Ken Wilford has a good video on youtube about trouble shooting and
repairing this. Here's the link:

https://youtu.be/KcIL_K9H8zQ

John
On Jul 7, 2016 21:42, "Ryan Shawley" <easywind1975@hotmail.com> wrote:

SO I recently purchased a 91 automatic and sold my old faithful 86 westy.
Been running down some bugs, doing the fuel line change, etc.

The factory cruise control currently does not operate.  I tried the easy
fix of the vacuum brake cutoff switch replacement but that didn't help.
Vacuum solenoid appears to hold vacuum and the line running to front also
seems to hold vacuum.  I began the Bentley troubleshooting procedure by
disconnecting the cruise computer and testing at the computer connector.
The stalk switch checks out fine and the speed sensor appears OK.  When I
do the brake switch test it indicates test light should be on until brake
pedal is depressed and then it should go out.
Well the test light does not come on at all (ignition switch is on, gear
selector in D) when connected to terminal 3 on the connector.  So I've been
trying to track down what the hell is going on, I traced the wires to the
relay and brake light switches.  The brake light switches appear to work
correctly.  One of the wires to the relay is the wrong color but appears to
go to correct terminal.
I am not very good with electrical stuff so I need some help here....
I do not appear to have continuity from the Bk/R wire from the relay to
cruise computer connector.  Should I?  Secondly the blue wire going to the
relay (which should be BK/Y) appears to work somehow in conjunction with
the D+ alternator wire, with ignition on I get faint light on test light
and a voltage of about 1.3 volts.  Same reading at the alternator with key
on and d+ connections cleaned up.  In my mind I should be getting like
close to 12 volts back there.  Is this a red herring or am I on to
something.
Here's a link to wiring for 91 auto with cruise.
http://images.thesamba.com/vw/gallery/pix/1528225.jpg
Ryan in Johnstown