I have a 1999 316i the warning light for light out on instrument panel comes on intermittently.It will indicate right headlamp out or right tail lamp out.

STOP and PARK LPS will be tail lights.

ILLUM and GAUGES will.be dash lights.



STOP
Stop/CHMSL, Stoplamps

GAUGES
IP Cluster, DRL Relay, DRL Module, HDLP Switch, Keyless Entry Illumination, Low Coolant Module, CHIME Module, DRAB Module

PARK LPS
License Plate Lamp, Parking Lamps, Taillamps, Front Sidemarkers, Glove Box Ashtray

ILLUM
LP Cluster, HVAC Controls, RR HVAC Controls, IP Switches, Radio Illumination, Door Switch Illumination

Park, Tail, Marker, and License Lamps
The PARK/LAMP fuse in the instrument panel (I/P) fuse block supplies battery positive voltage to both the coil and switch sides of the PRK LAMP relay, also located in the I/P fuse block. When the headlamp switch is placed in either the PARK or HEAD position, ground is supplied to the BCM on the park lamp switch ON signal circuit. The BCM then applies a ground to the park lamp relay control circuit. This energizes the relay, applying voltage to all park, tail, marker, and license lamps. The park, tail, marker, and license lamps are also turned ON when the headlamps are commanded ON by the BCM for low light operation.
Ground for the headlamp switch is from G200. Grounds for the various lamps are as follows:
• G100 supplies the right front lamps
• G101 supplies the left front lamps
• G400 supplies the right rear lamps
• G401 supplies the left rear lamps

TAIL LAMPS, LIC LAMPS
15 AMP
PANEL DIMMING Fuse, Radio, Headlamp Switch, Instrument Cluster, Heater-A/C Control (CJ3), LR and RR Marker Lamp, LH and RH Tail/Stop/Turn Signal Lamp, LR and RR Park Lamps, Rear License Lamps
Instrument panel fuse box ,location
Fuse Block-I/P
Right side of the I/P, in the right front door opening

Back lighting or warning lights ? check engine , ABS , air bags , seat belt , oil light etc... ?
Interior Lamps Dimming
The second group includes lamps which may be dimmed. This group may use a combination of vacuum fluorescent (VF) illumination and incandescent lamps.
• Power window switches
• HVAC control head assembly
• Radio
• The instrument panel cluster (IPC)
When the ignition switch is turned to the ON position, the vacuum fluorescent (VF) display (radio) turns on at maximum brightness. When the park lamps are ON all incandescent back lighting turn ON at the dimming level indicated by the IP dimmer switch. At the same time all vacuum fluorescent (VF) displays dim to match the indicated dimming level. When the headlamp switch is placed in the PARK position, the park lamp supply voltage circuit provides an input to the body control module (BCM). The BCM then supplies voltage to the instrument panel dimmer switch through the instrument panel dimming lamps control circuit. The setting of the instrument panel dimmer switch determines the amount of voltage that the instrument panel dimmer switch supplies to the BCM through the instrument panel dimming lamps low reference circuit. The BCM then sends a pulse width modulated (PWM) voltage to all the interior lamps. All the vacuum florescent (VF) and incandescent back lighting lamps are provided a specific voltage and are then grounded. When the headlight switch is turned to the PARK or HEADLAMP position, all incandescent back lighting turn on at the dimming level indicated by the IP dimmer switch. When the IP dimmer switch is moved from MIN to MAX, all vacuum fluorescent (VF) displays, as well as all incandescent back lighting respond from Minimum intensity to maximum brightness in response to the IP dimmer switch.

I would have it checked for DTC'S - diagnostic trouble codes stored in the BCM !
DTC B2624 Display Dimming Input Range/Performance
The body control module (BCM) supplies voltage to the instrument panel dimmer switch through the instrument panel dimmer switch signal circuit. The dimmer switch varies the voltage and returns the new voltage to the BCM through the dimmer switch signal return circuit. The BCM uses this voltage to determine the illumination level of the instrument panel lamps.

DTC B2625 Display Dimming Pulse Width Modulation (PWM) Output Circuit Range/Performance
The body control module (BCM) receives a variable voltage from the instrument panel (I/P) lamp dimmer switch. The BCM uses this signal in order to vary the illumination level of the I/P lamps. The I/P dimming lamps output from the BCM is a pulse width modulated voltage supply used to light the I/P lamps. If a malfunction occurs in the I/P dimming lamps output circuit, this DTC is set.

DTC B2662 Park Lamp Switch Circuit Malfunction
The park lamps are controlled by the turn/headlamp switch. Positive battery voltage is supplied to the switch through the EXT LP fuse. When the turn/headlamp switch is placed in the park or head position, battery voltage is supplied to the park lamps. The body control module (BCM) is also connected to the park lamp circuit to sense whether or not the park lamps turn ON when the low beam or high beam headlamps are turned ON. The BCM also uses the parklamp battery positive voltage to power the instrument panel (I/P) dimmer output circuit. If the BCM senses that the low beam or high beam headlamps are ON and the park lamp input is not active, DTC B2662 sets.
Do the park lamps work ?

Turn the parking lamps or headlamps on in order to illuminate the instrument panel and instrument panel cluster lamps. Voltage applies at all times through the TAIL fuse to the tail relay. Turning the turn signal/headlamp switch to the PARK or the HEAD position provides a ground path to the coil side of the relay to G202. The ground path energizes the coil of the relay. This closes the contacts in the relay. The closed contacts apply voltage to the IP dimmer illumination controller and all the illumination lamps. The illumination lamps are ground through the illumination controller. The controller is located on the left side of the instrument panel. Since the illumination controller is ground to G200, the lamps illuminate when voltage applies. The intensity of the instrument panel and the instrument panel cluster lamps is adjusted by the controller (4). The controller controls the intensity of the lamps by controlling the amount of current from the lamps to ground.Check the tail relay !

Go to http://www.bbbind.com/free_tsb.html free wiring diagrams ! You having tail light problems ? Do you know how they work ?

They are turned on by the BCM !
Park, Tail, Marker and License Lamps
The park, tail, license, and marker lamps are turned ON when the headlamp switch is placed in either the HEAD or PARK lamp positions, or anytime the automatic light control (ALC) turns the headlamps ON. When the headlamp switch is placed in the park lamp or headlamp positions, ground from G202 is applied through the signal circuit to the BCM indicating the park lamp request. In response to this signal, the BCM applies ground through the park lamp relay control circuit energizing the PARK LP PCB Relay. With the relay energized, battery voltage is applied through the switch side of the relay, both park lamp fuses, and the supply voltage circuits illuminating the park, tail marker, and license lamps. Ground for the left front park and marker lamps is provided at G101 and the right front park and marker lamps at G100. Ground for all rear lamps is provided at G302.
Turn Signal Lamps
The LT T/SIG and RT T/SIG fuses located in the underhood fuse block supplies battery positive voltage to the body control module (BCM) for turn signal and hazard lamp operation. When the turn signal switch is place in either the LEFT or RIGHT position, ground from G202 is applied through the turn signal switch signal circuit to the BCM indicating the turn signal request. In response to this signal, the BCM applies a pulsating voltage to the front and rear turn signal lamps supply voltage circuits cycling the lamps ON and OFF. The BCM also sends a message via GMLAN to the instrument panel cluster (IPC) to cycle the turn signal indicator ON and OFF depending on the position of the turn signal switch.
Ground for the turn signal lamps is supplied as follows:
?€¢
G101 provides ground for the left front turn signal lamp

?€¢
G100 provides ground for the right front turn signal lamp

?€¢
G302 provides ground for the left and right rear turn signal lamps

Park lamp fuse 20amp located in the under hood fuse box .DRL control module
Daytime Running Lamps (DRL) Control Module
Right of the steering column, behind the IP
Park, Sidemarker, Tail and License Lamps
Voltage is applied continuously to the PARK fuse to the headlamp and the instrument panel (IP) lamp dimmer switch through CKT 1340.
When the headlamp and the (IP) lamp dimmer switch is in the PARK or HEAD position, voltage is applied to CKT 9 thus activating the following lamps:
• The park lamps
• The side marker lamps
• The tail lamps
• The license lamps
The park/turn lamps are the only lamps that do not activate yet receive a current from CKT 9. The park/turn lamps do not activate because the voltage drop across the front side marker lamps is much higher than that across the turn lamp filaments Step
Action
Normal Result(s)
Abnormal Result(s)*

1
Turn the headlamp/instrument panel (IP) lamp dimmer switch to the PARK position.
The following lamps light:
• The license plate lamps
• The taillight lamps
• The front side marker lamps (Domestic)
• The front parking lamps (Domestic)
The headlamp position lamps (Export)
Refer to Park Lamps Inoperative
Park Lamps Inoperative
Step
Action
Value(s)
Yes
No

1
Inspect the PARK LP fuse.
Is the fuse open?
--
YES - Go to Step 2
NO - Go to Step 3

2
Repair a short to ground in CKT 1340.
Is the repair complete?
--
Go to Exterior Lights System Check
--

3
Turn the headlamp/instrument panel (IP) lamp dimmer switch to the PARK position.
Use a test light in order to backprobe the headlamp/IP lamp dimmer switch harness connector between terminal R and ground.
Did the test lamp light?
--
Go to Step 7
Go to Step 4

4
Use a test light in order to backprobe the headlamp/IP lamp dimmer switch harness connector between terminal O and ground.
Did the test lamp light?
--
Go to Step 5
Go to Step 6

5
Replace the headlamp/IP lamp dimmer switch. Refer to Headlamp Switch Replacement .
Is the repair complete?
--
Go to Exterior Lights System Check
--

6
Repair the following conditions in CKT 1340 between the PARK LP fuse and the headlamp and the IP lamp dimmer switch harness connector terminal O:
• A faulty connection
• An open circuit
Is the repair complete?
--
Go to Exterior Lights System Check
--

7
Repair the following conditions in CKT 9 between the headlamp and the IP lamp dimmer switch harness connector terminal R and S204:
• A faulty connection
• An open circuit
Is the repair complete?
--
Go to Exterior Lights System Check

I have the same problem few days ago, and still didn't find any solution. Can any one please help?????18