DG: Knock Sensor (KS)

DG: Introduction See: Diagnostic Trouble Code Tests and Associated Procedures\SECTION 5: Pinpoint Tests\DG: Knock Sensor (KS) - Introduction

DG1 DTC P0330, P0331 (KS2), DTC P0325, P0326 (KS1): CHECK VOLTAGE BETWEEN SENSOR AND SIG RTN

• Verify that KS is connected and installed properly. Then complete comprehensive repair verification drive cycle. Refer to Section 2, Drive Cycles See: Diagnostic Trouble Code Tests and Associated Procedures\SECTION 2: Diagnostic Methods\Drive Cycles.
• Key on, engine off.
• Access KS PID.
• Read dc voltage.

Is the KS PID less than 0.5 volts?
Yes

• KEY OFF. GO to DG2

.

No

• GO to DG5

.

DG2 CHECK KS SENSOR RESISTANCE

Note: Refer to the PCM connector pin numbers in the beginning of this pinpoint test.

• Disconnect KS, measure resistance through the KS harness connector pins
• For 4.2L: Measure resistance between (KS+) and (KS-) at the knock sensor.

Is resistance between 4.39 and 5.35 megaohms?
Yes

• For Town Car, 5.4L E/F-Series (HD), and 6.8L

E/F-Series:

• GO to DG6

.

• All others:
• GO to DG7

.

No

• For resistance greater than 5.35 megaohms:
• GO to DG3

.

• For resistance less than 4.39 megohm:
• GO to DG4

.

DG3 CHECK FOR OPEN OF KS CIRCUIT BETWEEN KS SIGRTN AND SHIELD IN HARNESS

• Disconnect PCM.
• Measure resistance of the KS+ circuit between the PCM harness connector pin and the KS harness connector.
• For 4.2L:
• Measure resistance of KS- circuit between the PCM harness connector pin and the KS connector.
• Where applicable, measure resistance of shield between the PCM harness connector and the shield pin at the KS connector.

Is each resistance less than 5.0 ohms?
Yes

• REPLACE KS.

No

• REPAIR open circuit. COMPLETE Comprehensive Component Repair

Verification Drive Cycle. (REFER to Section 2, Drive Cycles See: Diagnostic Trouble Code Tests and Associated Procedures\SECTION 2: Diagnostic Methods\Drive Cycles)

DG4 CHECK KS CIRCUIT FOR SHORT TO GROUND IN HARNESS

• Disconnect PCM.
• Measure resistance between the KS- circuit at the PCM harness connector and chassis GND.
• Measure resistance between the KS+ circuit at the PCM harness connector and chassis GND.
• For 4.2L Only:
• Measure resistance between the KS- and KS+ at the PCM harness connector.

Is each resistance greater than 10,000 ohms?
Yes

• GO to DG7

.

No

• SERVICE short circuit. COMPLETE Comprehensive Component Repair

Verification Drive Cycle. (REFER to Section 2, Drive Cycles See: Diagnostic Trouble Code Tests and Associated Procedures\SECTION 2: Diagnostic Methods\Drive Cycles.)

DG5 CHECK KS CIRCUITS FOR SHORT TO POWER IN HARNESS

• Disconnect PCM.
• Key on.
• Measure voltage between the KS+ circuit at the PCM harness connector and battery negative post.
• For 4.2L Only:
• Measure voltage between the KS- circuit at the PCM harness connector and battery negative post.

Is each voltage less than 0.5 volt?
Yes

• REPLACE PCM (refer to Section 2, Flash Electrically Erasable Programmable Read Only Memory (EEPROM) See: Programming and Relearning\Flash Electrically Eraseable Programmable Read Only Memory - Flash EEPROM).

COMPLETE Comprehensive Component Repair Verification Drive Cycle. (REFER to
Section 2, Drive Cycles See: Diagnostic Trouble Code Tests and Associated Procedures\SECTION 2: Diagnostic Methods\Drive Cycles.)

No

• SERVICE short circuit. COMPLETE Comprehensive Component Repair

Verification Drive Cycle. (Refer to Section 2, Drive Cycles See: Diagnostic Trouble Code Tests and Associated Procedures\SECTION 2: Diagnostic Methods\Drive Cycles.)

DG6 CHECK SHIELD CIRCUIT RESISTANCE

• Disconnect PCM.
• Measure resistance of the KS shield between the PCM harness connector pin and the KS harness connector.

Is resistance less than 5.0 ohms?
Yes

• GO to DG7

0. COMPLETE Comprehensive Component Repair Verification Drive Cycle. (REFER to Section 2, Drive Cycles See: Diagnostic Trouble Code Tests and Associated Procedures\SECTION 2: Diagnostic Methods\Drive Cycles.)

No

• REPAIR open circuit. COMPLETE Comprehensive Component Repair

Verification Drive Cycle. (REFER to Section 2, Drive Cycles See: Diagnostic Trouble Code Tests and Associated Procedures\SECTION 2: Diagnostic Methods\Drive Cycles.)

DG7 CHECK PCM FOR SHORT TO GROUND

• Measure resistance between KS+ and SIG RTN circuits at the KS harness connector.
• For 4.2L Only:
• Measure resistance between KS+ and KS- circuits at the PCM harness connector.

Is resistance greater than 10,000 ohms?
Yes

• REPLACE KS. If concern is still present, REPLACE PCM (refer

to Section 2, Flash Electrically Erasable Programmable Read Only Memory (EEPROM) See: Programming and Relearning\Flash Electrically Eraseable Programmable Read Only Memory - Flash EEPROM).
COMPLETE Comprehensive Component Repair Verification Drive Cycle. (REFER to
Section 2, Drive Cycles See: Diagnostic Trouble Code Tests and Associated Procedures\SECTION 2: Diagnostic Methods\Drive Cycles.)

No

• REPLACE PCM (refer to Section 2, Flash Electrically Erasable Programmable Read Only Memory (EEPROM) See: Programming and Relearning\Flash Electrically Eraseable Programmable Read Only Memory - Flash EEPROM).

COMPLETE Comprehensive Component Repair Verification Drive Cycle. (REFER to
Section 2, Drive Cycles See: Diagnostic Trouble Code Tests and Associated Procedures\SECTION 2: Diagnostic Methods\Drive Cycles.)

DG15 DTC P0325, P0326 (KS1), DTC P0330, P0331 (KS2): CHECK KS SENSOR VOLTAGE

Note: Refer to the PCM connector pin numbers in the beginning of this pinpoint test.

• Access KS PID.
• Key on, engine off.

Is the KS PID between 2.2 and 2.6 volts?
Yes

• KEY OFF. GO to DG16

.

No

• GO to DG18

.

DG16 CHECK KS CIRCUIT FOR INTERMITTENT FAULT

• Key on.
• While viewing the voltmeter, grasp the vehicle harness as close to the knock sensor(s) as possible. Shake and bend a small section of the harness from the KS sensor to the PCM.
• Tap the PCM and KS connectors if possible.

Is KS reading changing?
Yes

• ISOLATE fault and SERVICE as required. COMPLETE Comprehensive

Component Repair Verification Drive Cycle. (REFER to Section 2, Drive Cycles See: Diagnostic Trouble Code Tests and Associated Procedures\SECTION 2: Diagnostic Methods\Drive Cycles
.)

No

• GO to DG17

.

DG17 CHECK FOR KS VOLTAGE INCREASE

• Start and run engine.
• Monitor voltage at the knock sensor at idle and at 3000 rpm.

Does the AC voltage reading increase?
Yes

• For symptom only: RETURN to Section 3. See: Symptom Related Diagnostic Procedures
• All others with DTC:
• REPLACE PCM (refer to Section 2, Flash Electrically Erasable Programmable Read Only Memory (EEPROM) See: Programming and Relearning\Flash Electrically Eraseable Programmable Read Only Memory - Flash EEPROM).

COMPLETE Comprehensive Component Repair Verification Drive Cycle. (REFER to
Section 2, Drive Cycles See: Diagnostic Trouble Code Tests and Associated Procedures\SECTION 2: Diagnostic Methods\Drive Cycles.)

No

• GO to DG18

.

DG18 CHECK KS CIRCUIT FOR OPEN IN HARNESS

• PCM disconnected.
• Disconnect suspect KS.
• Measure resistance of the KS+ signal circuit between the PCM harness connector pin and the KS harness connector.
• Measure resistance of the SIG RTN circuit between the PCM harness connector and the KS harness connector.

Is each resistance less than 5.0 ohms?
Yes

• GO to DG19

.

No

• REPAIR open circuit. COMPLETE Comprehensive Component Repair

Verification Drive Cycle. (REFER to Section 2, Drive Cycles See: Diagnostic Trouble Code Tests and Associated Procedures\SECTION 2: Diagnostic Methods\Drive Cycles.)

DG19 CHECK KS CIRCUIT FOR SHORT TO GROUND

• Measure resistance of the KS+ circuit between the PCM harness connector pin and chassis GND.

Is resistance greater than 10,000 ohms?
Yes

• REPLACE suspect KS. COMPLETE Comprehensive Component Repair

Verification Drive Cycle. (REFER to Section 2, Drive Cycles See: Diagnostic Trouble Code Tests and Associated Procedures\SECTION 2: Diagnostic Methods\Drive Cycles.)

No

• REPAIR short circuit. COMPLETE Comprehensive Component Repair

Verification Drive Cycle. (REFER to Section 2, Drive Cycles See: Diagnostic Trouble Code Tests and Associated Procedures\SECTION 2: Diagnostic Methods\Drive Cycles.)