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Kingcab

720 king cab healights/dahlights dont work

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So I have a 82 720 and the healights work but they are very dimm the driver side is super dimm and when u turn on the high beem only the passenger side works and also the dash lights dont turn on and the cigarette lighter doesn't work.. what would cause all this? And is it all linked together?.. 

 

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If the truck has been sitting a long time all kinds of strange and fascinating things happen to the electrical system, mostly due to corrosion. Start by cleaning/replacing your headlight plugs.

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 Check the running/parking lights are they off as well? If so get them working first and this will fix the dash lights. You also need dash/running lights to power the hi/low headlight relay so that might also end up being fixed as well. The two fuses closest to the front of the truck are for the headlamps.

 

Check/clean your battery posts and cable terminals and look on the positive cable for your fusible links. (usually black and green wires) If any looks all burnt or crispy replace it.

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Physically test the fuses.  I have had several of the blade fuses look good but not have continuity.

 

There are fusible links connected to the positive battery cable.

 

720_Fusible_Link_1.jpg

 

720_Fusible_Link_2.jpg

 

720_Fusible_Link_3.jpg

 

83_720_Fusible_Link.jpg

 

Nissan_Fusible_Link_Amperage_Color_Chart

 

Mike any pictures of burnt fusible links?

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I cleaned all connections running lights work fine. But only the dash loghts cigarette lighter dont work and the headlights are dimm and when I turn the high beems on all work besides the driver side inside light. I've checked all fuses and wires on the fusebox and the relay is branew. 

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If the side marker, license, running and parking lights are working then the dash lights are disconnected somehow. Did you turn the dash light dimmer switch to full brightness???? Is the dimmer plugged in? Under the steering column are two 10 pin connectors near each other, one white and one blue (maybe green) Unplug and plug back in..... maybe the connection is poor to the dash.

 

 

Not following the headlight statement. What happens when headlamps are turned ON in the low beam position??? What happens when you switch to HI beams????

 

Do you have stock headlamps or after market????

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I've changed the diner switch with a new one and I took off my cluster and cleaned all connections going to the back of it. When I turn on headlights they are dim and when I turn on high beem they are also dim but the driverside inside one doesn't work only they are also stock headlamps. I'll have to follow out every wire and see if there a broken wire somewhere as I noticed theres an old rat nest in on of the vents.

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Have you cleaned grounds?

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11 hours ago, Charlie69 said:

Have you cleaned grounds?

I was just about to say that. My truck was really clean when I got it but some of the grounds had to be cleaned; definitely check those! 

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The headlight circuit on the 720 wiring harness is a weird animal, yes you need to check your grounds, but you cannot add any grounds either.

First check to make sure the headlight plugs on the outside headlights are plugged in properly, if one is upside down it will cause issues as it puts a ground where it is not supposed to be.

Next, do you have aftermarket gauges or radio in your truck, if you do and someone wired the gauge light in it to the headlight or dash light circuits this could be your issue as this light needs to be wired in properly, neither the headlight or dash light circuits have a traditional ground, aftermarket gauge lights normally ground out to the gauge housing, this is a ground that is not supposed to be there, if one follows the wires in the stock aftermarket gauges in headlight or dash light circuits you will only find grounds before the headlight relay and at the dash light dimmer control switch, stock gauges are in plastic housings.

On the 720 diesel wiring harness the only ground wires in the plastic instrument cluster are for the seat belt and clock circuits, even the high beam indicator has no ground, it is wired into the headlight circuit without a ground because them wires are after the headlight relay, I do not know if the tach on a gas wiring harness has a ground wire.

One can wire the aftermarket gauge lights to the marker light circuit, as it does have a traditional ground, but you need to find out which wires they are behind the dash, they will be wrapped up but one does have access at the blue and white plugs and at the plug connected to the headlight switch in the column clamshell.

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Great info Wayno!

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Thanks for the info guys! I'll chek ibto all this when I get the chance and I'll keep you all posted on what I find out 

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Another question unrelated.. but I was wondering if the timing chain xover from the z22 would bolt on to the l20b..

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Timing cover? Yes, perfectly, but the top part under the head isn't a perfect match. The shape and the bolt holes don't match, but as this only seals in oil spray and fumes you could probably seal it up without them. .

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