Tachometer Circuit Malfunction
What does B1402 mean?
The B1402 code means the vehicle's onboard diagnostic system has detected: Tachometer Circuit Malfunction. This is a low severity code.
Common Symptoms
- Tachometer not reading RPM
- Tachometer needle bouncing
- Tachometer stuck at a fixed position
- Tachometer reads higher or lower than actual RPM
- Intermittent tachometer operation
Probable Causes (Ranked by Likelihood)
- Faulty tachometer stepper motor in cluster Very High
- Lost RPM signal from PCM to cluster High
- Instrument cluster internal circuit fault Moderate
- CAN bus communication error Moderate
- Damaged wiring between PCM and cluster Low
Step-by-Step Diagnostic Procedure
-
Check RPM reading on scan tool and compare to tachometer
-
Verify CAN bus communication between PCM and cluster
-
Perform instrument cluster self-test
-
Check for related PCM codes
-
Inspect cluster connector for loose or corroded pins
Frequently Asked Questions
Is it safe to drive without a working tachometer?
Yes. The tachometer is an informational gauge. You can drive safely without it, though you will lose the ability to monitor engine RPM for optimal shift points.
Why does the tachometer read incorrectly?
An incorrect reading can be caused by a failing stepper motor in the cluster, an incorrect RPM signal from the PCM, or a CAN bus communication glitch.
Can aftermarket tachometers be added?
Yes. If the built-in tachometer cannot be repaired cost-effectively, aftermarket tachometers can be mounted on the dashboard or A-pillar as an alternative.