B1664

B1664-REAR FOG LAMP CONTROL CIRCUIT HIGH

For a complete wiring diagram, refer to the Wiring Information.

Theory of Operation

The Totally Integrated Power Module (TIPM) receives a bus message requesting rear fog lamp illumination. When this bus message is received, the TIPM provides a voltage output through the rear fog lamp control output circuit. The rear fog lamp control output circuit connects to the both the Left and Right Rear Fog Lamps. Separate ground circuits are used for the Left and Right Rear Fog Lamps.

- When Monitored:
With the rear fog lamps active.

- Set Condition:
When the Totally Integrated Power Module (TIPM) detects a high condition on the (L899) Rear Fog Lamp Signal Control circuit.





1. INTERMITTENT CONDITION
1. Turn the ignition on.
2. With the scan tool, clear all TIPM DTCs.
3. Turn the Rear Fog Lamps on.
4. With the scan tool, read DTCs.

Does the scan tool display DTC: B1664-REAR FOG LAMP CONTROL CIRCUIT HIGH?

Yes

- Go To 2

No

- Test complete, the condition or conditions that originally set this DTC are not present at this time. Using the wiring diagrams as a guide, check all related splices and connectors for signs of water intrusion, corrosion, pushed out or bent terminals, and correct pin tension.
- Perform the BODY VERIFICATION TEST. Body Verification Test.

2. CHECK THE (L899) REAR FOG LAMP SIGNAL CONTROL CIRCUIT FOR A SHORT TO VOLTAGE IN THE HARNESS
1. Turn the Rear Fog Lamps off.
2. Turn the ignition off.
3. Disconnect the Left and Right Rear Fog Lamp harness connectors.
4. Disconnect the TIPM C7 harness connector.
5. Turn the ignition on.
6. Measure the voltage between ground and the (L899) Rear Fog Lamp Signal Control circuit.

Is there any voltage present?

Yes

- Repair the short to voltage on the (L899) Rear Fog Lamp Signal Control circuit.
- Perform the BODY VERIFICATION TEST. Body Verification Test.

No

- Go To 3

3. CHECK THE REAR FOG LAMPS FOR CORRECT OPERATION
1. Turn the ignition off.
2. Reconnect the TIPM C7 harness connector.
3. Connect a 12-volt test light between the (L899) Rear Fog Lamp Signal Control circuit and the (Z910) Ground circuit at the Left Rear Fog Lamp harness connector.
4. Turn the ignition on.
5. Turn the Rear Fog Lamps on.

Does the test light illuminate brightly?

Yes

- Replace the Left and Right Rear Fog Lamp Bulb.
- Perform the BODY VERIFICATION TEST. Body Verification Test.

No

- Go To 4

4. CHECK THE (L899) REAR FOG LAMP SIGNAL CONTROL CIRCUIT FOR AN OPEN IN THE HARNESS
1. Turn the ignition off.
2. Disconnect the TIPM C7 harness connector.
3. Measure the resistance of the (L899) Rear Fog Lamp Signal Control circuit between the Left Rear Fog Lamp harness connector and the TIPM C7 harness connector.

Is the resistance below 5.0 Ohms?

Yes

- Go To 5

No

- Repair the open in the (L899) Rear Fog Lamp Signal Control circuit.
- Perform the BODY VERIFICATION TEST. Body Verification Test.

5. CHECK THE (Z910) GROUND CIRCUITS FOR AN OPEN IN THE HARNESS
1. Using a 12-volt test light connected to 12-volts, check the (Z910) Ground circuit at the Left Rear Fog Lamp harness connector.
2. Using a 12-volt test light connected to 12-volts, check the (Z910) Ground circuit at the Right Rear Fog Lamp harness connector.

Does the test light illuminate brightly for each circuit?

Yes

- Replace the Totally Integrated Power Module (TIPM).
- Perform the BODY VERIFICATION TEST. Body Verification Test.

No

- Repair the open in the (Z910) Ground circuits.
- Perform the BODY VERIFICATION TEST. Body Verification Test.