electrical mess behind dash.Urgent help needed

[7783911]

The PO did some kind of franken work to adapt 83 sc engine to a 77 Targa

so as I go to install refurbished gauges last night..disaster. Lost all power to gauges (not lights)

So as i know, lighting is from the light switch direct. But the other power supply to gauges comes off the harness extension behind the speedo and it looks like toast (fraye..like it git chewed on or worse.

Timmy (i hope your on today) or anyone..

where does that red/black stripe originate from in the harness..is it a branch or is it from the fuse box..if so..i can run a direct replacement from a power source (which I assume needs to be a keyed circuit) since I can not get into that loom to trace the wire and do a direct replacement for wherever is fried (continuity is gone even before chewed area

second..the oil temp/pressure gauge is a mess of wires..i think they tapped additional grounds from a common post (# 6 in picture (red dot)) can someone tell me what should be where on this photo. so need to confirm 4,5,6,7 and 9




Lastly (i hope) for the speedo...which of the 4 posts should power run to? from there i assume based on circuit diagrams that it then bridges to the other instruments?..assume post 1 is far left as you look at the back of the speedo.

Which should have power supply from loom?

HELP

pictures appreciated since my ability to read Porsche wiring diagrams just isn't there

77 targa wiring back of gauges pictures
83 gauge wiring in case adjustments were made to accommodate the new engine

i ve searched pictures/thread but no luck so far

[Dpmulvan]

Number 6 on your temp oil is red/ black, 5 is green/red, 4 is green/black bulb sockets are blue/black
If 9 is below and between 5 and 6 that should be green/brown. 7 should be two grounds brown.
Hope this helps

[Dpmulvan]

Speedo looking at back from left to right 1 st connection 4 brown grounds, 2 connection brown and brown/black, 3 connection white/ red, And last a red/blue and red/black. Bulbs blue/black and white/ green.

[7783911]

thanks!

I will redo the feed to speedo and create new jumpers to other gauges one timmy2 instructs me on best method to replace crappy power feed

[timmy2]

Just fixed the same issue in a dash harness last week.
Likely the wire melted all the way to the 6 pin connector for the ignition switch.
See picture below of what I found.
I spliced in a new wire as close as I could get to the connector, with good insulation and built a new “gauge power” harness for it.
(I used a non insulated splice with adhesive lined heat shrink, not that crappy type that is in the photo installed by someone else.)

[7783911]

Thanks Dennis, I pm d you re the new gauge harness, i will look into the source wire from the ignition swicth and see if i can get started today

[timmy2]

Once repaired and tested it looked like this for the gauge power wiring section (ty wrapped as a bundle)

[7783911]

beautiful..but is it all needed for what I am trying to do..i am open to advice since your the guru. This shows alot of plug junctures etc and i dont think i could use without tearing dash apart?. I was thinking just the part from the switch to a new harness that spans the gauges with power feeds and leave the rest as is? Or is this new harness all inclusive and replaces every connection to the gauges?

[timmy2]

Originally Posted by 7783911

Thanks Dennis, I pm d you re the new gauge harness, i will look into the source wire from the ignition swicth and see if i can get started today

I replied to your PM with my cell number.
Give me a call and I’ll walk you through it.

[7783911]

will do, thanks

[timmy2]

The gauge power section of the harness is all daisy chained together. It runs from the female ignition plug through the harness to the gauges.

[7783911]

so its just a portion of what your showing?

[timmy2]

Originally Posted by 7783911

so its just a portion of what your showing?

Runs from visible area through harness to the female 6 pin connector with the yellow wire sticking out on the right. (On my phone anyways...)

[7783911]

PM sent

thanks everyone..now to go rebuild the entire frunk ventilation system which i removed to try to fix the wire but it was toasted. I think I will run a fused switched new wire, tie onto old loom, rewrap , re install the socket and build a new series of power from tach to other gauges. Guess I know what i m doing this weekend