Boxster Project: Convertible Top Switch Hack
Simple, free, and fast...the hat-trick of DIYs :-)
Carolyn: “Why is the Boxster hard-top in the office?”
Wan: “Because the relay hack worked!”
Carolyn: “And I’m sure that is very good news indeed, but why is the Boxster hard-top in the office?”
Either a very weird car crash, or… never mind, we’re not even going to tell you.
Backstory
The 22-year old Boxster’s soft-top would not go up. Because it was getting close to winter, we decided that we would just put the hard-top on and not worry about the soft-top until the Spring. Problem sorted (for a few months).
We didn’t really want to put the hard-top on, though, because the forecast for the next week indicated unseasonably warm temperatures, and we wanted to take advantage of that.
So, we got off our butts and hacked a fix for the soft-top issue.
After 22 years, this car is still a thing of beauty.
We had this amazing realization pop into our heads that the handbrake indicator on the dash was NOT ON when we engaged the hand-brake. This Porsche safety precaution normally keeps the convertible top motor from activating if the handbrake is not also engaged, and prevents drivers from putting the top up/down while driving (some people…)
The handbrake IS engaged…really!
The handbrake on/no dash light combo suggested that the likely soft-top-won’t-go-up issue was that the handbrake’s micro switch—which tells the system that the handbrake was engaged—was not working.
In other words, the handbrake was working, but the thing that told the rest of the car that the handbrake was working was not working.
As this was not an actual mechanical problem, it could be a fairly simple DIY fix. So we went for it.
Possible solutions
- Bypass the handbrake switch, so that the system thinks the handbrake is ALWAYS engaged.
- This should work, but it’s not the best option, because the dash light then would ALWAYS be on, handbrake engaged or not.
- Also, this would require some disassembly.
- Fake out the convertible top’s relay that detects whether or not the handbrake is set.
- A better approach, as it requires very little work and does not need anything to be taken apart.
- Also, this would be a relatively quick fix.
What we did
As we really wanted to have the top down until the weather says we absolutely cannot, we went with the “hack the relay” option.
Of course, it worked. 🙂
Convertible Top Switch Hack
The Relay
The system in our 2000 986 Boxster relies on three pieces working together for the convertible top to work:
- A relay controls the activation of the motors for moving the convertible top. The relay relies on info from:
- the soft-top lock, to tell the car that the top is secure, and
- the handbrake, to tell the car that it is NOT moving and that the handbrake is in the “engaged” state.
In US cars, the relay is located in the underside of the dash on the driver side. To find it, we had to contort ourselves and look up. In the photo below, it is the rectangular white block with the black square on the otherwise blank label (from this angle). Note: the relay will fit if rotated, but you shouldn’t rotate it because it won’t relay anything if in a rotated state.
A doo-hickie, a doofer-dangle, and a whatzit. Got it.
The text on the relay label gives a brief indication of the functions the relay controls:
- Pin #15 detects whether the hand brake is set;
- Pin #18 detects whether the car is moving.
Of course, both pins rely on sensor info from other parts of the system, hence it can be, as they say, “fooled.”
Always check all sides of a whatzit if the first side is blank.
The Pins
Next to each pin is an embossed number. We took care and made sure we worked with the proper pins, as the layout is symmetrical and eyeballing it would have been a bad idea.
The embossed numbering is much easier to see in person.
Bending Pin#18 and grounding Pin#15 ought to, theoretically, make the system think that:
We used a connector for the grounding wire to make it easier to run the wire to a metal ground point and then connect it to the relay.
Quite simple, actually.
The Fix
After bending the pins and attaching the ground wire, the relay was ready to go back into the Boxster.
The last step was to find a grounding point on the car. Any metal part of the car will work for grounding. We found one and ran the wire to the relay.
Screws: always useful!
Using a connector is not required as running a wire straight from Pin15 to wherever would absolutely be fine…and less work. However, doing it our way will make the relay easier to take out should we ever had to.
Obviously the wires have not been connected up in this pic.
As luck would have it, the space between the relays was just wide enough to tuck in the connectors. Slipping the connectors between them kept everything neatly out of the way.
All cozy – and working.
The Test
With the relay replaced, the only thing left was to test whether the top would now go back up, even if the handbrake was not engaged.
When we pressed the raise/lower button on the dash…the motor came to life. Success!
Hand brake not engaged, top operational. Hack successful!!!
As for why there is a hardtop in the office…we knew that top-down weather would not be around for much longer. Since we had already brought the hard-top up from storage, we didn’t want to go down and up the stairs with it again. It’s only a week, two at the most…come on 🙂
No, we are not picking sides. Yes, we love you both.
FinalThoughts:
This DIY is very simple and fixes a common convertible top issue. It required very simple tools (wire stripper, small pliers, a wire) and can be done in less than 10 minutes…IF the problem is due to the micro-switch of the handbrake.
BTW, this DIY is partially covered in Project #72 in the book 101 Projects For Your Porsche Boxster.
Links to items mentioned:
Hi Wan, the root cause of the problem is probably the switch below the handbrake handle which senses if the handbrake is engaged or not. I’d guess that that switch broke off or slipped out of position or something. Checking this would require disassembling the rear middle console, I guess. Greetings, Ludger