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Davo

Rewire recommendations

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Hi,

i have b reg car pinto engine and donor parts from a Sierra gl. I put a new mot on it yesterday so I’m all ready for summer driving. 

 

But it I do have an intermittent electrical problem. Some times you turn the key and just get nothing. No start. No lights. Only hazards. Leave it 5 minutes or poke the harness under the dash and suddenly you’re back on again. 

Interestingly I lost power on the way to the mot station 3 times yesterday, each time at a junction. 

From this complex diagnosis I reckon there’s probably something loose under the dash. 

But with all the fancy wiring from a Sierra it’s really messy under there with tape and all sorts. 

So a little part of me just wants to put in a complete new loom. It can’t be that complex right? Switched power to the starter, coil and each of the lights and you should be almost there right? Lol. 

I am pretty terrible at making connects etc, so in an ideal world I’d want a kit with just the minimal with all the lighting pre terminated. Does such a thing exist? Any recommendations? 

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3 hours ago, Davo said:

So a little part of me just wants to put in a complete new loom. It can’t be that complex right? Switched power to the starter, coil and each of the lights and you should be almost there right? Lol. 

Aha, aha, that is funny....not. 😁

Looms are IMO the most difficult and weird part of the car - press the horn and the wipers come on - WTF?! This is reflected in the price - GBS charged me £400 for the main loom and then wanted a further £500-ish for the engine and dash looms. I got the main one and then made my own for the rest but it was a slog and I don't fully understand what I did for all of it 😉. I've also had a few issues since which I'm sure are down to my incompetence.

I believe there is a company called Premier Looms which people have used happily.

Be aware, however, that just getting the loom made is 10% of the job - installing it is a pig and may well involve the car being completely stripped down - I think I would rather start a new build from scratch 😉

As to your original problem, if it helps, I had the same thing. The cause was my starter motor - the 12V terminal had come loose and a wire had snapped internally, which meant that sometimes, when that flapping wire deigned to make contact, the starter motor worked but other times, nothing. Details in my blog - here

 

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As above - if you're savvy (or willing to put large amounts of effort in to learn) then making your own loom for these cars is not difficult. I just made mine from scratch, spent time designing it and it pretty much worked first time bar some minor tweaks to a few final circuits. People want convenience these days, and boy do companies charge for it. Premier Looms are as good a solution as anywhere; I think I've seen mixed results on here and through word of mouth but ultimately, if you don't know the right end of a diode from the wrong one and "blowing a fuse" is what your missus does when she finds engine parts in the dishwasher  - best go that route ;)

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So thanks to you both. I dread the thought of stripping down but equally I can’t work with the snakes nest of useless wires under the dash. 

So tell me if this is completely bonkers.... I can’t stand the thought of starting the complete job and biting off more than I can chew and never finishing. The lights and accessories all work; most of the time. Would it be crazy to have two looms in place until I’m ready to completely strip out the old. Could I just put in the new; connect up only to a new key or starter button, the starter motor and distributor, and just disconnect the old from those component so at Least I have a car that reliably starts, and then gradually moving lights etc onto the new loom throughout the winter? Mad? 

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Honestly? Just rip it all out and start again. Trying to "meld" two looms together is more hassle than it's worth (yes, I've done it!) and in the long run you'll have a neater solution if you just replace the whole lot - it will be consistent (what I mean is, no second guessing in the future "where does this go" or "what does that do" or "why on earth did I wire this that way" !!). Do it right and do it once, rather than trying to save time/money/effort in the short term for more hassle and cost long-term. Well, that's my opinion anyway ;)

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yeah, sounds a bit dubious that - I have sort of done that in a minor way; my oil pressure gauge didn't work and I traced it to a break in my loom somewhere from the oil pressure sensor, so I just added a separate extra wire from the gauge to the sensor, bypassing the main loom.

But that's a minor part of the electrics which wasn't working at all - trying to add an extra bit in to a semi-working section seems fraught with danger, especially as you didn't put it in yourself in the first place, so you have no real idea of how it's currently wired.

If I was in your shoes, I'd spend a bit of time checking all the connections (because that's where my problems have always been), looking for damage, bent terminals, wires that pull out of plugs with a gentle tug etc. Sometimes, just disconnecting and reconnecting a plug can dislodge some crud which was preventing a signal. Use a multimeter to check for breaks in the wires themselves (I've never had that as a problem but none of my wiring is more than 3 or 4 years old).

If none of that helps and you aren't driving the car anyway so making it worse isn't an issue, then I would probably don my cowboy hat and do as you say - add some more spaghetti 😀

 

Edited by nelmo

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To me ripping it all out because of a few loose connections might be a bit drastic at this stage. If it is all working when you jiggle the wires then it is just a likey a loose connection as mentioned above.

If there is a big mess of wires just cut each one to the correct length and either put a new connector on it or resolder the orginal connector back on. once you are happy just re-wrap them all together neatly. This is how i did mine with the original sierra loom. There is still a bit more than is needed under the dash but it is pretty well sorted otherwise as everything fits into the standard ford stuff so the electronic ignition module just plugs in as normal and i don't have to worry about trying to get this or that to work on a different loom etc. You also have the advantage that the haynes manual has a fully colour coded schematic so if you really needed to you could get someone else to work on it.

If that then still doesn't work pull it all out and replace with a new loom.

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1 hour ago, agent_zed said:

To me ripping it all out because of a few loose connections might be a bit drastic at this stage. If it is all working when you jiggle the wires then it is just a likely a loose connection as mentioned above.

If there is a big mess of wires just cut each one to the correct length and either put a new connector on it or resolder the orginal connector back on. once you are happy just re-wrap them all together neatly. This is how i did mine with the original sierra loom. There is still a bit more than is needed under the dash but it is pretty well sorted otherwise as everything fits into the standard ford stuff so the electronic ignition module just plugs in as normal and i don't have to worry about trying to get this or that to work on a different loom etc. You also have the advantage that the haynes manual has a fully colour coded schematic so if you really needed to you could get someone else to work on it.

If that then still doesn't work pull it all out and replace with a new loom.

I second this as the wiring is a minefield and it's better to use details that somebody else has put together than fully start from scratch. I took the route of following the Ford wiring and now all the colours/uses roughly follow the Haynes schematics the difficulty for me was that the original loom was Ghia spec. so had many sections that were superfluous to requirements(there are still relays that do nothing but i'm too scared to remove). My engine wiring was easy as it just overlaid the Sierra so just followed separate details.

As my kit was Westfield I could have used their loom which was much simpler and in hindsight may have been a better bet, certainly easier.

My wiring however took a few years to complete as I had little spare time whilst working and trusted the job to so called experts(3) who messed things up, took ages and stung me for bodged work, since retiring I completed the work.

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There’s a Westfield wiring loom on eBay that might be a good solution for you. You’d have to adapt it for the Sierra terminations and possibly extend some cables. 

Item no 143348898855

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Someone in the club rewired mine for me. If I had it done earlier I would have been on the road a year before I actually was but my loom had been cooked due to position after an engine type change. I would start be redoing all the dash connectors as it would be a cheap and easy fix if it worked. The new loom was the end to my electrical problems though. 

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Thanks for all the help. 

I think partially unrelated but the battery is dead which is causing a few problems first. 

Last of the crazy questions though, if I were stuck whilst out because of the intermittent fault, if I were to put 12v from the battery to the distributor and then 12v to the relay on the starter motor to start it, would that work to get me home? Admittedly I’d have no lights etc but would that be enough? 

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Depends on your setup. It'll be the coil that needs 12v not the distributor as such. My setup has the original electronic ignition which has a small module that I guess would need power and i also have a weber carb that has a fuel cut off solenoid on the carb that needs 12v. If you hve an electric fuel pump that would also need electric. Not sure if my autochoke would cause issues without 12v.

I'd try and find the cause of the intermittant fault if i were you.

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Apologies... your right12v to the coil. 

Its a very simple set up as far as I know. The choke is completely manual. The fuel pump is mechanical only. 

I think there is a starter module but it’s beyond me what it does. Maybe to do with an old ballast wire. 

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A require of the ignition on a Sierra is pretty simple. I have recently done it on mine as my fuses were melting when using the headlights as the whole system was pretty much run on 2 fuses... Pre builder fail...

Do you use the ignition barrel / key to start the car or do you have an ignition switch / push button setup? I have a push button and you could rewire the ignition system in about 30 mins from scratch if you needed to with one of them. So simple. Happy to run you through it if you need.

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