Thanks for the reply - will try to answer in order. Power only to Headlights absolutely nothing else. Headlight do not dim when ignition is activated. Fusible links are both good (think block 12, 52) Have not pulled ignition switch as it looked like a PIA to do. Will check white wire. Is there a resistance test for the engine relay and the xxx relay in the fuse box? How does the power loop from the battery through the starter on this engine.

Thanks again for diging in the bookwork!

86 Isuzu Trooper TD 5 speed
82 Isuzu Diesel I-Mark
86 300 SDL MB 126
85 300SD MB 126
82 300 D MB 123