F 250 2WD LD Pickup V8-4.6L SOHC VIN 6 (1997)
Interior Lighting Module: Testing and Inspection
Flow of Diagnosis
1. The interior lighting system is a Generic Electronic Module (GEM) or Central Timer Module (CTM) controlled system.
2. Verify the customer concerns by operating the interior lamps.
3. Visually inspect for obvious signs of mechanical and electrical damage:
VISUAL INSPECTION CHART
MECHANICAL
^
Switch(es)
ELECTRICAL
^
Fuse(s)
^
Damaged wiring harness
^
Loose or corroded connector(s)
^
Circuitry
^
Damaged bulb(s)
4. If the concern is not visually evident, determine the symptom and proceed to the Symptom Chart. See: Symptom Related Diagnostic Procedures
Initial Inspection and Diagnostic Overview
1. The interior lighting system is a Generic Electronic Module (GEM)/Central Timer Module (CTM) controlled system.
2. Verify the customer concerns by operating the interior lamps.
3. Visually inspect for obvious signs of mechanical and electrical damage:
VISUAL INSPECTION CHART
MECHANICAL
^
Switch(es)
ELECTRICAL
^
Fuse(s)
^
Damaged wiring harness
^
Loose or corroded connector(s)
^
Circuitry
^
Damaged bulb(s)
4. If the concern is not visually evident, determine the symptom and proceed to the Symptom Chart. See: Symptom Related Diagnostic Procedures
Reading and Clearing Diagnostic Trouble Codes
Diagnostic Trouble Code (DTC)s are erased when the diagnostic mode is exited if the ignition switch has been moved to the START position any time
during the diagnostic test mode. DTCs are also erased when power is removed from the Central Timer Module.
Diagnostic Trouble Coded (DTCs)
The entire set of stored Diagnostic Trouble Codes (DTCs) will be repeated indefinitely until either the Input Test mode is entered or the ground is
removed from the diagnostic input. Refer to the Central Timer Module (CTM) Diagnostic Trouble Code (DTC) chart for all possible interior lighting
(CTM controlled) DTCs. See: Diagnostic Trouble Code Descriptions/Central Timer Module Diagnostic Trouble Code Chart
Diagnostic Trouble Code Output Mode
When the Central Timer Module (CTM) is in the normal mode of operation it is continually monitoring itself. When a concern occurs that the CTM can
recognize, it is recorded.
The Diagnostic Trouble Code (DTC) Output mode outputs DTCs by sounding the chime. This mode is entered from the input test mode when the key is
removed from the ignition switch. These DTCs may then be used to help diagnose hard faults and/or intermittent failures. Such failures will often be
observed by the vehicle owner while the vehicle is on the road but may not occur when the vehicle is being repaired.
Tone and Door Ajar Indicator Test Mode
