44GPW Posted March 11, 2012 Share Posted March 11, 2012 Hi guys, About to embark on the task of re-wiring my Bedford MWD and wondered if anyone out their has done this, and can offer any do/don'ts and tips? Can't decide whether to strip out all the old wiring first, or change wire for wire? I have a wiring diagram and the new loom has been made up to the same colour code. Also, where is the best place to start? Engine bay, instrument panel or rear end? Anything else i should be aware of? Any help very much appreciated. Thanks Richard Quote Link to comment Share on other sites More sharing options...
Pete Ashby Posted March 11, 2012 Share Posted March 11, 2012 Hi guys, About to embark on the task of re-wiring my Bedford MWD and wondered if anyone out their has done this, and can offer any do/don'ts and tips? Can't decide whether to strip out all the old wiring first, or change wire for wire? I have a wiring diagram and the new loom has been made up to the same colour code. Also, where is the best place to start? Engine bay, instrument panel or rear end? Anything else i should be aware of? Any help very much appreciated. Thanks Richard If you have the wiring diagram I would strongly recommend that you remove all old wiring first and check and clean all switches and contacts before you install the new loom, that way if you should have a fault/open circuit you have limited the number of options for the fault. I always start by laying the new harness component parts out on a clean board so I can have a look at where the loom branches come this will then dictate how you go about fitting it into the truck for instance you don't want to be pulling a loom with a number of branches up the length of the frame rails when it's better to take it back the other way and limit the amount of snagging and pulling.... obvious... but in the excitement you can end up trying to stuff three branches and a 1" dia main loom through a 1/2" firewall hole... it just wont go!. You'll be fine take your time check the wiring diagram against the new loom colours before you start for each run of wire, also check the connectors/terminals are the same on the new loom as the old, they should be but sometimes they aren't and it's easier to change/modify things on the bench rather than trying to do it upside down under the dash panel. I tend to start with the long runs first as that lets you bring circuits up to the firewall/bulkhead and then join everything up by doing the dash wiring, depending on the type of vehicle your'r working on it can also be the most difficult as you end up standing on your head jammed under the dash, but it's up to you really. Oh one last thing do not be tempted to connect the battery to test a circuit before all the looms are in place, securely connected and you have double checked with the diagram that everything is in the right place, another obvious thing to say but it only takes 3 seconds for a whole loom to become a smoking shrivelled mess when you find that you have missed a live feed that just happens to have earthed out on the bodywork somewhere up under the dash/frame. If you want to check continuity use a meter with a beeper and a couple of spare long wires £10 from Halfords as opposed to £350 ++ for a new loom Pete Quote Link to comment Share on other sites More sharing options...
44GPW Posted March 11, 2012 Author Share Posted March 11, 2012 Pete, Thanks for that, really helpful stuff there. It's on a Bedford MW so the dash wiring should be a bit easier. One question, if I get a meter and do a test, exactly where am I running wires from to test the full circuit? Cheers Richard Quote Link to comment Share on other sites More sharing options...
Pete Ashby Posted March 11, 2012 Share Posted March 11, 2012 Pete, One question, if I get a meter and do a test, exactly where am I running wires from to test the full circuit? Cheers Richard For example if you want to check line continuity clip one flying lead from the meter onto the terminal/wire you want to test, the other flying lead from the meter goes to to the switch/terminal, turn the switch get a beep. The thing to keep in mind is everything needs to go from the power source through the item (light whatever) then to earth via the frame. Use you wiring diagram and trace the line from start to finish if you have a problem connect the meter across each and every junction/switch in turn when you don't get a beep that's the area where the fault is. There's nothing magical about earth return systems it's all about logical thought and actions do everything in sequence and don't be afraid to make notes it can save hours of going round in circles. Pete Quote Link to comment Share on other sites More sharing options...
44GPW Posted March 12, 2012 Author Share Posted March 12, 2012 Hi Pete, Thats great, thanks. Spent a good 3 hours this weekend with the loom on the dining room table, and using a 1940 wiring diagram as a reference i labeled up every wire end with where it goes and checked that both ends agree with the diagram. This will help me when i do it, and i'm also happier as i understand it more now. Only issues are that the loom only has provision for a single Tail and stop light, as the original, so i will need to take a feed to the other side of the body for a second rear light, and there is no provision for the indicator flashers that i have fitted in the cab, but i will just leave the wiring to them in situ, then renew once the loom is in. Not used a meter before, will it be obvious what setting to have it on? Thanks Richard Quote Link to comment Share on other sites More sharing options...
Pete Ashby Posted March 12, 2012 Share Posted March 12, 2012 Hi Pete, Thats great, thanks. Spent a good 3 hours this weekend with the loom on the dining room table, and using a 1940 wiring diagram as a reference i labeled up every wire end with where it goes and checked that both ends agree with the diagram. This will help me when i do it, and i'm also happier as i understand it more now. Only issues are that the loom only has provision for a single Tail and stop light, as the original, so i will need to take a feed to the other side of the body for a second rear light, and there is no provision for the indicator flashers that i have fitted in the cab, but i will just leave the wiring to them in situ, then renew once the loom is in. Not used a meter before, will it be obvious what setting to have it on? Thanks Richard That's the way, three hours spent at your dining room table will save you many more frustrating ones in the workshop. As for your second feed to the other tail and stop these can be made with soldered bullets and double female connectors ie live feed to tail light in one end of the female double then take feeds to tail lights left and right out the other end, just repeat the process for the brake light feeds make the connections where they will not be subjected to road spray, inside the frame rail is always a good place, you could for a couple of pounds buy a closed junction box and locate it on the frame rail, everything stays dry but not very period your choice. Do not be tempted to use modern scotch locks they just look naff. As for your meter there are various types of multi meter on the market have a look at e-bay for price rang for your needs get a cheaper one they all come with instructions that make the various functions clear but I would advise getting one with a continuity beeper as it makes it easier when working in tight spaces. Also buy a couple of mini cocodile clips some meters come with them (e-bay again if not) as it will let you clip your flying leads onto ends of wires/switches ect without the need for 15 foot long arms. Pete Quote Link to comment Share on other sites More sharing options...
44GPW Posted March 12, 2012 Author Share Posted March 12, 2012 How does this one look to you? http://www.ebay.co.uk/itm/DIGITAL-AUTOMOTIVE-MULTIMETER-car-engine-analyser-CE-/350244544293?pt=UK_Diagnostic_Tools_Equipment&hash=item518c339f25 Quote Link to comment Share on other sites More sharing options...
Pete Ashby Posted March 12, 2012 Share Posted March 12, 2012 How does this one look to you? http://www.ebay.co.uk/itm/DIGITAL-AUTOMOTIVE-MULTIMETER-car-engine-analyser-CE-/350244544293?pt=UK_Diagnostic_Tools_Equipment&hash=item518c339f25 That's the sort of thing it's a bit posh you can get them cheaper for what you want to do with it. The symbol with the loud speaker (bottom) is the one for sound continuity. Pete Quote Link to comment Share on other sites More sharing options...
44GPW Posted March 12, 2012 Author Share Posted March 12, 2012 I like "Posh"....we still have Salt and Pepper out every dinnertime Thanks for you help....much appreciated. Richard Quote Link to comment Share on other sites More sharing options...
rippo Posted March 12, 2012 Share Posted March 12, 2012 (edited) Hello Richard, I have a new loom in my bedford. By the looks of it it is similar to yours. I did not fit mine, yet, i've taken it out as part of the restoration, so will be putting it back in, in the next few months. Regarding the rear lights, the wiring in mine, does not go straight to the rear lights. From the front it runs down the chassis to a junction box on the back of the bottom crossmember of the body, then from there to the rear lights, two sets of wires come from the box instead of one. Here's a picture of mine when i got it, there are to many wires as it had a caravan hitch on it when i got it, I think these junction boxes are a standard fittment on mw's, i'd have to check my books to be sure. Also some mw's were fitted with a socket for trailer lights, this would also come from this junction box. Does your new loom have the wire for the dif light on? Maybe you can help answer some question i have? Can you take some pictures of the live and neutral wires from the battery to show how they run and where to, i'm pretty certain the live goes straight to the starter, but i'm not sure where the neutral should go. Where are the other earth straps fitted to complete the curcuit? Engine to chassis? and the chassis to the bulkhead? and is there an earth strap to the front panel? Or any others? I did also be grateful of some pictures of where you loom runs, just for a referance with your being an original one. Thanks John Thanks Edited March 12, 2012 by rippo Quote Link to comment Share on other sites More sharing options...
Pete Ashby Posted March 12, 2012 Share Posted March 12, 2012 I like "Posh"....we still have Salt and Pepper out every dinnertime Richard Well done that man!!, good to see standards are being maintained, I have to remind the Butler to do the same some times......you can't get the staff these days. Pete Quote Link to comment Share on other sites More sharing options...
Pete Ashby Posted March 12, 2012 Share Posted March 12, 2012 Hello Richard, I think these junction boxes are a standard fittment on mw's, i'd have to check my books to be sure. [ATTACH=CONFIG]58906[/ATTACH] Hello John You are right, those Junctions are standard fitments on most British WW11 trucks made by Lucas if I remember right?. They turn up on e bay from time to time or from the specialist vintage suppliers like Paul Beck. Regards Pete Quote Link to comment Share on other sites More sharing options...
44GPW Posted March 12, 2012 Author Share Posted March 12, 2012 Hello Richard,I have a new loom in my bedford. By the looks of it it is similar to yours. I did not fit mine, yet, i've taken it out as part of the restoration, so will be putting it back in, in the next few months. Regarding the rear lights, the wiring in mine, does not go straight to the rear lights. From the front it runs down the chassis to a junction box on the back of the bottom crossmember of the body, then from there to the rear lights, two sets of wires come from the box instead of one. Here's a picture of mine when i got it, there are to many wires as it had a caravan hitch on it when i got it, I think these junction boxes are a standard fittment on mw's, i'd have to check my books to be sure. [ATTACH=CONFIG]58906[/ATTACH] Also some mw's were fitted with a socket for trailer lights, this would also come from this junction box. Does your new loom have the wire for the dif light on? Maybe you can help answer some question i have? Can you take some pictures of the live and neutral wires from the battery to show how they run and where to, i'm pretty certain the live goes straight to the starter, but i'm not sure where the neutral should go. Where are the other earth straps fitted to complete the curcuit? Engine to chassis? and the chassis to the bulkhead? and is there an earth strap to the front panel? Or any others? I did also be grateful of some pictures of where you loom runs, just for a referance with your being an original one. Thanks John Thanks Hi John, I have two wiring diagrams one dated Nov 1940 and the other July 1942. Interestingly, the early diagram does not show wiring for the Diff light whereas the 1942 diagram does. My loom does not have it and also has the wires for the dimmer switch which I do not have, so been made from an early diagram. I will be able to get some photos of the old loom in situ at the weekend before I remove it, but according to both diagrams, the live and natural from the battery go to the starter. The N feed earths on the rear engine support. The problem with the wiring in my MW is that the old loom has been left in place, and in areas cut off and new wiring added, so there is twice as many wires then there should be. A real mess. What is still in use of the original loom is in such a poor state, I rekon it could burn at any time. Its that bad that I probably won't use it until the wiring is replaced. Anyway, will get you some picks on Saturday. Is the junction box you pictured fitted next to the diff switch on the rear cross member? Cheers Richard Quote Link to comment Share on other sites More sharing options...
rippo Posted March 12, 2012 Share Posted March 12, 2012 Hello pete, yes that is right, thinking about it the headlamps are wired in the same manner, the main loom goes to a junction box then either two or one wire to the lamps. I am correct all mw's were wired this way, the parts list states, Chassis number- 1001-39692, Box 4 way junction, rear cross member, part number. Lucas 770069 Chassis number 39693- , Box 2 way junction, rear cross member, part number. Lucas 770028 including: COVER.2-way junction box MT4/lu/770033 Regards John Quote Link to comment Share on other sites More sharing options...
rippo Posted March 12, 2012 Share Posted March 12, 2012 (edited) Hi John, Is the junction box you pictured fitted next to the diff switch on the rear cross member? Cheers Richard On mine the junction box is screwed to the back of the last wooden cross member, just above the tow bar, and it is the bigger 4 way junction box, i have no holes in my chassis for the dif light switch or junction box. I guess the junction box was moved to the chassis when it was changed for the smaller one, there it is more exposed so maybe why it has a cover? Anyone ever seen a cover for one? In the parts list i have it says the live goes to the starter switch, but it doesn't say for the neutral, on yours does this go to the starter mounting bolt? Then an earth strap from the engine nount to the chassis? But what earths the bulkhead? Regards John Edited March 12, 2012 by rippo Quote Link to comment Share on other sites More sharing options...
44GPW Posted March 12, 2012 Author Share Posted March 12, 2012 John, I will see what mines like on Saturday, but the 1940 wiring diagram lists all the Earths as follows; Headlamps Generator to LH Side Member Starter to Engine Rear Support Controller to footwell top panel Rear lights Richard Quote Link to comment Share on other sites More sharing options...
44GPW Posted March 14, 2012 Author Share Posted March 14, 2012 Been thinking about the best way of re-connecting the wires on the instrument panel and am thinking about using a short piece of wire on each terminal with a bullet connector, then a connector on the cable from the loom. Then, instead of trying to get to the small slotted screws of the connectors, its just a case of pushing the bullet connectors together. Anyone else done it this way or does anyone see a problem with this? Thanks Richard Quote Link to comment Share on other sites More sharing options...
Nudge Posted March 15, 2012 Share Posted March 15, 2012 Been thinking about the best way of re-connecting the wires on the instrument panel and am thinking about using a short piece of wire on each terminal with a bullet connector, then a connector on the cable from the loom. Then, instead of trying to get to the small slotted screws of the connectors, its just a case of pushing the bullet connectors together. Anyone else done it this way or does anyone see a problem with this? Thanks Richard As long as you fit the right connectors, then it does make life easier. (by 'right' i mean if the loom has a 'male' fitting, you fit a 'female' to the wire, sounds obvious now, but its a pain when your upside down under a dash wondering why your connectors don't fit ....... (cough ..........not that i'd know about that ......... cough .......:blush:) Quote Link to comment Share on other sites More sharing options...
44GPW Posted March 25, 2012 Author Share Posted March 25, 2012 Finished today and everything worked first time so very pleased. Just got to fit the new rear lights then I will add some photos to my "Bedford MW" post. Quote Link to comment Share on other sites More sharing options...
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