Tony, the wiring for the fridge relay is a little tricky because of the
way VW chose to do it. The blue wire supplies 12 volts to trigger the
relay whenever the alternator is charging. The other wire (red/black
according to Bentley) supplies a path to ground for that 12 volts and
allows the relay to trigger. That ground path is indirect.

Since you did not describe how you had the test light hooked up I must
assume. I assume you had one lead of the test light touching ground and
then probed the relay terminals with the other lead. If so, what you
have discovered is that the indirect ground path is not sufficient to
allow the relay to trigger. I can think of a couple of reasons why this
might be but the easy solution might be to use a direct ground instead.

Mark

Tony Thompson wrote:
>
> I don't have a solution but a related question. I have been troubleshooting
> the fridge relay under the seat and adding a second relay to handle
> auxiliary battery charging. The blue wire is supplying charge voltage to the
> relay but it will not switch over unless I put a test light on the terminal
> for the red and white wire which is the other end of the relay trigger
> circuit. As soon as I touch that terminal the test light lights, the relay
> closes and supplies power to the fridge and the other relay trips and starts
> charging the battery. I have checked and rechecked and replaced the relay's
> as well as going back to the single relay configuration without luck. Any
> ideas short af permanently wiring a test light??
> Tony
>
> 85 Westfailure