No electrics at front of van

[Nuggster]

Hey up chaps, I have a bit of a problem, wonder if anyone has had experience of this before I go fault finding as it's quite specific.

I've just fitted a replacement JX engine in the van, all is/was good, no problems with the engine.

Before I fitted the engine there were no issues with starting, or the battery loosing charge, since fitting it I noticed that it seemed to be losing charge, drove it back from the workshop yesterday all good, went to move it today and the battery was almost completely flat (fault No1), went to jump start it and the battery was so flat it still wouldn't turn (at this point everything was still normal on the dash), raised the revs on the car that was providing the jump, turned the ignition key on the van and I'm sure something went fizz and now I have a completely dead van even when I fit a known good battery (no jump),

I have 13 volts at the black box (glow plug relay housing), but by the time it gets to the front of the van I have only 7.5 volts at the feed in on the back of the relay/fuse panel and then only 2.5 volts at the feed into the ignition switch, as I said above I have no lights, no clock, nothing zip zilch, even if I jump the connections across the ignition switch connection. It's got me a bit foxed, I'm an experienced vehicle tech and have never been beaten but this has got me scratching my head, am I missing another fuse link?

[Ian and Lins]

I'm sure someone more expert than me will be along soon but; check and thoroughly clean the two (I don't think there are any more) earth crowns in the dash. It's a well known (once you know it!) problem area and is worth doing even if the problem is somewhere else.

[CovKid]

Its going to be difficult to guess at from afar but bear in mind much of the power to the dash has to go through the ignition switch. Start by tracing wires and see what has burnt/shorted. Also, with battery disconnected, check rear of fusebox carefully for anything burnt/melted.

[itchyfeet]

Sounds like a wire has shorted to the body to me, disconnect batt immediately while you investigate

[Nuggster]

Yep appreciate that chaps, I'm a bit miffed to be honest, I've been in the trade for 20+ years and haven't been beaten before so this is a bit embarrassing for me especially as the T3 is pretty simple.

[CovKid]

If it comes to it you'll have to check from battery through to ignition switch and keep going until you find a melted wire that may be touching the chassis. The only live in the fusebox with ignition off will be for interior lights. The rest doesn't get power until you turn the key. Could just be burnt/damaged cables at switch.

[Nuggster]

That's useful info, cheers

[itchyfeet]

Try disconnecting the multiplugs from the fuseboard, sometimes melted inside and not obvious from visual inspection outside

[Nuggster]

Right then, I've had another delve into it, and can confirm that at the live feed in (red thick gauge wire from loom) to the back of the fuse board I have only 7.5 volts, the same goes for the feed into the ignition switch (which comes from the adjacent terminal to the feed in), also I only have 7.5 volts at the red and white wire that connect to the relay on the inside of the A pillar under the dash (just above the earths).

The last point at which I measure battery voltage (12.5 volts) is on the live stud in the black box that houses the glow plug relay.

I have good continuity on all earths.

The only thing I can think is as above that I have a melted harness somewhere, but that is odd as I would have thought that I would have had battery voltage on one of the 2 live feeds either the red or the red and white, also I have jumped the connections on the ignition switch plug and this does not achieve anything, I would have thought 7.5 volts would have been enough to light the dash LEDs.

From here I think I only have 2 options, either completely strip back the loom til I find the fault or run a separate supply from the battery to the bottom left of the fuse box.

[Smcknighty]

I think the voltage might be a red herring - test continuity through the ignition switch when on, test continuity from the other side of ignition switch to the fuse box live terminals

[itchyfeet]

What make me think it's a short is the loosing of battery charge, typical of high power consumption, couple that with low voltage as one point and high somewhere else says high current short somewhere.
if you have a 10A ammeter on your multimeter and don't mind blowing the fuse go looking for high current draw.
start at the battery should be next to nothing with everything off, then turn ignition on stage 1 only and see what the draw is?
somebody will be able to tell you what a diesel should draw with just ignition on?

[Nuggster]

Fixed, using a bit of logic I thought there was no way that all the live feeds could coincidentally be 7.4 volts being a Westy there s also the live feed under the drivers seat, so it had to be something common to all, so I bridged the battery earth to the body with some mole grips and hey presto I had electrics, so suspect battery earth lead, measured the resistance and it was high, but clearly not so high that it didn't fail test when I checked for continuity of earth engine-batttery, if only I had measured the resistance on Saturday when I tested it (on of the first things I did) instead of just going on the audible pass.

Anyway, I gave the eye end of the strap a wriggle bolted it back on and it's sorted, my only guess is that jumping it must have heated and un-soldered the joint leaving a dry joint, bloody unlikely but it's my only possible explanation, so tomorrow I'll take it into the workshop and re-solder it.

Thanks for all your input chaps, at least I've learn't a bit more about T3 electrics.

[itchyfeet]

So why did the battery go flat?
or perhaps it didn't and you thought it did because of the measurement?

[Nuggster]

So why did the battery go flat?
or perhaps it didn't and you thought it did because of the measurement?

I'm not sure, the earth must have been gradually degrading to the point it wouldn't start, it definitely did so during my fault finding because at the beginning of the process on Friday I had dim flickering dash lights, by the end of Saturday I had nothing at all, very strange and misleading.

I did at least find and prevent another future fault on my way that might be worth other people checking, that is where the loom passes through the rear cross-member just in front of the NSR swing arm there is no grommet and the loom is very tight going through the cross member and it had started wearing through the loom heat shrink, a quick re-wrap and some split down 20mm hose over the loom at that point should prevent any future problems.

[itchyfeet]

If it were my van I would still be poking around with an ammeter to check the current draw when ignition off and on you could have more than one fault and shorts can catch fire.
I don't know what a diesel takes when running not sure if a standard 10A meter is enough?