Acura RL. Instruction — page 100

PCM memory.

Conditions for clearing the MIL

The MIL will be cleared if the malfunction does not recur during three consecutive trips in which the
diagnostic runs.

The MIL, the DTC, and the freeze frame data can be cleared by using the scan tool Clear command or by
disconnecting the battery.

DTC P2648 (21): ADVANCED DIAGNOSTICS (L4 ENGINE A/T)

DTC P2648: ROCKER ARM OIL CONTROL SOLENOID (VTEC SOLENOID VALVE) CIRCUIT
LOW VOLTAGE

Fig. 311: Rocker Arm Oil Control Solenoid (VTEC Solenoid Valve) Circuit Diagram (Low Voltage)

General Description

The VTEC system switches the valve timing by opening and closing the oil passage to the high/low
camshaft switching mechanism. The rocker arm oil control solenoid (VTEC solenoid valve), controlled by
the powertrain control module (PCM), opens and closes the oil passage, which controls VTEC operation.

The intelligent pre-driver drives the rocker arm oil control solenoid (VTEC solenoid valve) by receiving the
drive direction output at the CPU in the PCM. When the rocker arm oil control solenoid (VTEC solenoid
valve) output is OFF (low) and this condition continues for a certain time or more in response to the rocker
arm oil control solenoid (VTEC solenoid valve) ON (high) drive instruction to the intelligent pre-driver, a
malfunction is detected and a DTC is stored.

Monitor Execution, Sequence, Duration, DTC Type, OBD Status

MONITOR DESCRIPTION CHART

Execution

Continuous

Sequence

None

Duration

1.2 seconds or more

DTC Type

One drive cycle, MIL ON

OBD Status

PASSED/FAILED/NOT COMPLETED (STILL TESTING)

2007 Acura RL

2007 ENGINE PERFORMANCE Advanced Diagnostics — RL

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Friday, June 05, 2009 2:32:08 PM

Page 397 © 2005 Mitchell Repair Information Company, LLC.

Enable Conditions

ENABLE CONDITIONS

Malfunction Threshold

The return signal is OFF (low) for at least 1.2 seconds when the PCM outputs the ON (high) signal to the
rocker arm oil control solenoid (VTEC solenoid valve).

Driving Pattern

1. Start the engine. Hold the engine speed at 3,000 rpm without load (in Park or neutral) until the

radiator fan comes on.

2. Drive the vehicle in a lower gear at 4,750 rpm or more for at least 7 seconds.

Drive the vehicle in this manner only if the traffic regulations and ambient conditions allow.

Diagnosis Details

Conditions for illuminating the MIL

When a malfunction is detected, the MIL comes on and the DTC and the freeze frame data are stored in the
PCM memory.

Conditions for clearing the MIL

The MIL will be cleared if the malfunction does not recur during three consecutive trips in which the
diagnostic runs.

The MIL, the DTC, and the freeze frame data can be cleared by using the scan tool Clear command or by
disconnecting the battery.

DTC P2649 (21): ADVANCED DIAGNOSTICS (L4 ENGINE A/T)

DTC P2649: ROCKER ARM OIL CONTROL SOLENOID (VTEC SOLENOID VALVE) CIRCUIT
HIGH VOLTAGE

Condition

Minimum

Maximum

Battery voltage

10.0 V

No active DTCs

P2649

2007 Acura RL

2007 ENGINE PERFORMANCE Advanced Diagnostics — RL

me

Friday, June 05, 2009 2:32:08 PM

Page 398 © 2005 Mitchell Repair Information Company, LLC.

Fig. 312: Rocker Arm Oil Control Solenoid (VTEC Solenoid Valve) Circuit Diagram (High Voltage)

General Description

The VTEC system switches the valve timing by opening and closing the oil passage to the high/low
camshaft switching mechanism. The rocker arm oil control solenoid (VTEC solenoid valve), controlled by
the powertrain control module (PCM), opens and closes the oil passage, which controls VTEC operation.

The intelligent pre-driver drives the rocker arm oil control solenoid (VTEC solenoid valve) by receiving the
driving direction output at the CPU in the PCM. When the rocker arm oil control solenoid (VTEC solenoid
valve) output is ON (high) and this condition continues for a certain time or more in response to the rocker
arm oil control solenoid (VTEC solenoid valve) OFF (low) driving instruction to the intelligent pre-driver, a
malfunction is detected and a DTC is stored.

Monitor Execution, Sequence, Duration, DTC Type, OBD Status

MONITOR DESCRIPTION CHART

Enable Conditions

ENABLE CONDITIONS

Malfunction Threshold

The return signal is ON (high) for at least 1.2 seconds when the PCM outputs the OFF (low) signal to the
rocker arm oil control solenoid (VTEC solenoid valve).

Driving Pattern

Execution

Continuous

Sequence

None

Duration

1.2 seconds or more

DTC Type

One drive cycle, MIL ON

OBD Status

PASSED/FAILED/NOT COMPLETED (STILL TESTING)

Condition

Minimum

Maximum

Battery voltage

10.0 V

State of the engine

Running

No active DTCs

P2648

2007 Acura RL

2007 ENGINE PERFORMANCE Advanced Diagnostics — RL

me

Friday, June 05, 2009 2:32:08 PM

Page 399 © 2005 Mitchell Repair Information Company, LLC.

Start the engine, and let it idle for at least 7 seconds.

Diagnosis Details

Conditions for illuminating the MIL

When a malfunction is detected, the MIL comes on and the DTC and the freeze frame data are stored in the
PCM memory.

Conditions for clearing the MIL

The MIL will be cleared if the malfunction does not recur during three consecutive trips in which the
diagnostic runs.

The MIL, the DTC, and the freeze frame data can be cleared by using the scan tool Clear command or by
disconnecting the battery.

DTC P2A00 (157): ADVANCED DIAGNOSTICS (V6 ENGINE A/T)

DTC P2A00: REAR AIR/FUEL RATIO (A/F) SENSOR (BANK 1, SENSOR 1) CIRCUIT
RANGE/PERFORMANCE PROBLEM

Fig. 313: Rear Air/Fuel Ratio Graph

General Description

The rear air/fuel ratio (A/F) sensor (bank 1, sensor 1) has a linear signal output in relation to the oxygen
concentration. The powertrain control module (PCM) computes the air/fuel ratio from the rear A/F sensor
output voltage and uses the fuel feedback control to improve exhaust emissions. The PCM monitors the rear
A/F sensor output voltage during deceleration with the throttle fully closed, and if the output voltage
deviates greatly from normal oxygen concentration levels, it detects a malfunction and stores a DTC.

* Output to the scan tool exhibits a relationship between the rear A/F sensor output and oxygen
concentration, which is opposite to the characteristic shown in the graph. That is, a deviation toward the rich
side increases the output voltage and one toward the lean side decreases the output voltage as the
stoichiometric ratio is 0.

2007 Acura RL

2007 ENGINE PERFORMANCE Advanced Diagnostics — RL

me

Friday, June 05, 2009 2:32:08 PM

Page 400 © 2005 Mitchell Repair Information Company, LLC.

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