Plus 2 Harness Query

[111Robin]

I ordered a harness from Autosparks for a Plus 2 with alternator conversion added as my car already has one. Car is late 68 build. However having laid out the harness in the engine bay it still has the wires next to the wiper motor for connecting to a two fuse holder. My car has a rail of fuses above the passenger footwell along with the bank of relays as shown. I have no way of knowing if these are original to the car although they do look to be not home made at least. Is this just another variation on the possible wiring arrangement ?. I have the workshop manual showing the different diagrams so just trying to get everything in order before I start trying to make the new harness work.

[111Robin]

Anyone able to confirm a possible date for this type of relay and fuse arrangement ?. It looks to me as if it could have been rewired when the chassis was replaced as this arrangement doesn't tie in with the wiring diagrams. A lot of the wire colours are also different from the diagram also. Trying to mate the new engine bay harness with this is proving quite difficult. There are two multi pin connectors between engine bay and harness, 9 pin and 20 pin.

[ncm]

As I think you already suspect, the relays and connectors shown in the 2nd picture are not original.
As standard the engine bay loom connects to the dash and rear looms with a large collection of bullet connectors in the passenger footwell. Was the engine bay harness that you are replacing an original that has had the bullets replaced by the multi-pin connectors, or had that been rewired too?

Brian.

[HCA]

That is not a Lotus harness. Your car has been rewired at some stage. That harness needs to be ditched and install the one you have. The telays are probabaly re-usable though.

[HCA]

And you will need to change the plugs and sockets for bullets. But I would not be surprised if the interior has also been rewired…

[111Robin]

Thanks, I had my suspicions. Initially I'll retain the multi plugs and use bullets to connect to the new engine bay harness. I hadn't intended on replacing the dash harness but may do so if I can't get this to work. As long as I can trace everything back to the switches and gauges it should be OK. Just takes a lot longer than a straight harness swap

[111Robin]

As I think you already suspect, the relays and connectors shown in the 2nd picture are not original.
As standard the engine bay loom connects to the dash and rear looms with a large collection of bullet connectors in the passenger footwell. Was the engine bay harness that you are replacing an original that has had the bullets replaced by the multi-pin connectors, or had that been rewired too?

Brian.

I had to cut the plugs off to remove the engine bay harness through the bulkhead, there's no obvious splicing of wiring into the loom so it may have been custom made from scratch.

[Andy8421]

Thanks, I had my suspicions. Initially I'll retain the multi plugs and use bullets to connect to the new engine bay harness. I hadn't intended on replacing the dash harness but may do so if I can't get this to work. As long as I can trace everything back to the switches and gauges it should be OK. Just takes a lot longer than a straight harness swap

This will be a challenge. The loom, plugs, relays and fuses look like someone has done a decent job - probably better than the original to be honest, but without a circuit diagram that reflects the wiring, you have to start from scratch trying to figure out what is going on each time you do any work on the electrics. Tracing the circuits through is an easy task in principle, but when cables disappear into a loom, or worse into the rats nest behind the dash, it all gets to be a bit of a mission.

Depending on how keen you feel, you could have a go at drawing out a diagram of the cabling that you have for future reference. It will take time, but in the long run may be a good solution.

Failing that, it may just be easier to replace all the looms with original cabling. Probably not as good electrically as the installation you have, (and a shame to replace what looks to have been a professional job) but it may save a great deal of effort.

[111Robin]

As you say it would be a shame to undo what looks like a decent job. I am replacing the engine bay harness as it's a bit of a mess with paint, spliced connections etc. It will be relatively easy to identify each connection to the two multi plugs. I will then trace the other plug pins to each dash function and draw it out. I've already done this for the relay harness. Admittedly a lot more work but hopefully the best of both worlds in the end. I have tried to remove the wires with pins from the plugs but would probably damage them so I'm just going to use bullets between the new loom and the multi plug tails.

[Andy8421]

The multi pin connectors look similar to Molex power connectors. If so, the pins are easily removed by sliding a tube along the pin that releases tines that locate the pin in the plug. You should be able to find a makers name on the plug, and if you are lucky a part number which should allow you to locate the tool.
Real tooling is expensive, but there are cheap knock-offs that work just as well - if you can find thin wall tubing you can DIY it. I made one using the tubes from an old car aerial.
This tool on eBay gives you an idea of what to look for:

https://www.ebay.co.uk/itm/192196918799?_trkparms=ispr%3D1&hash=item2cbfd43e0f:g:QdsAAOSwfpVZJrQo&amdata=enc%3AAQAGAAACoPYe5NmHp%252B2JMhMi7yxGiTJkPrKr5t53CooMSQt2orsSd3M8ngECaRA0SmyU4KT%252FnqTUj1xJ4loiZYm2%252BRGNclQCY1LEmAt8gWQBR5sqTvjPm8LcWVI4NRZDVbNhCAKS5g0nXmR6dTFRr2mp%252F7AIcjKjxyvuM0MzfMjslTdaotzHZrG2Vr8pL%252BCenzcUVoRQUohHsmRYjolmhaoF2Wmqn95dp02PX4%252Bh73eoRpwMlHffg7ygdjznDK30JmyWZAB3bHp8%252BXsVkGUaIj54eYzwGMs1sFSPZzPHvOsjwwdTZEtwEeGMp47XTNzPOKp6i7YaoNFbcDDfJegxW%252B1tvz09iXar7xG6pF0REyEFzUFGiwznGg94tD4wMtW8BPDma09Bwq8i0gSjiiMwJLjIQwExMkjMqSg0LuyaDL5bCLtdSHNOxESNvXoGd0L%252BqbMfyGg5ZSRPI1oJWENqubhQDIfvRXiu0%252B8v1PZethZveF5PJD5LfC0c9CDMvSERobY%252FD00EjHqnlJ5omzyTMAMSXsn%252FgsZHCocgBOuTxf8srn9CNbVR3DFBJawC%252B45YxzGPfGLBP%252B%252BD%252Bcbz0Oo%252BULkU5IXfXYVe%252F9sCzubdt1UeJ4Bf%252F0zBXl7DTzE%252FTPUyFfYUvdmvOY1Bl5gs2ClACdMqOsmIkDpl%252BoN0YjrTQOYIxrF9%252F2ML0C5VP0djxW9zEYJQUd4I0R7ZcT9Wy7O9eGmDHqCRucoAuLhHadJmBoOqpAd4q89TQpoHze%252FJUEYU7N2FTDf1vcIFzbIQUlzhfrleYjotuZ4VnWhLx4Cyag7CIoghc0YIJAn1s2O2glhbkfIIJvhnUCAClQ9jx8Fq%252FJ%252F7HSGYJPSvbAB83kJ%252Btsm8uwrcE0P1bHWUsM4n5YNj6jD5Qo4aNQ%253D%253D%7Cclp%3A2334524%7Ctkp%3ABFBMsMWc_-tf

[111Robin]

Thanks for that . For now I'll just be connecting to the existing tails with bullets as I don't have the correct ends to crimp onto the new harness.