P0899 Possible Causes
Faulty Transmission Control Module (TCM)
Transmission Control Module (TCM) harness is open or shorted
Poor electrical connection in Transmission Control Module (TCM) circuit
What Does It Mean?
Check the “Possible Causes” listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector pins.
P0899 Possible Symptoms
Illuminated engine light (or service engine soon warning light)
P0899 Meaning
The Transmission Control Module (TCM) requests the Engine Control Module (ECM) to activate the Malfunction Indicator Light (MIL). The ECM sets the OBDII code when there is a communication issue with the TCM via the MIL request circuit.
OBDII Code P0899 – Transmission Control System MIL Request Circuit High