S4 dash loom: make or buy?

[JohnCh]

After confirming my slow windows are due to a weak ground coming through the switches, then poking my head under the dash to investigate the rat's nest of wires and view some questionable connections, I'm coming to the conclusion, that a preemptive dash rewire might be the right thing to do. I'm fine making functional improvements during that process — I'm not a stickler for authenticity in areas that can't be seen provided those changes are improvements — but I'm not certain I want to roll my own from scratch and am considering starting with the Autospark dash loom. I've read mixed things about their harnesses, particularly if someone is expecting a plug-and-play solution.

If my goals are to remain faithful to the wire colors present in schematics, and want to introduce changes like relays for the windows, modern LED compatible relay for the flashers, Deutsch connectors to make future removal easier and potentially some other tweaks, is the Autospark a good starting point, or am I better off building something from scratch? The car is a Federal '68 S4 FHC.

I'm not a complete stranger to custom dash harnesses, having recently built a sub loom for my Caterham to integrate a custom dash setup, but to be fair, that was relegated to the switches, gauges, warning lights, and immobilizer. I didn't have to create a loom from scratch, just significantly modify and add on to what came with the car. On the one hand I love a challenge and learning something new, but on the other, I'm inherently lazy and like instant gratification Advice welcome.

Thanks,
John

[The Veg]

A few years ago when I had my Plus 2's dashboard out I addressed some of these issues. I found that while the dash-harness was in generally good condition, I did put new terminals on all the wires as the original ones seemed quite oxidised. A lot of the bullet-connectors were so stuck from oxidation or corrosion or something that they could not be separated. I replaced them a ll with a pair of 15-pin Molex plugs to make future removals and installs easier. One plug was full and the other used all but 3 or 4 pins. The two plugs were oriented in opposite directions to make cross-connection impossible.

As for the window earths, I ran new heavy-gauge earths straight from the motors to the chassis-bolts on the tunnel and that made the windows move with authority after all other fixes failed to make a difference.

[JohnCh]

Thanks. In addition to corrosion on the terminals, I'm concerned that after 56 years, the insulation is reaching terminal brittleness.

Interesting about the +2 windows. It sounds like they operate differently than the Elan which has two wires to the motor plus a ground to the body for radio noise suppression. The switch flips which wire receives positive and which receives ground to control motor direction, so a dedicated ground to the motor won't work. I need to address a solid ground at the switches, which appears to require dash removal, And as long as I'm in there....

[The Veg]

Thanks. In addition to corrosion on the terminals, I'm concerned that after 56 years, the insulation is reaching terminal brittleness.

Interesting about the +2 windows. It sounds like they operate differently than the Elan which has two wires to the motor plus a ground to the body for radio noise suppression. The switch flips which wire receives positive and which receives ground to control motor direction, so a dedicated ground to the motor won't work. I need to address a solid ground at the switches, which appears to require dash removal, And as long as I'm in there....

Good point, I'd forgotten that the Plus 2 does use different bits including a GM motor- same one you'd find in a '70 Chevelle, believe it or not- and yeah, dedicated earth through the motor's chassis (in the Lotus, earth-wire to one of the mounting bolts) and the switch sends the +12V through either of the two wires that connect to it.

But the point remains, both the + and the - need a good free-flowing connection for the motor to work strongly. Even putting relays for direct battery-power on the +12 wiring didn't make a difference with mine until the earths were improved. So I guess if your window-earths have to go through the switch, then from that point run them as directly as possible to the chassis.

[Andy8421]

John,

As soon as you go down the non-standard route, the argument for starting with a standard loom becomes weaker - particularly if you aren't concerned about wiring colours and want to change connectors.

If standard colours do matter, then using a standard loom as a starting point avoids having to buy short lengths of wire in specific thicknesses and colour combinations that may prove difficult to source.

Andy.

[StressCraxx]

I vote to buy, then modify/add relays to suit your purposes. It will be easier for the next owner.

One caveat. I obtained a complete new harness during the rebuild of my S3 Elan. As I started going through the connectors for the tail lights, I discovered two wires in the harness had pulled out from the bullet connectors. I also looked at the wires coming from the tail lights. The bullet connectors at the tail lights were crimped at the bare wires and also crimped at the insulation end as well. I looked over the entire harness and discovered NONE of the bullet connectors were crimped on the insulation! So before I can install the new harness I need to finish crimping the connectors on the wire insulation.