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OBC MOd on 03 Boxster

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G/Day forum,

Would appreciate some help and noticed some real experts on here. Live in Australia and I have just fitted the 4 stalk lever to my 2003 Boxster as I wanted the OBC option (M659) . It had the Cruise option that worked fine (explain later). After fitting and wiring as per many good intructions on this forum, except founf that with second hand 4 stalk from a dismantler, didnt need to remove sterring wheel and just stalk covers and dash. Anyway went to my dealer who is most helpfull, Service manager is a Porsche freak and racing drive, they enabled my car but the OBC wont work. I have since discovered that the 03 on Boxster diagram (dealer gave me a copy) shows a sixth wire to the C plug (grey to instrument panel) pin 25 on panel called Lever Inside. Most hack descriptions show 5 wires (a Earth and 4 wires to plug) and the Bently manual for the 01 model shows 5 wires and a this is what I used to wire it up, which lines up with this forum's instructions for late models.

So I'm going to have a look tonight and checked pins to the dealer 03 diagram. The 03 Diagram shows:

OBC Lever Pin - Instrument Plug C

A1 - Earth on GP 17/B6 (below Inst. Panel)

A2 - C23

A3 - C22

A4 - C21

A5 - C24

A6 - C25 (this is the one I have not seen before in any advice and says its "Lever Inside")

My questions are Does the 03 on model have an extra swith in the lever that is required, didnt notice a 6th wire ?

Is the 03 model C instrument plug wired same as 01 models.?

Now my Cruise doesnt work and somehow think CAN system may be issue due to wirng wrong?

I may be able to answer some questions myself and I will post anything I find out as I have never read anything about this differenec in 03 to 02 OBC.

By way if anyone needs any adive on the alternative way not requiring wheel off for OBC mod please yell out. Have also found easier way to wire the 03 (optical amp) rear speaker mods by going thru bulkhead also.

Thanks for this forum as greta help to guys like me that are down under.


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I have done the retrofit on two 2003s. 4 wires to the instrument cluster connector and the 5th wire to ground is how it was done. Just looked at a 2003 wiring diagram and you are correct. It shows a 5th wire for the OBC in position C25 called "lever inside." We never put a wire in this slot. My guess is that there is a wire in this slot if you have the OBC as a factory option. Keep in mind that you are doing a retrofit to mimic the OBC option, but what you actually get is what the OBC option looks like on a 2001. A 2001 wiring diagram does not show a wire in slot C25.

A 2003 instrument cluster with the OBC as a factory option has a dot matrix middle display. Your non OBC instrument cluster does not have a dot matrix middle display. When you do the retrofit on a 2003 you do not see all the information you can see if the car had the OBC from the factory. Instead, you see the basic displays used on a 2001 with the OBC option.

Your OBC may not have been turned on. Unless you have a very early 2003 the order type need to be entered before you can turn on the OBC. If it has in fact been turned on then you may not have it wired correctly from the connector to the stalk to the instrument cluster connector, plus the ground wire. The stalk could be bad.

No clue on why the cruise control does not work. Make sure the connector to that stalk is still connected. Maybe the guy turned it off while he was trying to figure out how to turn on the OBC.

Lastly, make sure all 3 connectors on the back of the instrument clusted are seated properly and locked down.

Hard to figure out what is going on over the internet and not having the car in front of me.

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G'day Mate,

I did the OBC hack on my MY03 base Boxster last year. These are the wire connections I used:

1. OBC Pin #1 - to ground (earth),

2. OBC Pin #2 - to grey connector position #23,

3. OBC Pin #3 - to grey connector position #22,

4. OBC Pin #4 - to grey connector position #21,

5. OBC Pin #5 - to grey connector position #24,

which are the same as you have indicated you used. So far, so good.

The wiring diagram in my Bentley service manual, pages EWD-64/65, shows a sixth pin on the OBC plug; but it is not hooked up to anything. Likewise, the wiring diagram shows a position, C25, on the grey plug; but it isn't hooked up to anything either. So that shouldn't be a problem. By the way, I installed a Carrera instrument cluster in my car earlier this year and the "improved" dot matrix display works just fine with the above connections.

I did have a bit of a bother getting the OBC "turned on". My dealer tried several times after insuring the type order code was properly entered. The technician finally ran the "sports car hand over" routine and, viola, the OBC turned on. His fingers were flying on the PIWIS so it is our best guess that the sports car turn over routine was, in the end, trump. Toolpants and Loren have been very helpful in outlining the PST2 / PIWIS procedures in several OBC threads. Check the archives for OBC.

The cruise control problem....if it worked before you did the OBC hack and it doesn't now....may have been caused by you partially disconnecting one of the cruise control wires from the connector or the connector itself from the stalk. In any event, the PIWIS can probably pinpoint the problem.



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