Increasing the Dome Light Delay

By Christopher Hapeman (cjh@garage.att.com) Copyright © CCA

Procedure for increasing the delay of the dome light. after shutting the door(s), in my '90 corrado the stock delay is 5 secs. Total work time: approx. 30 mintues.

pry out the dome/map light module
it will now be hanging by 5 wires which are joined to a connector
remove the connector from the dome/map light module by pushing in the connector clip and pulling it off. now the dome/map module can be removed from the car.
lay the module with the lens side down...pry off the protective sheet, it is only held on with tabs and slots.
now you are looking at the circuit with the component side down... Carefully remove the circuit board by releasing the three tabs, at the same time you must pry off the bronze connectors which are located on the bottom side of the circuit board...there are two sets, one for the dome light switch and the other for the map light switch They are interlocked U shaped connectors, you will prying metal from metal ... NOT metal from plastic

lay the circuit board with the component side up (bulbs facing up), the dome light switch's three bronze connectors will be on the upper left and the map light's two bronze connectors will be on the upper right...


   +----------------------+                        +----------------------+
   |     U   U   U        |                        |    U   U             |
   |               hella  |                        |             B2326    |
   |                      +------------------------+                      |
   |                                                                  c1  |
   | |    \ /                    | | |    ----     - r -    |  |     + -  |
   | d     X    |  B             | | |    ----    - d -  |  r  r     ---  | 
   | |    / \   |                | | |    ----           |  |  |    | C |<---+
   |            |     U                                  |          |   | |  |
   | |                                    X      bulb       |  |     ---  |  |
   | r                   L       - c -                      r  r   |  |   |  |
   | |     X                                                |  |   d  r   |  |
   |                        B    - c -   X                         |  |   |  |
   |                                                                      |  |
   +----------------------------------------------------------------------+  |
                                                                             |
  U     : bronze U shaped switch connectors                                  |
                                                                             | 
  - d - : diode                              ---                             |
                                            | C |  : capacitor to swap ------+
  - r - : resistor                          |   | 
                                             ---
  - c - : capacitor

    X   : transistor

identify the capacitor which is responsible for the dome light delay, it is the far top right capacitor labeled C1 and is the only component on the board with + and - leads labeled. my stock one was wrapped in blue with 35V 22uF written on it.
When current is sent to the module (ie. a door is opened) the dome bulb is lit and current is also sent to and stored in this capacitor...when current is cut (ie. a door is closed) the stored current in this capacitor is released allowing the light to remain lit until the stored current is exhausted...
Swapping in a capacitor of a larger value, greater uF (or MFD), allows for more current to be stored which allows the light to remain lit longer.
radio shack has capacitors for < $1US, you are looking for an electrolytic capacitor with radial leads, 35WVDC. i used one with 47MFD, thus doubling the stock 22MFD...my dome light now stays lit for approximately 12 secs. after the doors are shut. you could get a capacitor with about 70MFD making the delay about 20 seconds. this triples the stock component, i don't think you should go much higher than this since you might damage other components on the board.

NOTE: make sure you match the - and + leads of the new capacitor with the - and + labels on the circuit board

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