howdy folks, i have a 1997 e300. 606 engine non-turbo. i suspect a bad glow plug relay, but want to confirm before dropping $130 on a new one.

symptoms: no gp light when turning key to position 2. engine cranks and cranks but never fires.

here's what i've done so far:

1. from the gp relay, tested voltage at the large gauge wire. got 12.83 volts.
2. from the gp relay, tested resistance on the 6 pin connector. exactly 0.7 ohms on all 6 pins between the connector and a ground point in the engine bay.
3. last year when i had the intake manifold off, i replaced the coolant temperature sensor at the back of the cylinder head. i heard the gp relay uses this sensor. so it's less than a year old, genuine mercedes part.

my question for the group is two fold:

1. from the gp relay, there is a two-wire connector, very small gauge wire, one white one brown. what does this do? does this go to that cylinder head temp sensor?
2. can i test the cylinder head temp sensor and associated wiring from this two-wire connector at the gp relay? if so, what is the test procedure? measure resistance across the two wires??

thanks for any ideas