Outer Limits 4x4 Board

This afternoon I tried to start my troopy with no luck. Normally I hear a relay click and then another a few seconds later. I only hear the first relay now.

Any idea where the relays are located or any checks I can make?

86 Troopy.

Thanks. Daniel.

Ok I put the multi meter on the glow plug joining strip and turned the key on. No voltage. Bad connection where the strip joins on No.6 plug. Obv trying to get the nut off I broke the plug. New set of plugs ordered.