B1663

B1663-REAR FOG LAMP CONTROL CIRCUIT LOW

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 low condition on the (L899) Rear Fog Lamp Signal Control circuit.





Diagnostic Test

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

Does the scan tool display DTC: B1663-REAR FOG LAMP CONTROL CIRCUIT LOW?

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. ATTEMPT TO SET THE OPPOSITE DTC
1. Turn the Rear Fog Lamps off.
2. Turn the ignition off.
3. Disconnect the Left and Right Rear Fog Lamp harness connectors.
4. Turn the ignition on.
5. Turn the Rear Fog Lamps on.
6. With the scan tool, read DTCs.

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

Yes

- Determine which lamp is causing the short to ground condition. Replace the appropriate Rear Fog Lamp Bulb.
- Perform the BODY VERIFICATION TEST. Body Verification Test.

No

- Go To 3

3. CHECK THE (L899) REAR FOG LAMP SIGNAL CONTROL CIRCUIT FOR A SHORT TO GROUND
1. Turn the ignition off.
2. Disconnect the TIPM C7 harness connector.
3. Measure the resistance between ground and the (L899) Rear Fog Lamp Signal Control circuit.

Is the resistance above 10k Ohms?

Yes

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

No

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