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.

[RichardHawkins]

John,

I was horrified by the old wiring on 1968 S4 fixed head, and decided to do my own thing. I think bullet connectors are awful. My approach was a bit different, I decided on a donor car that had the distribution board by the passengers knees, in my case a Skoda Felicia (part of the VW group). This vehicle has 8relays and 22 fuses, and at the time 10 year old cars were scrap value. I carefully dismantled the Felicia removing and labelling all the wires, I found a Haynes Manual very useful for the wiring diagrams. I sold the old Felicia to the scrap man who came and collected it.

The Felicia provided enough wire and connectors to nearly do the job. I have used some Deutsch connectors in the front of the car as I didn’t have enough of the connectors used in the Felicia and could not find a supplier until after I had finished!

My electrical knowledge is rudimentary, so using a donor car solved problems such as relay types and wire sizes. I made a serious error, I routed the wires when the heater was not installed, and then found the heater clashed with most of the wires behind the dash. I then had to buy new wire as the Felicia did not provide enough to correct my error, this error also took a long time to correct, as the wiring had been complete.

The work took about a year and correcting my error probably another 6months. I do have a much better system using better connectors and gained a perverse satisfaction from the achievement.

Was it worth doing? I am not sure, with the knowledge I now have if I had to start again I think I would still do it and hopefully much quicker.

Hope this helps,

Richard Hawkins

[JohnCh]

Thanks everyone for the responses. I spent a lot of time in the garage today reading through old posts on this topic and digging a little more into the car. The first discovery is that my headlights no longer pop up. I checked them when I bought the car six years ago but haven't tried them since. My second discovery is that the headlights work just fine with the pods closed. From what I've read, they shouldn't. Between that and looking at the wiring in the nose, realized it's not just the dash loom that needs attention. I think I may be on the brink of scope creep.

StressCraxx, I assume that's the Autospark harness? Where did you buy it? I suppose if I am modifying it, then those type of quality control issues aren't as big a deal, but it still doesn't instill confidence.

Richard, I'm not sure I want to go that far down the modification path, but I do like the idea of modern car conveniences like more than two fuses for the entire electrical system.

[Andy8421]

John,

The wiring on the Elan was poor when it came out of the factory. Based on standard Lucas practice of the time, apparently little thought was given to the implications of a lack of earth return through the body, and the flammability of the car.

If your wiring is original, I would strongly recommend replacing it all. In particular, the combination of heat and water in the engine bay and nosecone mean the insulation on the wire will have gone hard and cracked, the wire itself will be corroded and connectors (which were never water resistant) rusted and failing. Enthusiastic DIY owners often hack the wiring around, and what is left after all this will give you years of trouble chasing elusive earthing problems up and down the car.

The headlamps were designed to switch on when raised if the headlamp switch was in the on position, or flash if raised when the switch was set to off. Two repurposed interior light door switches are fitted to the headlights to detect the movement. These cheap and nasty switches (optimistically called 'microswitches' in the manual) were originally designed to be protected by fitting in the door pillar of a car. In their Lotus application they are open to the elements, get wet, and fail. Many owners fed up with unreliable headlights disable this aspect of the wiring so that the headlamps always come on with the headlamp switch irrespective of headlamp position. It is likely that this has been done to your car.

Good luck.