KM: A/C Clutch Relay, A/C Circuits

KM: Introduction See: KM: A/C Clutch Relay, A/C Circuits - Introduction

KM1 KOEO/KOER DTC P1460: VERIFY ACCS PID IS OFF

Note: Verify A/C and defrost were off during KOEO/KOER Self-Tests. If the vehicle is not equipped with A/C, the WOT A/C Cutoff (WAC) circuit is not used and the DTC P1460 can be ignored.

• Start engine.
• A/C and defroster off.
• Access ACCS PID.

Is the ACCS PID off?
Yes

• KEY OFF. GO to KM2

.

No

• ACCS input to PCM is requesting A/C. REFER to the Heating and Air Conditioning to diagnose symptom (A/C always on).

KM2 CHECK VPWR VOLTAGE TO A/C CLUTCH RELAY

• Disconnect A/C clutch relay.
• Key on, engine off.
• Measure VPWR circuit voltage at the A/C clutch relay harness connector.

Is voltage greater than 10.5 volts?
Yes

• KEY OFF. GO to KM3

.

No

• For LS6/LS8

:

• GO to B5 See: B: Electronic Engine Control (EC) Power Relay - Pinpoint Test

.

• All others

:

• REPAIR open circuit. START engine. Turn A/C on, WAIT 15 seconds. A/C off. RERUN Quick Test.

KM3 CHECK A/C CLUTCH RELAY

• Refer to pin numbers molded on A/C clutch relay. There will be either a Pin 1 or Pin 85.
• Measure resistance between either Pin 1 or Pin 85 and all other pins of the A/C clutch relay. One measurement must be between 40 and 120 ohms, with the other measurements being greater than 10,000 ohms.

Are all resistance checks OK?
Yes

• GO to KM4

.

No

• REPLACE A/C clutch relay. START engine. TURN A/C on, WAIT 15 seconds. A/C off. RERUN Quick Test.

KM4 CHECK WAC CIRCUIT FOR SHORT TO POWER IN HARNESS

• Disconnect PCM.
• Key on, engine off.
• Measure voltage between WAC circuit at A/C clutch relay vehicle harness connector and ground.

Is voltage less than 1.0 volt?
Yes

• KEY OFF. GO to KM5

.

No

• REPAIR short circuit. START engine. Turn A/C on, WAIT 15 seconds. A/C off. RERUN Quick Test.

KM5 CHECK WAC CIRCUIT FOR SHORT TO GROUND IN HARNESS

• Disconnect scan tool from DLC.
• Measure resistance between WAC circuit at A/C clutch relay vehicle harness connector and ground.

Is resistance greater than 10,000 ohms?
Yes

• GO to KM6

.

No

• REPAIR short circuit. START engine. Turn A/C on, WAIT 15 seconds. A/C off. RERUN Quick Test.

KM6 CHECK WAC CIRCUIT FOR OPEN IN HARNESS

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

• Measure resistance of WAC circuit between PCM harness connector and the A/C clutch relay harness connector.

Is resistance less than 5.0 ohms?
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). START engine. Turn A/C on, WAIT 15 seconds. A/C off. RERUN Quick Test.

No

• REPAIR open circuit. START engine. Turn A/C on, WAIT 15 seconds. A/C off. RERUN Quick Test.

KM10 ACCS PID OFF WITH A/C ON: VERIFY A/C CLUTCH IS GETTING POWER

• Start engine.
• While listening for A/C clutch to engage, turn A/C on (if clutch cannot be heard, disconnect A/C clutch and connect a non-powered test lamp to A/C clutch PWR and ground circuit to check for power).

Does the A/C clutch engage (or the light turn on)?
Yes

• Power is getting to A/C clutch, but ACCS PID is OFF. GO to KM11

.

No

• The ACCS PID is OFF because power is not getting to the A/C clutch. This is not a cause of the low idle symptom. RETURN to Section 3 See: Symptom Related Diagnostic Procedures to continue low idle diagnosis, or REFER to the Heating and Air Conditioning to diagnose A/C system concerns.

KM11 CHECK ACCS CIRCUIT FOR OPEN IN HARNESS

• Disconnect PCM.
• Disconnect A/C clutch.
• Measure resistance between Pin 41 at the PCM harness connector and the A/C clutch power circuit at the A/C clutch harness connector.

Is resistance less than 5.0 ohms?
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).

No

• REPAIR open circuit.

KM19 DTC P1464: CHECK ACCS PID

Note: Verify A/C and defrost were off during Self-Test. If A/C or defrost were on, turn off and rerun Self-Test.

• Key on, engine off.
• A/C and defrost off.
• Access ACCS PID.

Is ACCS PID on?
Yes

• E-Series (except 4.2L):
• GO to KM20

.

• All others:
• ACCS input to PCM is requesting A/C. REFER to the Heating and Air Conditioning to diagnose symptom (A/C always on).

No

• The ACCS PID indicates that the ACCS input to the PCM is low. VERIFY

test results. With A/C and defrost off, RERUN Self-Test where P1464 was
received.

KM20 ACCS PID ON: DISCONNECT A/C CYCLING SWITCH AND CHECK IF ACCS PID TURNS OFF

• Disconnect A/C cycling switch.
• Key on, engine off.
• Access ACCS PID.

Is ACCS PID off?
Yes

• VERIFY operation of A/C demand switch. REFER to the Heating and Air Conditioning. If OK, REPAIR short to power in A/C Demand circuit to A/C cycling switch.

No

• KEY OFF. GO to KM21

.

KM21 CHECK ACCS CIRCUIT FOR SHORT TO POWER IN HARNESS

• Disconnect PCM.
• Key on.
• Measure voltage between PCM harness connector pin 41 and ground.

Is voltage less than 1.0 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).

No

• REPAIR short circuit.

KM30 CONTINUOUS MEMORY DTC P1460: CHECK WAC CIRCUIT FOR INTERMITTENT SHORT TO GROUND

Note: If the vehicle is not equipped with A/C, the WAC circuit is not used and the P1460 can be ignored.
Note: Refer to the beginning of this pinpoint test for PCM pin numbers.

• Key on, engine off.
• Check WAC circuit for short to ground while completing the following (the A/C clutch will click on when a fault is detected):
• Shake, wiggle and bend the WAC circuit between the PCM and the A/C clutch relay.
• Lightly tap on the A/C clutch relay (to simulate road shock).

Is a fault indicated?
Yes

• KEY OFF. ISOLATE fault and REPAIR as necessary. CLEAR the DTCs. START

engine. Turn A/C on, WAIT 15 seconds. A/C off. RERUN Quick Test.

No

• GO to KM31

.

KM31 CHECK WAC CIRCUIT FOR INTERMITTENT OPEN OR SHORT TO POWER

• Key on, engine off.
• Access Output Test Mode on scan tool.
• Turn outputs on.
• Check WAC circuit for open or short to power while completing the following (the A/C clutch will click off when a fault is detected):
• Shake, wiggle and bend the WAC circuit between the PCM and the A/C clutch relay.
• Shake, wiggle and bend the VPWR circuit to the A/C clutch relay.
• Lightly tap on the A/C clutch relay (to simulate road shock).

Is a fault indicated?
Yes

• KEY OFF. ISOLATE fault and REPAIR as necessary. CLEAR the DTCs. START

engine. Turn A/C on, WAIT 15 seconds. A/C off. RERUN Quick Test.

No

• KEY OFF. Unable to duplicate or identify fault at this time. GO to Z1 See: Diagnostic Trouble Code Tests and Associated Procedures\SECTION 5: Pinpoint Tests\Z: Intermittent - Pinpoint Test

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