What Does P0654 Mean?
The engine RPM output signal circuit has a malfunction. The ECM has detected that the tachometer output signal it sends to the instrument cluster (or other modules) is not functioning properly. The driver may notice the tachometer reading zero, fluctuating erratically, or not responding to engine speed changes. This is the RPM signal output, not the crankshaft position sensor input.
Common Causes
30%
Open or damaged wiring in the RPM output signal circuit between ECM and instrument cluster
25%
Faulty instrument cluster (tachometer driver circuit failure)
20%
ECM internal RPM signal output driver failure
15%
Short to ground in the RPM signal wire
10%
Corroded connector at ECM or cluster causing intermittent signal loss
Diagnostic Steps
1
Observe the tachometer with the engine running. Note whether it reads zero, fluctuates, or tracks engine RPM normally. If the tachometer works fine, the code may be intermittent — check freeze frame data.
2
At the instrument cluster connector, back-probe the RPM signal input wire. With the engine running, use an oscilloscope or frequency counter to verify a pulsed square wave signal is present. The frequency should increase with engine RPM.
3
If no signal is present at the cluster, check the same wire at the ECM output connector. If the signal is present at the ECM but not at the cluster, there is an open in the wiring.
4
Perform a continuity and resistance check on the RPM signal wire from ECM to cluster. Check for shorts to ground (should read open/infinite resistance to chassis ground).
5
If the ECM is not producing the RPM output signal, use a bidirectional scan tool to command the tachometer. If the ECM cannot generate the signal, the internal output driver has failed.
Estimated Repair Cost
$50 - $500
Parts + labor, varies by vehicle and location
The engine RPM output signal circuit has a malfunction. The ECM has detected that the tachometer output signal it sends to the instrument cluster (or other modules) is not functioning properly. The driver may notice the tachometer reading zero, fluctuating erratically, or not responding to engine sp...
The most common cause of P0654 (Malfunction Indicator Lamp (MIL) Control Circuit Malfunction) is: Open or damaged wiring in the RPM output signal circuit between ECM and instrument cluster
Typical repair costs for P0654 range from $50 to $500, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Safe to drive. The engine runs independently of the tachometer output. However, without an accurate tachometer, you may not notice abnormal RPM conditions during driving. Other modules that rely on the RPM signal (like transmission control) typically get their own signal directly.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P0654 to identify the root cause.
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Quick Info
Category
Powertrain
System
Instrument Cluster / Engine RPM Signal
Difficulty
Type
Generic (SAE)
Recommended Tools
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