996 Calibration: I'm not smart enough to read what PIWIS is telling me

[Keith Upson]

My 2001 C2 top has not worked the entire five years I've owned the car, full saga below.*

 

Without all the back story, here's where I am today. When I click "Calibrate," nothing happens and PIWIS 3 returns "Function inactive, end position not reached."

 

The front latch is reset per the service manual, and the clamshell potentiometer was installed at as close to 6.2k ohms as I can get it (about 6.24-6.26). [I rebuilt this engine in my dining room with my cat, 12,000 miles ago—I may not know what I'm doing, but I can follow directions.]

 

Top is in service position.

 

Actual Values / Input Signals

Latch locked  Catch not locked

Latched unlocked Catch not unlocked (can't be both, right, has to be one or the other?)

Convertible top Convertible top raised

Convertible top compartment Convertible top compartment lid unlocked

Right side flap up Right side flap not up

Right side flap down Right side flap down

Left side flap up Left Side flap not up

Left side flap down Left side flap down

Speed Speed >5 km/h (3 mph) (that's not correct)

Handbrake Applied

Latching hook Latch hook not actuated

Engine-compartment lid Engine-compartment lid closed

Convertible top button Close convertible top button actuated

Supply voltage 14.45 v

Warning light on 36044.3 min (!)

Actuation counter 1 1746

Actuation counter 2 65536

Calibration counter 2

Pot 1, convertible top 0.92 v

Pot 2 (conv. top compartment. lid) 2.51 v

Calibration: Pot 1 val 1 0.80 v

Calibration: Pot 1 val 2 1.27 v

Calibration: Pot 1 val 3 1.88 v

Calibration: Pot 1 val 4 2.29 v

Calibration: Pot 1 val 5 2.96 v

Calibration: Pot 1 val 6 3.22 v

Calibration: Pot 2 val 1 1.55 v

Calibration: Pot 2 val 2 1.82 v

Calibration: Pot 2 val 3 2.00

Calibration: Pot 2 val 4 2.71

 

These aren't even actual calibration values, are they, they're stored values from the last time it successfully calibrated.

It's my latch isn't it. There's a microswitch I've overlooked, a stupid simple on off switch, and because of that, it never starts the calibration process.  Guess I'm going out there one more time this weekend and taking that off again.

 

Insight invited, thanks for letting me ramble. 😄

Keith

 

*The Complete Saga

I bought the car like this in January of 2001. Tip cab with a top that had been manually put up via emergency procedure. Dash light for the top was on.

I found a matching hardtop an hour away that same week, manually put the top down, slapped the hardtop on, and drove it. Turns out, the left rear window regulator had failed and someone had manually pulled it up (the motor was missing) and then drove a drywall screw through the regulator frame close enough under the bottom of the window bracket that the window stayed up. I rebuilt both rear window regulators and in October of 2021, started working on the top. I probably didn't reset the latch correctly at that time, or the clamshell pot. Still, I told Durametric to calibrate and it started to. When the top moved doubt 1/2 way up, I could hear the pump motor straining and—since the rear interior panels were still off—I took a look: both hydraulic pistons were jetting fluid down the rain drains. I put the hard top back on. Then the engine failed, then (unrelated) I moved, and I spent all of 2023 rebuilding it.

July, 2024, I sent two cores to Cab Hydraulics in Sarasota to rebuild. Put them in, new hoses too, and this time I reset  the latch and the clamshell pot correctly. I think. But there was no longer a top warning light on on the cluster. I told Durametric to calibrate it, and it wouldn't. Opened a dialogue with the developers, sent them logs they asked for, did everything the guy said, and the last I heard was that maybe their software wouldn't calibrate it unless it was in an error state. Then (not their fault) I took a job and started the process of moving. Hard top went back on.

 

July 2026, time to get back to it. I knew I was going to have to have access to PIWIS, so I followed that thread on some other forum ("under $75") and got the image running on my shop computer. Which, I understand, isn't the same as pulling up to the dealer, so I'm aware that's a possible failure point. I 100% believe the latch and clamshell pot to be correctly reset now. No dash light. When I click "Calibrate," nothing happens and PIWIS 3 returns "Function inactive, end position not reached."