Ok. So I dove in and yanked the engine portion of wiring harness.

It seems that even though this harness might qualify as being old
enough, it seems I indeed got the wiring in question, correct. Image:

https://lh6.googleusercontent.com/-lESJLRAe8CU/UwgdNcmAyQI/AAAAAAAAI10/vY0vxi0J8-k/s720/Jetta%2520Hall-TPS%25205%2520Volt%2520Wire.jpg

This harness required many repairs. (new wire shunted in) one being
the black/yellow wire from the 28a plug to the hall and TPS plugs. The
blue/red wire from G3 (+ junction in the harness) to fuel injectors
was uncut (save for yet another repair I made while the part was out),
so it appears that the hall indeed takes only 5 Volts as supplied by
the ECU.

Neil.

On 2/21/14, Neil N <musomuso@gmail.com> wrote:
> Hi all.
>
> This is for Motronic on my 2.0 Jetta powered Vanagon. I am chasing
> down a consistent hot start issue. (fuel pressure is ok) I doubt the
> hall on distributor is the issue but I am curious of the wiring to it.
> I had to repair and modify the wiring harness for this engine swap.
>
> Bentley shows a difference in the + reference wiring to the hall. Most
> model years receive ECU supplied +  (5 Volts?), others receive battery
> voltage. My Jetta Bentley specifies a minimum 4 Volts at distributor
> hall connector.
>
> I can supply images of the diagrams if needed.
>
> I will re-measure this, but would connecting the hall to 12 Volts
> shorten the life of the hall, or would it cause the hall to send too
> high a voltage square wave to the ECU? If so, is this damaging the
> ECU?
>
>
> Thanks,
>
> Neil.
>
> --
> Neil n
>
> Blog: tubaneil.blogspot.ca
>
> '88 Westy http://tinyurl.com/c8rlw6p
>
> '81 VanaJetta 2.0 "Jaco"  http://tubaneil.googlepages.com/
>
> Vanagon VAG *Gas* inline-VR Engine Swap Group:
>
> http://tinyurl.com/d7gd5ej
>

--
Neil n

Blog: tubaneil.blogspot.ca

'88 Westy http://tinyurl.com/c8rlw6p

'81 VanaJetta 2.0 "Jaco"  http://tubaneil.googlepages.com/

Vanagon VAG *Gas* inline-VR Engine Swap Group:

http://tinyurl.com/d7gd5ej