P068B – Relay ‘Circuit 87’ has shut off too late. There is an internal fault.

DTC P068B is an ISO/SAE controlled, powertrain-related code with the official meaning: Relay “Circuit 87” has shut off too late. There is an internal fault. In other words, the powertrain control module (PCM) detected that the relay’s switched output (circuit/terminal 87) did not turn off within the time window the PCM expects during the key-off shutdown sequence, and the PCM also flagged an internal fault condition associated with that event. Because circuit 87 is typically a primary power feed to the PCM and other engine-management loads, late shutoff can interfere with proper module sleep, cause unstable shutdown behavior, or contribute to battery drain. Accurate diagnosis focuses on confirming actual circuit 87 shutoff timing and integrity.

P068B Quick Answer

P068B means the PCM detected that relay “Circuit 87” shut off too late and the event is associated with an internal fault flag. Verify the circuit 87 output drops to 0 V within the expected key-off window, then check the relay, relay socket, wiring, and any backfeed that could keep circuit 87 powered before considering an internal module issue.

What Does P068B Mean?

The official meaning of P068B is: Relay “Circuit 87” has shut off too late. There is an internal fault. This description should be treated literally: the PCM monitored the shutdown of the relay output identified as circuit 87 and determined the power-down occurred later than allowed by its calibration, while also identifying an internal fault condition tied to that shutdown evaluation.

Circuit 87 is the relay’s switched output contact (the feed that becomes powered when the relay is energized). The PCM may monitor this output directly through a sense circuit, indirectly through its own power state, or through related status logic. When the measured or inferred voltage on circuit 87 remains present longer than expected after key-off, the PCM stores P068B to indicate the “too late” shutoff along with the internal-fault qualifier contained in the standardized definition.

Theory of Operation

During normal operation, the relay associated with circuit 87 closes to supply battery voltage to key powertrain loads. When the ignition is turned off, the PCM transitions through a shutdown routine and expects the relay output (circuit 87) to drop out within a defined time limit. Some vehicles may intentionally keep certain circuits awake briefly, but the PCM still uses an expected timing window for when circuit 87 should no longer be energized.

P068B sets when the PCM detects that circuit 87 remains powered beyond that allowable window. This can happen because the relay contacts do not open promptly, the relay coil remains energized longer than intended, or voltage is being fed onto circuit 87 from another path. The “internal fault” wording is part of the official definition and indicates the PCM recognized an internal fault condition associated with the shutoff-too-late detection; it does not eliminate the need to verify external circuitry and power distribution behavior first.

Symptoms

• Battery drain after key-off due to delayed power-down behavior.
• Electrical loads behaving unexpectedly after shutdown (for example, relay activity or components remaining powered).
• Intermittent no-start or hard-start following a short or overnight sit.
• Malfunction indicator lamp (MIL) illuminated or a stored/pending P068B.
• Intermittent module reset behavior around key cycles (such as unstable power-down/power-up symptoms).

Common Causes

• Relay contacts that stick or release slowly, keeping circuit 87 powered longer than intended.
• Relay socket or terminal issues (poor tension, heat damage, corrosion) affecting proper relay operation or creating unintended current paths.
• Relay control circuit staying energized too long (coil feed or control/ground side not dropping out as expected).
• Backfeed onto circuit 87 from another circuit or load, holding voltage on the output even after the relay is commanded off.
• Power or ground integrity problems affecting the PCM’s shutdown behavior or its ability to evaluate circuit 87 timing correctly.
• Internal fault within the module related to the shutoff-too-late detection (to be considered only after external checks are proven good).

Diagnosis Steps

Tools needed: scan tool capable of reading freeze-frame and live data, a digital multimeter (DMM), wiring diagrams for the exact vehicle, and basic backprobing/terminal-inspection tools. If available, a fused test light and an ammeter or current clamp can help verify key-off current draw and confirm whether circuit 87 is staying powered.

1. Verify the code and capture data. Confirm P068B is present (stored or pending) and record freeze-frame information. Note battery voltage and any related power supply or voltage codes that could affect shutdown behavior.
2. Check for related symptoms at key-off. With the vehicle safely parked, perform a controlled key-off event and observe whether any powertrain-related relays or underhood electrical activity continues longer than expected.
3. Identify the exact relay and circuit 87 path. Using the wiring diagram, confirm which relay output is designated as circuit/terminal 87 for this application and which fuses/loads are supplied by that output.
4. Perform a visual inspection of the relay and power distribution area. Inspect the relay, relay cavity, surrounding fuses, and harness routing for heat discoloration, melted plastic, corrosion, water intrusion, or loose terminals.
5. Measure circuit 87 voltage drop-out timing. Backprobe the circuit 87 output at the relay socket (or at an accessible downstream point) and monitor voltage during key-on and key-off transitions. Confirm whether circuit 87 drops to 0 V promptly after key-off or remains powered longer than expected.
6. Differentiate “relay staying on” vs. “backfeed.” Remove the relay and check for voltage present on the harness side of the circuit 87 terminal with the ignition off. If voltage remains with the relay removed, isolate backfeed by disconnecting loads or pulling related fuses one at a time (following the wiring diagram) until the voltage disappears.
7. Check relay control (coil) behavior. Measure voltage and/or control state at the relay coil terminals (typically 85/86) during key-off. Determine whether the coil command drops out when expected. If the coil remains energized too long, trace upstream control inputs and grounds according to the diagram.
8. Load-test power and ground integrity. Perform voltage-drop tests on the main battery feeds and PCM grounds relevant to the relay/PCM power supply while the circuit is under load. Excessive voltage drop can distort shutdown behavior and lead to timing-related faults.
9. Inspect terminal fitment and contact quality. Check for spread terminals, poor pin tension, pushed-out terminals, or signs of arcing at the relay socket and any in-line connectors on the circuit 87 path. Repair terminal problems before replacing major components.
10. Confirm the fix and recheck. After repairs, clear codes, perform multiple key cycles, and re-measure circuit 87 shutoff behavior. Re-scan for pending/stored faults and confirm P068B does not return under the same operating conditions.

Professional tip: When validating “shut off too late,” rely on measured behavior, not assumptions. A circuit can show near-battery voltage with a DMM even through an unintended backfeed path; removing the relay and testing the harness side of circuit 87 is a direct way to separate a sticking relay from voltage being held up by another circuit.

Possible Fixes

• Repair or replace damaged relay socket terminals (heat damage, corrosion, poor tension) affecting circuit 87 operation.
• Correct wiring faults on the relay control circuit that keep the coil energized too long.
• Eliminate backfeed sources by repairing miswired connections or isolating the branch/load that is feeding circuit 87 with the relay off.
• Restore battery cable and ground integrity where voltage-drop testing identifies excessive resistance.
• Replace the relay if testing confirms the contacts stick or the relay fails to release promptly.
• Address an internal module fault only after external circuit behavior and power distribution checks confirm proper operation and P068B persists.

Can I Still Drive With P068B?

Driving with P068B is a reliability risk because the code indicates circuit 87 shuts off too late and the event includes an internal fault flag. If circuit 87 stays powered after key-off, the vehicle may not shut down cleanly, which can contribute to battery drain or an intermittent no-start. If you experience starting problems, unexpected electrical behavior after shutdown, or a rapidly discharging battery, limit driving and diagnose the fault promptly to avoid being stranded.

How Serious Is This Code?

P068B can be serious because circuit 87 is a primary switched power feed and its delayed shutoff can affect proper PCM shutdown and power management. The impact ranges from minor inconvenience to repeated no-starts or electrical instability after key cycles, depending on whether the circuit remains energized and how long it stays on. Because the official meaning includes an internal fault condition, the code should be treated as a valid indicator that the shutdown event did not meet expected behavior and warrants structured testing of the power relay output, control path, and power/ground integrity.

Common Misdiagnoses

A frequent misdiagnosis is replacing the relay solely because the description references a relay, without first proving whether circuit 87 truly remains powered too long or whether voltage is present due to backfeed. Another error is skipping voltage-drop testing and relying only on continuity checks, which can miss high resistance at terminals and connections that affects shutdown evaluation. Finally, assuming the internal fault wording automatically means the PCM must be replaced can lead to unnecessary module replacement if circuit 87 behavior is being held up by wiring, terminal, or power distribution issues.

Most Likely Fix

The most likely repair path is to restore correct circuit 87 shutoff behavior by addressing the relay, relay socket, and any backfeed or control-circuit condition that keeps the output energized past the expected key-off window. After verifying circuit integrity and proper coil command drop-out, replace the relay only if testing confirms it releases late or sticks. If circuit 87 and its control behave correctly and P068B still repeats under the same conditions, further evaluation of the internal fault condition is warranted using vehicle-specific diagnostic information.

Repair Costs

Repair cost depends on whether the confirmed root cause is wiring, connector condition, a sensor, a module, or the labor needed to diagnose the fault correctly.

Last updated: April 3, 2026