Headlight Rewiring

A Zimmer Golden Spirit is for most owners a pretty old car, lasting between approx. 50 and 30 years. Only the very rich among us can afford to have a new Zimmer build for them.

And old cars suffer from : ... bad wiring !

(This is a Zimmer mod.)

Our #620 sufferd great at the headlight section. One day we would have 2 dim lights, the other day we would have only one high beam. Or worse, no Dim but 2 High beam. Also the fog lights would or would not come up, not to speak of the city lights that might run on 1/25th of power on the right side and full on the left... .  So first I started to completely rewire the Dim/High beam for the H4 bulbs.   

While diagnosing the problems, I noticed that all H4 wiring was running through the steering column, apparently, as there were no relays in the Mustang Service manual electrical diagrams.

So I started designing a safe , fused and relayed circuit. 

I used 2 relays, 

Rel#1 gets its trigger from the main lights switch, if pulled in the 2nd position. 

Rel#1 will switch the main (fused) 12V to relay#2.

If relay#2 is not triggered, it will route the 12V default to the new harness of DIM. If the High Beam is switched (on the steering column handle), it will trigger relay#2 to switch the 12V to the High beam harness and vv.

Connecting Rel#1 and Rel#2

Soldering station in the dining room :-)

Relays mounted to inner engine room.

Also, (above) I mounted a new multi ground terminal and grounded it with 2 wires to the chassis. 

Next, I had to route the new wires from the steering column to the Headlight nacelles. Beware, this is a cumbersome route. From within the nacelle down, back up into the engine compartment, through the firewall up to the steering column. Also, I routed a separate fused 12v lead direct from the battery in the trunk al the way to the relays in the engine room.

3-wire harness (Ground, Dim & High beam)

I replaced all wires, including the connector block for H4

Next I needed to find 2 trigger wires in the Steering column. (Try on Error). I could not get the main lights switch out, due to short harness, so I diverted my goal to the steering column levers. The first trigger is needed to switch on the Dim and the second to switch on the High. Both are in the right section of the left (green) connector. Beware: The High beam lead is low on High beam and high on Dim beam. So the relay#2 needs to correspond to that when  the 12V lead has to be switched between them.

If you make no mistakes, and if you fuse the main 12V lead, there should be no problem.

But only change wiring on your own risk :-)