P0646

P0646-LOW VOLTAGE DETECTED AT THE A/C CLUTCH RELAY





For complete wiring diagrams refer to Diagrams/Electrical.


- When Monitored:

When the ignition is on.

- Set Condition:

When the signal from the A/C Clutch circuit output does not match the signal from the A/C Clutch feedback







Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding.

Diagnostic Test


1. TIPM GROUND OPEN

Ignition on, engine not running.

Using a voltmeter, connect one voltmeter lead to Battery Positive and the other on TIPM ground.

Does the voltmeter show battery voltage?

Yes

- Go To 2

No

- Fix or replace the open circuit in the Battery Return Circuit
- Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test

2. LOOSE CONNECTION

Disconnect the ECM and TIPM connectors.


NOTE: Check connectors - Clean/repair as necessary.

Using an Ohmmeter, measure the resistance of the A/C Clutch signal wire between the TIPM and the ECM connector.

Is the resistance less than 10 Ohms?

No

- Fix or replace the harness.
- Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test

Yes

- Go To 3

3. A/C CLUTCH CIRCUIT OPEN

Turn the ignition off.

Using an Ohmmeter, measure the resistance of the A/C Clutch signal wire between the TIPM connector and battery negative.

Is the resistance greater than 100k Ohms?

Yes

- Go To 4

No

- Fix or replace the harness.
- Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test

4. FUSED BATTERY SUPPLY

Connect the ECM and TIPM connectors.

Ignition on, engine not running.

Using a back probing tool 6801, back probe the A/C clutch logic pin in the TIPM logic connector.

Using a 12 volt test light connected to battery positive, check the transmission logic circuit at the TIPM connector while actuating the A/C clutch circuit with the Electronic Service Tool.


NOTE: The test light must illuminate brightly.

Compare the brightness to that of a direct connection to the battery.

Does the test light illuminate brightly?

Yes

- Go To 5

No

- Replace the ECM.
- Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test

5. TIPM

Using a back probing tool, back probe the A/C clutch power pin from the TIPM power connector.

Using a 12 volt test light connected to battery positive, check the transmission power circuit at the TIPM connector while actuating the A/C clutch circuit with the Electronic Service Tool.


NOTE: The test light must illuminate brightly.

Compare the brightness to that of a direct connection to the battery.

Does the test light illuminate brightly?

Yes

- Test complete.
- Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test

No

- Replace the TIPM.
- Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test