Angry Kitchen Appliances: Information on Saab 9-5 headlights modification

Information on Saab 9-5 headlights modification

Background
A Warning
Description
Schematics
A Warning
Links

Background

The switch between high beam and low beam is done in two steps in the 9⁵, step 1 gives a high beam flash, step 2 switches between low and high beam (if the light switch is in the right position). This design makes the transition between high beam and low beam take too long time as the stalk has to pass step 0 -> 1 -> 2 -> 1 -> 0 before the high beam goes out. Compare this to the Saab 9000, with only one step, where the same operation is quicker as the stalk only has to pass step 0 -> 1 -> 0.

For those who are, as I was, irritated on how the high beam and low beam switching works in the 9⁵, I have done a schematics showing the modifications that I have done to my 9⁵ (MY 1999) so that

Switch between high and low beam works as in Saab 9000.
Reduced low beam for longer bulb life.
Reduced low beam when high beam in on for better distance visibility.

The modification for the high/low switch and the reduced low beam is independent and can be done separately. The modification does not draw any current through the stalk switch, as Saab do. Instead it uses a relay. Has Saab forgotten the result of that design with the early Saab 9000 models up until model year 1987?

A Warning

Don't even think about doing these modifications unless you know what you are doing.
Don't blame me if you damage your cars electrical system.

Description

This modification is not easy, so if you feel uncertain about it then do not try it. The modifications requires a visit under the steering wheel, behind the light switch, and in the relay box by the battery. Note that the schematics show connections and cable colours for the EU version of model year 1999. Connections and cable colours varies between markets and model years. Different model years may be connected differently, but 1998 to 2001 should be similar. For model year 2002 these changes can't be appropriate, large changes must have been introduced to handle the BiXenon lights, and BiXenon does not lend itself to reduced low beam anyway.

Schematics

(16kB)

Schematics showing two modifications, how switch between high and low beam is modified to work like the Saab 9000, and reduced low beam for longer bulb life (download pdf (16kB)).

The notes in the pdf file are in Swedish, a translation is available.

The ballast resistor I used for the reduced low beam is a ARCOL type HS 50, 0.33 ohm. I mounted the resistor on a piece of aluminium/aluminum so it can withstand the power dissipation.

A Warning

An important comment about the reduced low beam is that the resistor gets hot and it is not adviceable to place it inside the relay box. As the resistor is mounted outside the relay box the new fuse for circuit +30 gets very important as the +30 circuit is unfued inside the relay box. The wireing for the +30 circuit must be protected by the fuse in case there is a short circuit between the resistor and chassis.

Don't even think about doing these modifications unless you know what you are doing.
Don't blame me if you damage your cars electrical system.

Links

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