P0748 - OBD Trouble Code

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The automatic transmission has a purpose, which is to match the engines optimum power and torque characteristics to the rate of speed desired by the driver when accelerating. This happens by auto-selection of different gear ratios or speeds to power the wheels accordingly. The hydraulic pressure in the transmission is controlled by the Pressure Control solenoid. This is needed so that various clutch packs can be applied in the transmission, which leads to provision of different gear ratios. This in turn propels the vehicle down the roadways properly.

The P0748 code is set by the Powertrain Control Module or PCM. This error is set when the PCM is experiencing an electrical malfunction related to the pressure control solenoid.

What causes this problem with the Pressure Control Solenoid A Electrical?

• Contamination or dirt in the transmission fluid
• Transmission fluid level is low
• Transmission fluid passage ways clogged
• Poor electronic pressure control solenoid
• Failure of mechanical internal transmission
• A malfunctioning TCM (transmission control module)
• A malfunctioning PCM (rare)

1. Pressure Control Solenoid - Depending on the extent of damage, you can fix it or opt for replacement.
2. Transmission Filter - You can order a replacement online 24x7 from Parts Avatar and resolve this P0748 error. We ship across Canada.
3. Transmission Pump - Repair and replace the pump as needed.
4. Transmission Valve - At Parts Avatar we have the best brands offering top quality auto parts, it’s simple to order, and you can track your shipment till it reaches you at your doorstep!
5. Pressure Control Solenoid Connector - Repair the problem or replace it as required.
6. Hydraulic Pipes - Try to repair if that’s not helping, you can always opt for replacement. At times replacements are the only option to get rid of the P0748 error in vehicles.
7. Powertrain Control Module - Replace your PCM with us, we offer free shipping on orders over CAD $99.

Our main motive is to achieve customer satisfaction and that’s why we will help you to diagnose P0748 code by mentioning some major symptoms below:

Common Symptoms

• Check Engine Light is lit
• Vehicle no longer shifts from gear to gear as normal
• Vehicle may not be driveable anymore
• Reduction in fuel economy

Have a look at some ways with which you can correct the P0748 code:

• Repairing pressure control circuitry (wiring and connectors)
• Replacement of the pressure control solenoid
• Replacement of the electronic pressure regulator
• Rebuilding or replacing the complete transmission, not excluding the torque converter
• Flushing and fully replacing the transmission fluid
• Replacement of TCM

Don’t get tensed if you are still facing any of these issues as we care for our customers and that’s why we offer a good range of Pressure Control Solenoid, Transmission Filter, Transmission Pump, Transmission Valve, Pressure Control Solenoid Connector, Hydraulic Pipes, Powertrain Control Module and a lot more. We are sure that now all your issues would be resolved.

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

• Start by inspecting the transmission fluid dipstick. The transmission fluid should be of optimum level required by the vehicle as per guidelines of the manufacturer. Also check the condition of the transmission fluid, there should be no burned smell or contaminants in it. Any such findings will support inadequacy of the fluid. Remove the transmission pan and check for clutch material or other debris present there.
• If the fluid is burned, its a sign that the transmission was operating when there was low level of fluid. And the transmission may have hence suffered catastrophic internal mechanical failure as well.
• Now proceed to spotting any shorted or burned wiring, connectors or circuitry. Repair or replace them as needed. If the system wiring, connectors and components all seem to be normal, then you can connect the scanner to your vehicle's diagnostic port and retrieve all the codes and freeze frame the data. For future reference it will be important to also make note of all these codes if the problem is intermittent. You can now safely clear all codes and go on a test-drive to see if the PCM enters readiness mode or if the code immediately resets. You will accordingly need to resolve the issues.
• If the code doesn’t reset, that would mean you have an intermittent condition, and these are quite a challenge, in some cases the condition may have to worsen to be able to diagnose the problem accurately.
• To make repairs you have to refer your manufacturers specifics and match them accordingly. There are some common causes of low pump pressure like clogged hydraulic passages, a defect in the pump itself, fault in the shift solenoids, or a faulty electronic pressure regulator. Replacement of pump will require transmission removal and also partial disassembly.
• Upon test drive if the code returned immediately but the transmission seemed to be operating as normal, you will have to check reference voltage and ground signals at the electronic pressure control solenoid. Repair and replace the system circuits/connections as needed. Remember to retest the system and ensure that the repairs and replacements have been successful. This is a very important step in this diagnosis.
• Refer the vehicle manufacturers information to locate the electronic pressure control solenoid, and test all related circuits and the solenoid as well. You are testing it for resistance as well as continuity. Again, compare the findings to the ones provided by your vehicle manufacturer.
• If all the system circuits are intact, then you can connect the scanner to the diagnostic connector and attempt to manually activate the electronic pressure control solenoid. If the solenoid fails to activate manually, then go ahead and replace it and retest the whole transmission control system.
• If all is fine with the solenoid as well the circuit readings, you can now safely suspect a defect with the high-pressure pump, torque converter, or PCM. PCM failure is super rare, and replacement can not only be expensive but also require reprogramming by a professional.

Common Mistakes When Diagnosing the P0748 Code

• Concluding that the code has to do with an engine misfire
• Assuming that the code is set due to problems with the high-pressure pump
• Overlooking wiring and circuitry as the problem makers