P06AC PCM / ECM / TCM Internal temperature sensor B: range / performance

P06AC PCM / ECM / TCM Internal temperature sensor B: range / performance

OBD-II DTC Datasheet

PCM / ECM / TCM Internal Temperature Sensor B - Range / Performance

What does this mean?

This is a Generic Powertrain Diagnostic Trouble Code (DTC) applicable to many OBD-II vehicles (1996 and newer). This may include but is not limited to Mazda, Honda, Dodge, Ford, BMW, VW, etc. Despite the general nature, the exact repair steps may vary depending on the model year, make, model and transmission configuration.

OBD-II trouble codes P06AB, P06AC, P06AD and P06AE are associated with the internal temperature sensor “B” circuit of various modules. This circuit includes a power control module (PCM), an engine control module (ECM), and / or a transmission control module (TCM). Consult your specific vehicle repair manual to determine which circuit “B” is in your particular case.

The internal temperature sensor “B” circuit of the PCM / ECM / TCM is designed to monitor the temperature of various sensors located in the control modules. Malfunctions are detected in the process of failures of the self-test of the control module. On some vehicles, three modules are combined into one combined unit, commonly referred to as the PCM.

When the PCM, ECM, or TCM detects electrical signals outside the normal range on the "B" internal temperature sensor circuit, P06AC will set and the engine warning lamp or transmission warning lamp will illuminate.

Example of a TCM transmission control module:

What is the severity of this DTC?

The severity of this code can vary greatly from just a lit engine warning light or a transmission warning light on a vehicle that starts and moves to a vehicle that stalls or won't start at all. The code can be serious depending on the specific nature of the problem.

What are some of the symptoms of the code?

Symptoms of a P06AC trouble code may include:

• The engine will not start
• Engine may stall
• Incorrect switching
• Transmission warning lamp is on
• Check engine light is on

What are some of the common causes for the code?

Reasons for this P06AC code may include:

• Corroded or damaged connector
• Loose or defective control module ground strap
• Faulty or damaged wiring
• Defective PCM, ECM or TCM

What are some P06AC troubleshooting steps?

The first step in troubleshooting any problem is to review the vehicle-specific Technical Service Bulletins (TSBs) by year, model, and powerplant. In some cases, this can save you a lot of time in the long run by pointing you in the right direction.

The second step is to locate all the control modules in that circuit and perform a thorough visual inspection to check the associated wiring for obvious defects such as scratches, frays, exposed wires, or burn marks. This process should also include ground straps and ground wires. Next, you should check the connectors for security, corrosion and damage to the contacts. This process should include the PCM, ECM and TCM depending on the specific vehicle and control module configuration. The specific technical data for the vehicle will help you with the location of the components and the configuration of the control module.

Advanced steps

The additional steps become very vehicle specific and require appropriate advanced equipment to be performed accurately. These procedures require a digital multimeter and vehicle-specific technical reference documents. Specific technical data will include troubleshooting tables and appropriate sequence of steps to help you make an accurate diagnosis.

Voltage test

Specific troubleshooting guidelines should be consulted to determine the voltage ranges required for the various control modules. These references will include pin numbers and voltage requirements that relate to the internal PCM / ECM / TCM temperature sensor / circuit. Most, but not all control modules require a reference voltage of approximately 9 volts. Voltage requirements vary by year and vehicle model.

If this process detects that a power source or ground is missing, a continuity test may be required to verify the integrity of wiring, connectors, and other components. Continuity tests should always be done with power disconnected from the circuit and normal wiring and connection readings should be 0 ohms. Resistance or no continuity indicates faulty wiring that is open or shorted and requires repair or replacement. Continuity testing from the various control modules to the frame will confirm the level of functionality of the ground straps and ground wires. Resistance indicates a loose connection or possible corrosion.

What are the standard ways to fix this code?

• Cleaning connectors from corrosion
• Repair or replace faulty wiring
• Repair or replacement of faulty grounding tapes
• Flashing or replacing PCM, ECM or TCM

Misdiagnosis can lead to PCM, ECM or TCM replacement often being done in error when faulty wiring and loose connections trigger this code. In addition, on vehicles equipped with two or more control modules, the wrong module may be replaced by mistake.

Hopefully, the information in this article has helped point you in the right direction to troubleshoot your PCM / ECM / TCM / Circuit Internal Temperature Sensor DTC problem. This article is for informational purposes only and specific technical data and service bulletins for your vehicle should always take priority.

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