wierd electrical problems - 12v 3B 40 series

[shorty_f0rty]

Another weird electrical issue. heres a chain of events which might or might not be related since i replaced my tired 3b with a fresher one. the only thing that was swapped was the 3b itself. the glow relays, timers, alternator, etc were all working as they should prior. wirig was not modified at all. intake manifold was replaced due to tapped threads for glowing resistor, wiring, etc. this list is in chronological order.

Situation:
- replaced old 3B with a fresher 3B approx. 2 months ago
- swap over all bolt ons (p/s and 12v Alt)
- then plugged everything in. and it ran fine
- always has started very sluggishly (always needed to crank it heaps to start)
- went to Fraser Island (still cranked slow) but ran fine
- came back from Fraser and +ve battery terminal shows lots of oxidisation (similar to this)
- this is about the 3rd replacement terminal but shows the process in detail, there is more thread on the wingnut to the right at the moment
- check grounds
- replace terminal with brand new brass terminal and monitor (spray with wd40)
- fix what i thought was air in the fuel lines causing hard starts (injector line was soggy)
- massive oxidisation on the new +ive battery terminal

- replace terminal
- discover super glow circuit is only using the afterglow part of the circuit (glow plug receives 5v for 20secs instead of 10v stepping down to 5v)
- check for hot wires off the +ve terminal and notice one of the fusible links gets very hot further along the wire (from the battery)
- trace wires to glow relays and check connections (dont manage to fix glow circuit)
- install wilson switch to allow for manual glowing
- battery terminal is still showing lots of oxidisation
- go 4wding and on the way home voltage hits 15v and the filter light comes on (filter light on usually indicates water in seperator or issues with alternator/charging circuit)
- check and replace fuse in external voltage regulator
- filter light remains on and voltage high
- source brand new replacement external voltage regulator

- filter light remains on and voltage high
- wd40 plugs
- check alternator to discover the wires rubbed and shorted on steering column and have burnt and fused together to the alternator brushes. (see pic)

- replace busted wires and fit new plug, secure wiring so it doesnt rub on anything
- source another 12v alternator and regulator from wreck and installed (needed to swap all alternator internals due to minor bracket differences)
- filter light remains on and voltage low (doesnt get above ~12volts under revs)
- battery terminal now

- wire from plug at back of alternator is extremely hot (too hot to hold) when alternator is running (wire is white with a single black stripe and 2 red rings at intervals)

- currently attempting to trace this wire along its entire path to look for shorts (hard in sealed cable rolls behind the dash)

I have a wiring diagram here: http://www.phat42.com/files/bj42_wiringdiagram.pdf

And from the looks of the 3 wires coming from the alt (the plug i assume) the one marked WB (White with Black) rather than WL (White with bLue) is the hot wire. This wire seems to go to everything! edic, guages, etc.

Can any one offer any suggestions on how to trace or fault find this issue. I think that the high temp in the wires indicates resistance (oxidisation or corrosion/shorts) that could be used to help trace but the temp is hard to find in a big bunch of wires..

any help would be appreciated.

[chimpboy]

I think originally, probably due to the rubbing/shorting wires, your alternator was sensing lower voltage than there really was, so it overcompensated and provided much too much voltage. That explains the battery gunk as well.

As for what's going on now, it's hard to say. All that time with 15V or whatever could have cooked things or damaged wiring.

Are you confident about the condition of the battery? Can you swap a battery in that you know is good? The excess voltage could have damaged it.

[shorty_f0rty]

i have a voltage meter plugged into the ciggie lighter all the time.. it only operates when the vehicle and on and the 15v has only really occured since the filter light came on. (it came on about 2km from home) the voltmeter alerts when over voltage occurs..

it has done minimal driving since then but some. This battery is unknown to me as I swapped it with a mate so he could get home in the dark (busted alt) then forgot to get it back from him before he drove down to syd (im in bris). I have a AGM battery i could swap in but that is all really.

The battery gunk has been occuring since returning from fraser. I dont think the wires were shorted at that time and didnt see excessive voltage on the voltmeter. some times when you turned the key to the glow position you'd here some mad relay's clicking but now there is only 1 relay clicking..

I guess there could be 2 issues here but they could be related..

issue 1) glow circuit (multiple relay clicks,etc busted glow circuit,)
issue 2) hot alternator wires and filter light still on

I think the battery oxidisation is from the busted glow circuit as this would make sense with the hard starting since swapping engine. what would make that occur only on the +ve terminal?

it could be that the wires have worn through else where and are related or are 2 diff issues

[GeneralFubashi]

Thats a complicated story!

The fusible links will get very hot under high load, but that is normal, as long as they arnt blowing. The control wires to the alt usually wouldnt get all that hot though.

How is the main wire from the alternator to the battery? (The one bolted to the alternator, not plugged in) Almost sounds like its not connected and power from the alt is trying to trace back through the field generator wire and the regulator?

Almost sounds like a trip to your local lekky may be in order.

Also, just with the oxidization, you might just try stopping oxygen from getting to the terminal by smearing it with some electrical grease/lanolin grease etc. It makes things more messy, but will give you one less thing to worry about.

[shorty_f0rty]

Thats a complicated story!

The fusible links will get very hot under high load, but that is normal, as long as they arnt blowing. The control wires to the alt usually wouldnt get all that hot though.

How is the main wire from the alternator to the battery? (The one bolted to the alternator, not plugged in) Almost sounds like its not connected and power from the alt is trying to trace back through the field generator wire and the regulator?

Almost sounds like a trip to your local lekky may be in order.

Also, just with the oxidization, you might just try stopping oxygen from getting to the terminal by smearing it with some electrical grease/lanolin grease etc. It makes things more messy, but will give you one less thing to worry about.

yes it is a bit complicated eh.. I've had the issue for a few weeks and after finally getting into it now i find its not as easy as replacing some parts.

The main wire from the alternator is fine. this had previously burnt a plug under the dash and i manually crimped it back together (the plug was melted and had too much resistance to use). i didnt find the cause of this though. i have checked this wire and its intact. I think i recall this wire was hot from the battery previously.. might check that again..

what if that wire is hot at the battery side and cold at the alternator side? that wire runs to the live side of the fuse box and provides power to radio, lights, etc.

fusible links are all ok. I would take it to an auto sparky but thought it was an replace part kinda job.. maybe not.. anyway. id rather spend my time than money tracing wires under the dash.. if i can't get it sorted i'll take it somewhere..

[GeneralFubashi]

i dont have my bj on me right now, so i cant remember exactly how it goes, but the main wire from the alternator disappears into the wiring loom and under the dash, from memory for the sole purpose of having an ammeter.

Just having a look at the wiring diagram you linked to. Our WB coming out of the alternator is the ground wire, thats why its linked to everything. Just making sure this wire is grounded well to the battery, body and engine should fix its heat problem, as its only providing power for internal alternator purposes. WG provides + to the alternator to tell it when the engine is running (Ignition is on). WL from B terminal on alt is the min power wire which goes to: Ignition Key, Ammeter, and Battery (Through fuse wires). As long as you keep a power wire to the ignition barrel, you can run a wire directly to the battery through a fusible link. This will mean the ammeter wont work, but it will also get rid of all that (possibly dodgy) wiring under the dash.
The voltage difference between the two WL wires determines the operation of the regulator.

I usually have great difficulty following factory wiring, cant tell the colours apart. But I'd try bypassing some of the factory wiring. Put plugs on the old loom if you want to keep it, but isolating some of that 25yo birds nest may give you some insight.

btw, the mad relay problem is caused by low voltage at the relay.
Im no lekky, so correct me if im off-base, just going off the wiring diagram.

Sam

[phil94delica]

So you finally managed to kill it. I thought it sounded a bit sick at the 4wd action springs trip.

You probably have a number of issues that all add up to cause major problems.

If you cant figure it out let me know and I can have a look for you. I am getting plenty of practise rewiring 40's lately.

You can try doing a patch job or just give up and rewire the whole thing.

Anyway let me know if you want a hand.

[shorty_f0rty]

had another poke around just then.. i removed the a/c dryer box that sits under the glove box.. the white+blue wire that had melted before looks like its heated up again and needs to be looked at..

i started it up again after removing that a/c dryer box and the 2 stage glow is back.. the single wire thats hot appears to be melting in its plastic sheath. so i'm going to have to trace it from the alternator

the both ends of the big white+blue wire are an ok temp at this stage.. keep in mind im only running this for a few mins at a time

[phil94delica]

If your talking about the big wire that comes from the alternator ( not the 3 little ones) then the best way to fix it is to disconnect it from the alternator and run a nice big wire straight from the alt to the + on the batt. Toyota in all there wisdom ran a pissy little wire from the alternator throught to the dash and then back to the batt, it goes to the Amp guage. Its far too small for the length so once the alternator starts pumping out some decient current it just gets hot and melts.

If it has been shorted then there is a good chance it has stuffed your reg.

[ausoops]

and maybe try a new battery as well, the alt might be feeding an internal short in the battery, causing it to overcurrent/ overvolt.

[shorty_f0rty]

thanks guys it all helps.. i'll have another crack at it tomorrow.

[shorty_f0rty]

Things done so far:
- replaced corroded battery terminal on existing battery and not driven the car. Terminal already shows signs of corrosion without any use (been on there approximately 3 days) I haven't got any dielectric grease yet to insulate the terminal
- checked cell under the positive terminal and looks the same as all the others.
- sourced another battery to use (needs a charge), removed existing battery
- checked continuity on the problem (hot/melting) thin wire from end of the loom that plugs into alternator to external voltage regulator (it has continuity) - White with Black and 2 stripes
- traced hot/melted wire (thin white w/black 2 stripes) through firewall from alt plug and no visible signs of wear. Melted portion only appears to go as far as the firewall and not further.
- checked continuity on thin white with blue and 1 stripe from alt plug to ammeter on the guage cluster (it has continuity)

The melted wire appears to go through the firewall and then joins other white with black wires (1 stripe) and is grounded to the firewall from the inside.

Have not bypassed or replaced any wires at this stage.

Does anyone have any idea what color wires should be where on the plug on the loom side of the alternator? I know the workshop manual has different letters for each part of the plug on the alternator, but the wires coming out of the alternator use a different color scheme that i'm not familiar with.

How can i figure out whats what and that I have correctly wired up the replacement plug (I'm pretty sure its right but want to be certain)

The slow cranking/starting issue could be related to a seperate issue (timing on the 3b) which im investigating seperately. At this stage I just want to get teh filter light off, stop the wires from melting and get a proper charging system again.

[chimpboy]

Is there any chance that wire is shorting to the body at the firewall? Just wondering since you said it looks melted up to the firewall but no further.

[shorty_f0rty]

Is there any chance that wire is shorting to the body at the firewall? Just wondering since you said it looks melted up to the firewall but no further.

That was what I was suspecting.. I unwrapped the loom completely all the way to, and through the firewall and the wire that is melting didn't have any bare spots (as if it rubbed raw on its way through the firewall).. When I traced it, that particular wire grounds itself to the body under the dash and is spliced into the main ground wire for all other components that are part of the loom.

I'm suspecting I wired the plug I replaced wrong BUT I am certain I replaced one wire from the plug at a time as to get them in the correct spots...

[shorty_f0rty]

right.. well i had a play with the plug i'd replaced tonight to try and get ready for a call in regards to what wires go where.. in doing so i discovered that the crimped parts of the plug weren't crimped as well as they could of been therefore being relatively easy to pull the wire off the connector from inside the plug.

the bits that werent crimped properly are similar to the metal bits in this pic


If this was the case (bad connection inside the plug) would it be enough resistance to melt and heat up the wire?

I have since recrimped the wires and will be looking to use the old plug because its a tighter fit. I'm no auto sparky so i'm not sure if this would be enough to contribute to the melting wire..

[phil94delica]

A bad connection will create alot of heat if there is a decient amount of current flowig through it. I have replaced switch boards in houses that have caught on fire due to loose connections.

You can get a proper crimp tool for those uninsulated lugs, I got mine from dick smith for about $20 and it works a treat.

[shorty_f0rty]

thanks phil.. I've got a decent set of crimpers and have redone them with considerable force so I dont think they will be coming undone any time soon..

After getting a hand to confirm my wiring of the plug against 1 other bj42 I found that white+black and white+blue wires were around the wrong way in the plug. I'm hoping to get further confirmation from other bj42 owners that this is the right setup before i start the 40 again...

first is with it plugged into the alt plug

bottom is white+black
top is white+blue
and under is white+green

and this is with it unplugged

so the top flat wire is white+black (horizontal)
closest is white+blue (vertical)
furthest is white+green (vertical)

[GeneralFubashi]

if the rest of the wire is fine, its not going to get hot due to a faulty plug, unless the wires in the plug are shorting against each other. The plug however will get super hot and deform/melt/catch fire. Wires can get hot enough to melt if they have high current and no-where to disperse the heat too. So if the wire is taped into a loom or running next to other hot parts its not going to be able to get rid of all that accumulated heat.

[shorty_f0rty]

i guess if the ground wire (the one that was getting hot/melted) was getting some current (when it shouldn't have) then that could explain why it was getting hot (contributed by a dodgy connection?) i only tried it briefly when it was doing that so maybe thats why the plug didnt melt. when it was still taped into the loom it was melting to other wires..

[phil94delica]

From memory 99% sure. With that 3 pin plug, the bottom wire in the plug if you look at the plug like this

l l
_

the bottom is a ground, neg which is the white with black stripe ( I think, just use a meter to check)

The top two dont matter in the way that if they are reversed it just wont work, it wont damage anything if you give it a test run. If it charges then you have it right, if it doesnt charge just swap them over and it should work. As long as you dont mix one of the top two with the bottom - tive wire then it wont hurt to try some trial and error.

That 3 pin plug only has a small amout of current flowing through it uder normal operation so if its getting hot then something else is wrong.