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Makotosun

1978 DT400E Wiring Harness in very sad condition

  • cdr
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Hello All,

The main trunk wiring harness on my 1978 DT400E is missing the stock connectors and looks it has had multiple band aid type repairs.

I would prefer to replace this harness instead of trying to fix multiple problems on the existing harness.

Can someone on this forum direct me to another source for this harness?
I would even be willing to consider a used harness if it is in good condition and still has the stock connectors. 
 

 
Last edit: 21 Oct 2022 19:25 by cdr.
21 Oct 2022 19:24 #1

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Check with DEET. He makes new harnesses for many models, not sure if he does the 78.
1963 YG1-T, 1965 MG1-T, Allstate 250, 1970 CT1b, 1971 R5, 1973 AT3MX, 1974 TS400L, 1975 RD350, 1976 DT175C, 1976 Husqvarna 250CR, 1981 DT175G, 1988 DT50, 1990 "Super" DT50, 1991 RT180, 2017 XT250
21 Oct 2022 20:24 #2

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Hello MarkT,

I did check with DEET earlier today.
He indicated that he does not make harnesses for the 1978 DT400.
21 Oct 2022 21:24 #3

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There have been a couple people here with either multiple monoshock 400's they were trying to make into one bike or multiple harnesses....  MSAVITT may have been one of them.

Forum searches might take a little time to dig through but you might find someone that has an extra. 

78 was different than 77.  Mostly headlight no longer had an on-off switch in 78.  You should be able to make either work but would need other parts possibly. 
1963 YG1-T, 1965 MG1-T, Allstate 250, 1970 CT1b, 1971 R5, 1973 AT3MX, 1974 TS400L, 1975 RD350, 1976 DT175C, 1976 Husqvarna 250CR, 1981 DT175G, 1988 DT50, 1990 "Super" DT50, 1991 RT180, 2017 XT250
21 Oct 2022 21:56 #4

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Replied by Gr8uncleal on topic 1978 DT400E Wiring Harness in very sad condition

That harness might well be repairable and not as bad as it looks, as long as you're happy crimping on new bullet connectors.

If it were me, I would disconnect all the wires in the headlight bucket, remove them from the bucket and then take the bucket off completely. This will give you so much more space and light to work in.

New bullet connectors, covers and other tools are available from Vintage Connections.

Vintage Connections - Motorcycle Terminals and Connectors - Vintage Connections

Your hardest job is likely to be finding out which wires had male and which had female connectors - CMSNL, Partzilla, ebay and the internet in general will be your friends for this. Partzilla and CMSNL will give you part numbers of the electrical components, CMSNL might have some photos, ebay might have the items for sale, for which there might be multiple photos and you can just do an internet search for photos of the items. View as many different photos as you can, as some parts on fleabay are incorrectly listed.

Once you are happy you know which wires have which connectors, fit the new ones in place. Post here if you want any tips on crimping. On the male connectors/wires, it wouldn't do any harm to fit a half inch or so length of heatshrink material over the wire before you crimp on the terminal. Then slide this back over the rear end of the terminal and heat until it is nice and snug and gives a nice cover of insulation. I use Gr8auntiepat's old hairdryer!  

I would then connect all of the wires back together, without the headlight bucket in place, to give it a "dry run" and see if everything works as it should. When it does, disconnect the wires, fit the bucket, route the wires back into the bucket and re-connect them.
22 Oct 2022 00:15 #5

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Replied by Gr8uncleal on topic 1978 DT400E Wiring Harness in very sad condition

"I did check with DEET earlier today.
He indicated that he does not make harnesses for the 1978 DT400."


Yes, I did think that 1978 might be a bit modern for DEET! 

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22 Oct 2022 00:17 #6

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The general rule on connectors is the side that is providing the power at that point gets a female terminal.

The wire that you are plugging in to be powered gets a male terminal.

That way, if a component is disconnected you won't have a potentially "hot" wire with a male end floating around that can easily short to ground.

For example a turn signal has a male connector that plugs into a female connector in the harness.
1963 YG1-T, 1965 MG1-T, Allstate 250, 1970 CT1b, 1971 R5, 1973 AT3MX, 1974 TS400L, 1975 RD350, 1976 DT175C, 1976 Husqvarna 250CR, 1981 DT175G, 1988 DT50, 1990 "Super" DT50, 1991 RT180, 2017 XT250
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22 Oct 2022 07:38 #7

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This chap supplies DT looms to
order. Not sure about US spec, but you could ask?
alans-electrics.alanlowe.co.uk/yamaha-stock
 
25 Oct 2022 09:23 #8

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Hi All, Mark has a great memory.
I bought a 1978 DT400E with a 175 front end...and a really nasty wiring harness.
Nasty meaning no way I was going to fix it, chunks missing, connectors cut off, so I found a 1977 DT400 harness on eBay in really nice shape for $40, which made me feel good about other overpriced parts I bought for this model. And as Mark pointed out, the '77 was wired for headlight on/off, the '78 not. But since I knew this (thanks Mark) and because my left handlebar switch was smashed, when I bought a replica from somewhere in SE Asia (it was incredibly nice BTW), I got one with the on/off and H/L.

If harness is really hacked up, then I would go find one on eBay. A 250E should work too, but for having to probably tweak things a bit due to 400 having CDI and 250 points
26 Oct 2022 14:04 #9

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