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P0890 is a diagnostic trouble code (DTC) for "Traction Control Module (TCM) Power Relay Sense Circuit Low". This can happen for multiple reasons and a mechanic needs to diagnose the specific cause for this code to be triggered in your situation. Our certified mobile mechanics can come to your home or office to perform the Check Engine Light diagnostic. Once we are able to diagnose the problem, you will be provided with an upfront quote for the recommended fix and receive $20.00 off as a credit towards the repair. All our repairs are backed by our 12-month / 12,000-mile warranty.
Applying only to vehicles with a traction control system, a P0890 trouble code indicates a fault in the traction control module communication circuit. The traction control module communication circuit relays information to the Powertrain Control Module (PCM) that helps the vehicle computer decide on how much fuel and RPMs the vehicle engine needs depending on current driving conditions and factors. The traction control module communication circuit also helps with engine timing and other things while the vehicle is in operation. Some similar trouble codes include P0880, P0881, P0882, P0883, P0884, P0885, P0886, P0887, P0888, P0889, P0891, and P0892 codes.
When the PCM or other control modules do not receive the necessary data from the traction control module communication circuit, a P0890 trouble code is stored and the Check Engine light may illuminate, in addition to the traction control malfunction light illuminating. The PCM might also place the vehicle transmission into Limp-in mode.
A defective traction control ON/OFF switch is the most common cause of a P0890 trouble code, with liquid spilled into the switch being the most likely culprit behind the failure. Some other causes include shorted, corroded, and damaged wiring or connectors, as well as corrosion in the sensor connector.
In addition to a stored code and illuminated Check Engine and Traction Control Malfunction lights, some other symptoms of a P0890 trouble code include a lack of traction while driving in slippery conditions and failure of the traction control system. Other symptoms include harsh shifting or failure to shift by the transmission, as well as a reduction in the fuel efficiency of the vehicle.
To properly diagnose a P0890 trouble code, a mechanic needs an advanced scanner, digital volt/ohmmeter, a specialized scanner for diagnosing the pins of the Controller Area Network (CAN) Bus harness, auxiliary ground cable, and a CAN Bus system wiring diagram. The mechanic must also perform the following steps when diagnosing:
When diagnosing a P0890 trouble code, mechanics often make the mistake of citing the traction control module as the problem instead a faulty switch, wiring, or connector, which is actually at fault. This results in the problem remaining unfixed and the trouble code returning.
A P0890 trouble code needs to be dealt with as soon as possible. The resulting symptoms make the vehicle difficult to drive at best. Some of the problems associated with a P0890 trouble code include loss of traction, failure of the transmission to shift properly, and worsening fuel mileage.
Repairing a P0890 trouble code requires a mechanic to do the following:
If replacing wiring in the CAN Bus harness, the mechanic might be better served replacing the whole harness as opposed to individual wires.
Replace any faulty control modules, including the traction control module if faulty.
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