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How to use PIWIS Tester 3 to enable High Beam Assist for Porsche 991

Car model and year: Porsche 991

Purpose: to enable High Beam Assist

Which device:

Definitely,  piwis tester iii for porsche



How does this work? I know what it’s suppose to do, but do I have to turn it on, or does it go into high beam assist automatically?

I can make it go into HBA and I can see the little dash icon illuminate ( the headlight with an “A”). Is this the only way?


Just making an assumption here, but if you leave the high-beam stalk in “low” position, the headlights will stay “dipped”; if you move it into “high” position, the auto function then takes over.

EDIT: Reading the manual it states “The function activates in darkness if the following conditions are present:
-Light switch position AUTO is selected.
-Vehicle speed is more then approx 37 mph (60 km/h).
-High Beam Assistant is activated on the multi-function display in the instrument panel.
-High Beam Assistant on is selected on the high beam stalk.

High beam assist is not available at speeds less then 20 mph (30km/h).”

Pg 120:
Activating High Beam Assist:
1. Main menu: select “Vehicle”
>”Light & Visibility”
>”Exterior Lights”
2. Select “Hi. beam assist.”
3. Confirm your selection.

Apparently Activated or Deactivated remains selected when you turn off the car, i.e. you should not have to reset it each time you climb aboard..


once initiated, it remains functional to speeds as low as 30 km/h (18.7 mph).
I believe the factory thinking is you are supposed to be out of the city/town for it to work, so must exceed 60 km/h to initiate the functionality (the system assumes you are out of town if you are going 60 km/h=37 mph, as EU drivers “tend” to be kind of fastidious about speeds in town).
So you should be fine on your rural country road, as long as you don’t have to *****-foot around the bends!

Enable Porsche 991 High Beam Assist using PIWIS Tester III 1
Enable Porsche 991 High Beam Assist using PIWIS Tester III 2
Enable Porsche 991 High Beam Assist using PIWIS Tester III 3
Enable Porsche 991 High Beam Assist using PIWIS Tester III



Most people seem say the standard headlights are bixenon 25W. However with the “Bi-Xenon Headlights in Black incl. Porsche Dynamic Light System (PDLS)” ($690) option they are 35W. Does anyone have any proof that the two are different?



In Europe, any headlights putting out a certain number of lumens require both headlight levelling and a washing system. The standard (non-PDLS) lights lack the headlight washing nipples, so I suppose that’s evidence the light output is inferior.


the bulb for non-PDLS cars is 25W and the bulb for PDLS is 35W, and the above-mentioned reason is why PDLS includes headlamp washers. I can’t imagine why the GT4 would be any different from the other Porsche models in this case in bulb specs. Fwiw, the German GT4 catalog PDF specifically says that PDLS includes 35W bulbs on Page 23, although it doesn’t say that the standard is 25W.



It is stated in the catalogue that the regular system has 25W and the PDLS has 35W. What happens if you just upgrade the bulbs from 25W to 35W in the regular system?

I was wondering that myself, but I haven’t seen anybody talk about doing that. I suppose it’s possible the connector is a different size that physically prevents it, but even if it’s not, if the circuitry for the headlamp is also different when PDLS is optioned, then putting a higher-wattage bulb into a socket that isn’t designed to support it might shorten the life of the bulb and/or burn out the circuitry.



That is true for 12V systems to an extent. Keep in mind that in Xenons you have a ballast that steps up the voltage tremendously. I’d be more worried about the supply lines, connections to or the ballast itself than the bulb. The other thing could be a sensor that can be controlled, adjusted via PIWIS III, thereby throwing a code.