1977 main harness

[drophit]

Does anyone know if the 1977 911s main wire harness will work in the 1975 911s?

[Jim Sims]

I assume this is related to your previous post regarding problems with license plate lights and right rear tail lights in a 1975. Pulling and replacing the main wiring harness is not a task to be considered lightly. It may be nearly impossible to do without taking the car extensively apart - it runs through the center tunnel between the seats. The main wiring harness also contains most of the wiring under the dash! There are differences between 1975 and 1977 harnesses that reflect changing features in the cars (such has the change from mechanical speedometer to electronic speedometer); the wiring harness part numbers are keyed to the engine serial numbers. It is likely a 1977 harness could be made to work in a 1975 with minor modification.

To your actual problem: there are separate wiring harness sections (with connectors) that feed the left and right rear lights (including the license plate lights); they are the same for years 1975-1977 and have the Porsche Part no.: 911.612.039.03 - they will be expensive if they are available.

Unless there is good evidence that the rear portion of the main wiring harness and the taillight wiring harnesses are bad (and they do get cooked by the heat of the engine) I would look elsewhere for your problem. Incorrectly wired light switch at dash or incorrectly wired rear tail lights, wire insulation cut where it crosses a sheet metal edge, incorrect bulbs (note some of the bulbs have two contacts on the base bottom) or a short elsewhere in other circuits fed by the fuse(s).

Cheers, Jim

[drophit]

Yes. Well heres the full story first license plate lights went and the fuse just blows. Now the right side front and rear lights are gone, is it possible this could be the head light switch itself? We have already replaced the harnes section that goes form the body to the actual tail lights. Still fuse just blows.

[Jim Sims]

The common element in these failures (they are on separate fuses) is the branch of the main wiring harness running to the right along the front of the engine compartment and then rearward along the passenger side or the right rear taillight wiring harness. You appeared to have removed and installed engines. Check to see if you have pinched and cut the insulation in these two sections of wiring harness. I will conjecture it is the branch of the main wiring harness that was damaged.

[drophit]

hum ok will look there, thx