Truck doesn't start...

[allofthisforyou]

I think your battery ground cable is not grounded properly or faulty. The arcing you got when you hooked it up is due to resistance and your parasitic drain or short in your electrical system. Do you have the body, engine, frame, and battery all grounded?

The negative terminal connects to the negative battery post (ground) at one end and a thick cable attaches the terminal to the frame. The engine is connected to the frame (grounded), but I don't know about the body... The main circuit seems alright but I'll re-trace it again over the next couple of days because obviously I must have missed something...

I just took the alt. in for testing and it was fried. Apparently it's a 2-wire alt. as well (although it was hooked up as a 1-wire alt.)... Either the people at that shop don't know what they're talking about or this alt. was never working... The regulator and stator are being replaced tonight and it's getting turned into a 1-wire alt.... Since my alt. is hooked up something like this: battery------(main positive wire)------('branch' off of main +'ve wire)------alt.--------(negative wire)--------frame., and since the alt. was (apparently...) a two-wire alt. is it possible that the electricity was running through the alt. and that was the short circuit (I'm not very knowledgable about this kind of stuff so if that doesn't make sense that's why)??

I tried starting the truck without the alt. in it (both with an "open" circuit where the alt. was and with a closed circuit (I connected the "+'ve" cable that was running to the alt. to the "-'ve" one) with two different batteries but I get the same result: when I turn the key to "START" the only thing that happens is the headlights dim (I don't hear the click of the starter)... I'm guessing that means that the starter, or some fusible link is blown (it should be possible to start the truck without an alt. right?)? If so, does anyone happen to know where the fuse for the starter is in these things? I don't have an owner's manual or a FSM and my fuse box attached to the body panel (under the steering wheel) is missing its cover... I checked the LC user’s manual on the Bauchan website (bj42lx_um.zip) but it didn't seem to list a fuse for the starter... Is it in-line, somewhere else, or is it in that fuse box (and that manual just doesn't cover 74's)??

Thanks for that link bsmith123 (it might come in handy one day), and sorry Coolerman (and anyone else who might have been confused by the voltage dropping to 0-2V): my voltmeter goes from 8-16V so that "0-2" should have been "8-10"...

p.s. The other battery I used was only showing about 10V on the gauge, so it might not have been a surprise that it wouldn't start the truck, but it starts the van I pulled it out of regularly so I figured it’s a "good" battery (I don't know if FJ40's need more volts to start but I figure a 12V system is a 12V system)...

p.p.s. would diode failure/'poping' be louder than a Chev. 283 V8 revving at around 2500 rpm?? I'm starting to think I should have written 'pop' as 'bang.'

Thanks for all the help and I'll keep you posted.

 

[bsmith123]

http://www.globalsoftware-inc.com/c...ics/FJ40/1978FJ40/1978fj40_wiring_diagram.pdf

This schematic is for a 78 but shows the diodes and a fusible link--I dont know the config of a 74 but some things will be true for any alt circuit


""""a two-wire alt. is it possible that the electricity was running through the alt. and that was the short circuit (I'm not very knowledgable about this kind of stuff so if that doesn't make sense that's why)??""" YES

this is just a way to look at it without getting into electron flow and other stuff to confuse the issue----

an alternator makes AC and the diodes turn it into DC. With AC current runs both ways it reverses back and forth -- neg to pos and pos to neg, with DC it runs one way

the diodes make up a bridge rectifier---here's a good explanation
Diode bridge - Wikipedia, the free encyclopedia. The DIODES make the AC run one way.

But, yes if the diodes break down and allow reverse voltage to flow you get a "hot" ground wire if they go open then all flow stops either way. In a DC system reverse flow is going to be a short.


It is not necessarily just the diodes it could be a short or a fuse problem now. Current will flow to the path of least resistance but if you were pulling so much that the starter wouldnt turn then I think you would be smoking wires. I think the damage is already done.


Really a multi-meter and a few checks is the way to a solution instead of worrying about the noises and symptoms. As long as you have looked it over for physical damage, melted wires, blown fuses.


you could start with the wires on the solenoid--- one should have power with the key in run and the other with the key in start. If neither has power start working your way back from there. Better yet leave power off and shoot continuity since you suspect a short.

for shorts-----any wire that runs between components should not read resistance to the frame or batt neg cable with the components disconnected

For continuity- with the wire disconnected from components and one end held to a ground on the frame (or use a lead with test clips to ground it) should read a low resistance to ground


you can also shoot for resistance but in your case I think you will find opens and shorts


A test light can work too---if a wire is disconnected at both ends and the light lights ---that is a short! (make sure all components on the wire are disco'd though)


If you do have a short you just want to be a little careful eh? if you fix a blown fusible link or a fuse or worse bypass it with wire you could be smoking some stuff


It sounds like you know how it works but maybe not a lot of experience t/sing electrical circuits---its easy to show someone but harder to explain w/o doing that so I hope I am making sense to you.

Bottom line is to troubleshoot you have to test and eliminate---"troubleguessing" is a lot more hit and miss

If you can do it safely you can also figure a lot out by disconnecting the circuits old wire and running a bypass wire ---basically a new wire in place of the old temporarily

but like i said be careful and make sure you know what you are doing so you dont start burning it up!

If you cant find a schematic to match just start drawing your own as you go along.


I hope that helps a little, best of luck I know it can be frustrating

 

[bsmith123]

diode

here this might help. Of course might not be the diodes at all I am just trying to explain that one possibilityView attachment 283784

 

[71 redwood]

kragen has a alternator 45 amp for $39- ......I also have a 283 .60 over keith black flat top, polished,dished,2.02 camels, but im not running it in the Fj..Hmmmm might just do that., it is sitting on an engine stand collecting dust an spiders,,,, also check your distributer cap for a bad crack

 

[allofthisforyou]

Thanks for the schematic, the info. on diodes bsmith123 (it was insightful), and all the circuit testing how-to. What's up with the ignition switch labelling in that schematic though?? Shouldn't the ST and ACC be switched around?? The way I understand that diagram is that the 'radio circuit' is closed when the key/switch is in the "ST" position and the 'starter circuit' is closed when the switch is in the "ACC" position. Maybe it's just me though Anyways, if that schematic is applicable to my FJ40 then I guess I can rule out the fuse blowing (since it seems that there is only one fuse in the starter circuit and it's in series with the ammeter (my ammeter is functioning)).

The alts. been rebuilt. The diodes were fine, and the only things that needed replacing were the regulator and the stator. Could either one of these two things failing have been the cause of that that 'squeal' and 'bang'?? I'm not worrying about the noises and symptoms I just want to make sure that it is reasonable to conclude that what I heard was caused by one of those two things failing (like you said bsmith123, there is an explanation so SOMETHING must have been making that noise (I figure it was either something mechanical/rotating was under stress (the 'squeal') and finally let go (the 'bang'), or something mechanical was causing the noise but it lost power (fuse blowing, etc. (the 'bang')), but I guess it could have been just about anything). The woman at the shop told me that the alt. I pulled out of the truck was a two-wire alt. and so, since it was setup as a one-wire, it had me asking myself "wouldn't that mean the alt. wasn't activating when the truck was turned on/running?" If that was the case, then wouldn't the only thing that could "go" be the pulley, or bearings, or something like that (things being moved by the belt)?? Since the only things that needed replacing were the regulator and stator, I just want to make sure that it's reasonable that these things, or something related to these things, were/was responsible for the noises I heard. If not, then there might be something else that I should have to look at before I tackle the (re)wiring (the distributor seems to be fine)...

Unfortunately I forgot to take the battery with me when I was picking up the alt. (to get it load tested), so I can't confidently conclude that the starter/wiring is at fault, but it seems fine... I'll try jump-starting the truck again--while giving it a little gas this time (I don't think I did that last time)--as well as try to start it up regularly, with the rebuilt alt. installed but it's probably a waste of time.

I'll pull the starter over the next few days (if I get the chance) and test it/get it tested as well. If the starter's fine, and if a battery load test check out, I'll tackle the wiring. I'll probably take the truck in to get rewired properly (a place that specializes in wiring will probably do a better job at locating shorts and opens, identifying bad wires, and replacing wires that need to be replaced than I would on my own) but it would be nice to know that the wiring is the only problem left (it'll probably be easier for them to do the job if they can get the truck started at the end of the day).

Thanks for all the insight and I'll let you know how things progress over the next few days/weeks.

beer: to the 283 71 redwood... I'm sure you'll enjoy the extra power (especially if you're ever pushing 37's ))

**I'm not too sure what to make of the turn signals, and brake lights coming back on, and I'm even more confused by the hazard lights beginning to function... I removed + reinstalled (didn't replace, since there was no apparent need, just took them out and put them back in) a couple of the fuses in the fuse box so that is the only explanation I can come up with but it's still strange.

 

[71 redwood]

someday I might put that baby in there but,,,I'm try'n to stay "OG" for the investment an the thrill of owning a "TOYOTA LANDCRUISER FJ40 " bone stock..........maybe a lift or a header,,,but nothing else.....

 

[allofthisforyou]

someday I might put that baby in there but,,,I'm try'n to stay "OG" for the investment an the thrill of owning a "TOYOTA LANDCRUISER FJ40 " bone stock..........maybe a lift or a header,,,but nothing else.....

Right on... OGs definately seem to be worth the investment (if they're in good shape)... Personally I like the way these things look on 37's, and with a bikini top, but that's just me

Anyways, here's an update: the battery works fine under load, the starter was pretty badly fried, and four teeth on my flywheel are pretty badly worn (by about 1/8 of an inch--see attached pic)... I'm gonna replace the starter with a rebuild and see if it'll turn the engine. If not then I'll look into the wiring...

 

[bsmith123]

ring gear worn

ring gear--- You know you can change just the gear right?

you are right the acc and st is swapped on the schematic

you have three wires on your alt

F E B B is battery, E is earth (ground) and F is field for voltage sensing in the V/R. What do you mean set up as a one wire? Converted to a one wire or a wire was left off of it accidently?

 

[allofthisforyou]

Sweet... No, I didn't know that but thanks for letting me know (I'm sure it'll save me some money).

It's possible that one wire was accidently left off of the alt. by the PO but I've never seen a loose "F" wire in the engine so I figure it was converted to a one wire set up but a two wire alt. was installed by mistake. I guess we'll see once I get this thing started up again...

Would the electrical system have to be converted to 'one-wire' though? Isn't the difference just in the alternator? I read somewhere that the difference between a "one-wire/self-exciting" alternator and a two-wire alternator is that a one-wire alternator just needs to be hooked up to the battery and ground (because it has a special voltage regulator in it and, thus, doesn't need an ignition wire to activate it (source: frequently asked alternator questions)).

 

[allofthisforyou]

Alright, I replaced the alternator and starter with rebuilds and I managed to start the truck three or four times without any problems. The arcing at the neg. terminal seems to have decreased substantially as well. There is slight sparking when I connect the neg. terminal but not anymore than in any other vehicle I own or have owned. I don't know whether the faulty alt. could have been the cause of the drain so I'll leave the truck parked, with the battery connected, for the next few days and monitor the battery's charge. I'll post up again with the results but I'm hoping I won't have to post up to much more about this .

Thanks for all the help, and Happy New Year.