Diesel guru needed - 606.910 GP relay issue!

[WINGAS]

We recently picked up a pretty cherry 1995. 232K on the clock. This Sunday I replaced the wiring harness as it was still oem and deteriorating. This because the GP system began exhibiting issues, ie. the glow indicator would come on for a minute after starting , indicating a fault. And then it simply failed. No GP indicator, no preglow. So, I reckon lets get a proper harness in there first before the relay.

The only ? I had during preglow harness install was the 4-pin temp sensor which didnt seem to have an orientation. ??? which may be the issue now....

With new harness on , my son ran the car w/o GP system ( which I pucker on badly) and when the new relay arrived, I unpuckered - not ...so ...fast.....

With the new relay in, the car will not start. Plenty of CCA, spins that 22:1 compression motor quickly, but it simply wont fire.

Disconnected the 5 pin connector on the relay, GP indicator doesn't come on, yet same condition. Turns well - but no start. Check fuel - proper.

Put old relay back in, and it fires to live. Unhappily w/o preglow, but fires.

Suppose a bad relay, but what else could be going on? It is my "?" during preglow harness install on the orientation of that 4 pin temp sensor?

Thank you for any thoughts..... I am stumped..... please help!