Guide To P0979 OBD Error Code Solutions

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What does P0979 error refer to? If the shift solenoid ‘C’ fails to shift in the correct way, then the P0979 error code will be stored. The hydraulic pressure of a vehicle has to be controlled where this function is performed by the TCM by using the shift solenoids. This is mainly needed to supply clutch packs in the transmission so that the vehicle will move forward efficiently when several gear ratios are applied. If the pressure control solenoid fails to work properly, then the P0979 error is set.

The shift solenoids are turned ON/OFF when the ECM commands the gear shifts to do so. Illumination of the engine light will take place if there is an opening or short-circuit in the shift solenoid circuit. This, in turn, is detected by the ECM and the error code is stored. Further, the failsafe function is initiated and other shift solenoid valves are also turned to decent condition ON/OFF.

What causes this problem with the Shift Solenoid "C" Control Circuit Low?

• Shift solenoid ‘C’ malfunctions.
• Shift solenoid ‘C has openings or the circuit is shorted.
• The electrical connection of shift solenoid ‘C’ is weak.

1. Engine Control Module - Fixing your faulty ECM helps you to get rid of the P0979 error code.
2. Transmission Fluid - Refill the fluid up to the correct level or change the transmission fluid if it is dirty.
3. Transmission Control Module - TCM will function effectively if it is damage free. You can find the replacement part from Parts Avatar.
4. Connector - Fixing your broken or faulty connectors is the best idea to avoid the P0979 error code getting stored.
5. Transmission Shift solenoid - Is this component broken? Is it malfunctioning? Grab the right replacement at best prices from Parts Avatar.

It is essential to know the symptoms of an issue as only then you would be able to solve the problem. So that’s why we have listed out some major symptoms of OBD Code P0979 here:

Common Symptoms 

You will face drivability issues as the TCM won’t be able to control SSC and few of the gears will become inaccessible in ‘D’ mode. Drivability issues will arise based on how the manufacturer uses the SSC. You will face weak acceleration and few gears will be locked out if the SSC is used for one of the brakes or the vehicle will face high revving before it shifts by shifting it to 5^th gear from 1^st gear. To regulate pressure or for torque converter lockup, SSC is basically used, where you will see fewer issues like rough shifts, relaxed engagement or reduced fuel economy from the ECM which has an open loop or the free torque converter.

After understanding the symptoms and few common causes behind the OBD error code, we are here to help you out in understanding the ways and means to correct the issue. To solve any issue you need to follow certain steps, and to solve OBD error code P0979, you will need to undergo the following replacements:

• Replacing the transmission fluid.
• As a rare case, you have to change the TCM/ECM or the connectors.

There is no need to be anxious as Parts Avatar - Car Parts Online is here to help you out! We have high-grade ECM, transmission fluid, TCM, connector, transmission shift solenoid and a lot more for our precious customers.

Here are some steps which you should follow in order to diagnose this fault code:

• This error is related to the electrical problem and so you must use a DVOM and electrical wire diagram (EWD) to perform a circuit check between the TCM and transmission. The wiring diagram which is specific to your vehicle will be available online or at an auto parts store or local dealership.
• Inspecting harness – Begin from ECM to TCM and then to the transmission to check wire harness. Check if you can see any defectives like rodent infestation or badly - routed harness followed by other repair works. A scratched wire harness can give rise to open or short-circuit related issues.
• See if all connectors are correctly linked. Separate these connectors and double check that there are no damaged pins, erosions or entry of water. You must note that an in-between condition may prevail at the firewall or at the linking of engine harness or transmission sub harness. Checkpoints can be easily found with the help of a wiring diagram.
• Circuit check - Turn off the key. See which circuit corresponds to SSC with the help of DVOM and EWD. Do a resistance test from TCM to SSC by either disconnecting the ECM or TCM connector.
• Check the resistance between the terminals or the body ground depending on your vehicle’s make and model. Double check with your EWD. Resistance must lie between 10 Ω and 20 Ω.
• On measuring the acceptable resistance, you will find the ECM to be faulty or an erratic harness issue. Don’t judge unless everything is checked. Clearly see the resistance measurement and the erratic harness issue can be inspected by shaking the wires and connectors.
• You will find less resistance and a short-circuit where you must re-check the harness for resistance in case of P0979. Calculate the resistance at the TCM connector by removing the transmission connector. Repair the harness for short-circuit if it’s not between 10 Ω and 20 Ω. Finally, repair the shift solenoid if the harness is not good.
• Solenoid Check - At times SSC may not be located inside the transmission based on your vehicle make & model. If it’s outside, check the resistance at the connector. If you find it inside, double check the measurement of resistance at the transmission connector. If there is an open- circuit or if there is no connection to ground, one or more sub-harness will be linked to the solenoid and you have to access the transmission pan by dropping it.
• Now the internal sub-harness of the transmission and the solenoid is left behind. Doing a circuit check will let you know if there is an open circuit or breaks in the sub-harness. Test the solenoid for functionality by using a jumper. Repair as needed.

Common Mistakes When Diagnosing The P0979 Code

• Defective transmission control module.
• Low-level fluid in the transmission.
• Broken transmission shift solenoid.
• An issue with the electrical wires.