Test Q: DTC B2521 - Driver Tach Circuit Failure; DTC B251A - Passenger Tach Circuit Failure; DTC B272E - Driver Ignition Run/Bl

PINPOINT TEST Q: DTC B2521 - DRIVER TACH CIRCUIT FAILURE; DTC B251A - PASSENGER TACH CIRCUIT FAILURE; DTC B272E - DRIVER IGNITION RUN/BLOWER CIRCUIT SHORT TO GROUND (DRIVER OR PASSENGER)

Q1:

Q1-Q3:

Q3-Q4:

Q4 Continued:

Q5:

Q5-Q6:

Q6-Q7:

Q7-Q8:

Q8-Q9:

Q9-Q10:

Q10 Continued:

Normal Operation
The dual climate controlled seat module (dual CCSM) provides voltage on circuit 1552 (RD) and ground on circuit 1553 (BK) to operate the climate controlled seat blower fan. The dual CCSM also supplies voltage on circuit 1565 (VT) that is used by the climate controlled seat blower fan to provide a feedback voltage to the dual CCSM indicating climate controlled seat blower fan speed.

Possible Causes
An ignition switch or blower electronics circuit short to ground or a tach circuit failure can be caused by:
- wiring, terminals or connectors.
- dual CCSM.
- climate controlled seat blower fan.