Lockup Malfunction’. It is a
generic code and found commonly in OBD-II vehicles. It mainly points out issue
present within the transmission range sensor. You may find this code being set
along with various other transmission codes too.
Learn More About OBD Error Code P0740
In
this code, what is basically happening is that the Powertrain Control Module or
PCM module has detected some unusual activity within the torque convertor
clutch circuit of the vehicle. The Engine Control Module or ECM is capable of
varying the torque converter clutch circuit application as per the requirement
of the vehicle and its performance. In case the torque converter clutch
application is malfunctioning and its noted that multiple times, the PCM module
will trigger a ‘check engine’ light and set P0740 code.
What causes this problem with
the Torque Converter Clutch Malfunction?
- A
malfunctioning torque converter clutch solenoid
- Damages
present of the torque converter or clutch
- Wrong
transmission fluid level
- Skipping
over of transmission maintenance
- Any
constraints within the transmission
- Internal transmission damages present
- An
improper powertrain control module or transmission module
Replace/Repair These Parts To Fix OBD Code P0740
- Transmission
Fluid - You may need to refill or replace the dirty transmission
fuel. Don’t miss this part and go for the best quality transmission fuel for
your vehicle.
- Torque Converter
Clutch Solenoid - Simply repair or opt for replacement. At Parts Avatar we provide the best OEM car parts, and you will
definitely find ones that are compatible to your vehicle. Order Online today!
- Torque Converter Clutch Solenoid Valve harness - Repair the harness, or
replace it to get rid of P0740 error code.
- Transmission Valve Body - You may have to replace it, order online and avail free shipping on orders over CAD $99. This will help you resolve the P0740 error that’s flashing.
- Transmission
Control Module - Try and repair the damages observed. If needed you can replace it
with a new one by simply ordering online from Parts Avatar, we ship in just few
days!
Symptoms Of OBD Error Code P0740
The
symptoms exhibited by your vehicle will help you understand which of them are
related to the OBD error code P0740. We at Parts Avatar, have listed few common
symptoms you may be able to find and hence help you in the diagnosis of the
error code.
Common Symptoms
- The
transmission showing issues with shifting in or out of a particular gear
- The
transmission may shift but in a rough manner
- Vehicle
is unable to move due to the torque converter clutch not engaging or
disengaging
- The
engine may stall out
- The
transmission may overheat
How To Correct P0740 Torque Converter Clutch Circuit Malfunction
Here
are some ways with which you can correct the P0740 code:
- Replace
the torque converter clutch solenoid
- Replace
the torque converter or clutch
- Adding
or replacing transmission fluid and its filter
- Completely
replacing the powertrain control module/ PCM
- Repairing
the current transmission
- Replace the complete transmission with a new one
You
can find all your replacements needs at one place at Parts Avatar. Order
online, from the comfort of your home. We have a wide range of parts compatible
for a large variety of cars. We ship across Canada, and accept bulk orders too!
Easy Diagnosis Of Engine Error OBD Code P0740
Diagnostics
don’t have to be painful or confusing, hence we have laid down simple steps for
diagnosis for you here:
- Start
by checking the transmission fluid and see if it’s in proper condition and at
the optimum level required by your vehicle. If you notice any abnormality, then
this could’ve been the issue. Accordingly resolve it by adding more or changing
the transmission fluid.
- Now
check the transmission wiring harness for any damages or loose connections. For
this you can take help from a factory wiring diagram and locate the appropriate
power source and all the points of connections between the circuits. A fuse or
relay may be powering the transmission and have gotten triggered by the TCM.
- Now
disconnect the harness of the transmission at the connector, power source as
well as the TCM. Locate the appropriate positive and negative pins of the
torque converter clutch solenoid to check for continuity inside the
transmission internal wiring harness.
- Now,
use the DVOM (digital volt ohm meter) set it to ohms scale and check for the
resistance in the circuit, by connecting the positive and negative leads to the
appropriate pins. Observe the resistance reading. If it is too high and over
limit (OL), then suspect a fault with the internal harness or the TCC solenoid.
It will be necessary to remove the transmission oil pan for further diagnosis
of the TCC solenoid
- Use
the DVOM again, set it to ohms, and test the wiring between the TCM and wiring
harness connector at the transmission case. Observe for any short to ground,
you can do this by moving the negative lead on the DVOM to any good ground
known. Resistance should be high or even OL (over limit).
- Now
check the resistance at the TCC solenoid as well as the internal transmission
wiring at the transmission case. Do this after removing the plug of the
transmission harness.
- Along
with the TCC solenoid and internal harness, some vehicles use a transmission
wire harness too as a single unit. Set your DVOM to ohms scale and connect the
positive and negative leads on the pins for the TCC power and control circuit.
- Now
check for voltage on the power side circuit of the TCC solenoid. You can also
do this at the wire harness connector at the TCM. Use a DVOM, but this time set
it to volts scale. The positive lead should be at the wire that is to be tested
and the negative lead to any known ground which is good. Keep the vehicle's
engine off and key on, there should be presence of battery voltage.
- It is mandatory to monitor the TCM with an advanced scan tool, since the torque converter clutch only gets activated during particular driving situations. This is to determine if the TCm is commanding the TCC solenoid and the feedback that is being read at the TCM. The vehicles TCC solenoid is typically in control by a duty cycle, which engages for a more comfortable torque converter clutch engagement.
Common Mistakes When
Diagnosing the P0740 Code
- Ignoring or overlooking common causes like dirty transmission fluid or misadjusted position sensor and proceeding with replacement of components that were working just fine.
- Not
following the diagnostic steps in order, or not completing them as needed for
accurate diagnosis for OBD error P0740