|TPS wiring diagram|
The multi-meter has been sitting on the top of my toolbox from day one. In retrospect, it is probably the most used tool I have. My 13mm ratcheting wrench is probably second. Anyway, on to its use with the wiring troubles...
|old TPS plug|
If the wiring was good, and the bad grounds weren't part of the problem, then the issue must be at the potentiometer (that big variable resistor the wires go to that sends the how-fast-to-go signal in the drive-by-wire set up). This is often referred to as the "Throttle Position Sensor" or TPS. I unplugged the TPS from the wire bundle and disconnected it from the under-floor of the bus. At first, I thought the TPS got wet from the trip to Bend and it would work after it dried out. I read some threads about that happening for folks. On closer inspection, I could see that as the wires left the TPS, the insulation had stripped away. I could see copper. Since the TPS was pressed against the metal underside of the bus, the signals were shorting out right there.
|bad TPS wiring|
The 1998 New Beetle donor from which I got the engine and related components had an accelerator pedal / TPS that was unique. By 1999, the components had changed, and the wire plug had as well. Gone was the old 2x3 (2 rows of 3 pins) round-ish plug. In its place is a 1x6 flat plug. Neat. The old TPS could still be found on the interweb, but NOS and even used on eBay were going for upwards of $400. Snort-giggle. Yeah, like I'm paying that. The new pedal assembly is available online for just over $100 or almost $200 for a genuine VW part. Considering the failed promise, I got the genuine VW part. The new pedal has the TPS integrated into it. You can't just remove the TPS and use it like I had before. This meant that the first real change to the cabin was necessary: the old pedal would go away and a new model pedal would have to be retrofitted. *pausing for the purists' gasps of shock*
Wire Plug Wire Plug
Suspend a Pedal
With the wiring in place, I plugged in the new TPS / pedal assembly and
I think, as I look back on this build, I'll remember this moment. I did so many little things to make it better, faster. In the end, the second generation pedal and assembly allowed me to tap into the horsepower and torque I originally envisioned when I started this project. I can't wait for our next festival. Now that I've fulfilled my promise to Hapy, I don't think he can wait either.
That's it for today. As always, thanks for following along.