1974 fj 55 only runs in start! (1 Viewer)

[n2666s]

taught in shop about 1/2 century ago that gap meant no connection BUT Toyota does things its own way like JIS vs DIN so am adding a picture showing the "gap" circled in red and welcome any comments

 

[n2666s]

Mark; on wiring diagram don’t see a wire that could be an “exciter” wire going to coil from I.switch

 

[Steamer]

EDIT: Deleted the poor pics to post this better one. With the legend.

 

[n2666s]

Would either of these help? There's no years marked on them & I don't have knowledge of the model lettering.
I could try to take better/larger pictures of'em.
View attachment 2679321

big thank you Steam; don't know differences between the series though, will have to do some research; still trying to figure this one out think the V means Van = commercial vehicle designation for Japanese market; but fj55 LG ???

 

[Pin_Head]

You can Turn the engine using a wrench on the alternator nut and pulling the belt tight.

You don’t need to have the points closed if you just ground the - side of the coil.

The crossing lines on the schematic that you circled are probably not connected because if they were they would habe different color codes, which would mean that they are different circuits.

The “exciter” wire that bypasses the ballast resistor starts at the starter solenoid as a pig tailed connector and goes to the + side of the coil. It is a smaller diameter black wire with yellow stripe.

Remember that the ignition circuit is not fused, so it is not a headlight problem.

If your headlights don’t work, this could be related because all circuits get power from the battery through the amp meter. Does any circuit have power? If not check connections at the amp meter and at the fusible link (if you have one). You can’t tell it is good by looking at it. Measure the voltage with the circuit on and powered.

 

[Steamer]

I replaced the above pics with a better scan. Don't know if it's the right diagram, but it shows the ignition circuit as fused.

 

[n2666s]

perfect; big thank you again

You can Turn the engine using a wrench on the alternator nut and pulling the belt tight.

You don’t need to have the points closed if you just ground the - side of the coil.

The crossing lines on the schematic that you circled are probably not connected because if they were they would habe different color codes, which would mean that they are different circuits.

The “exciter” wire that bypasses the ballast resistor starts at the starter solenoid as a pig tailed connector and goes to the + side of the coil. It is a smaller diameter black wire with yellow stripe.

Remember that the ignition circuit is not fused, so it is not a headlight problem.

If your headlights don’t work, this could be related because all circuits get power from the battery through the amp meter. Does any circuit have power? If not check connections at the amp meter and at the fusible link (if you have one). You can’t tell it is good by looking at it. Measure the voltage with the circuit on and powered.

P_H another thank you for so much help and advice over the years; cleaned up the fuses, holders and connectors in fuse box and now headlights work ; the headlight issue was what started this dilemma ; will get under the pig and get to the starter and its wiring to check voltage in and like your guidance on grounding negative side of coil ;
Lou

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[Travis 76]

Sorry if you have already figured this out. My 76 had the same problem turned out to be a bad coil resistor. I bypassed it and it ran fine. Replaced it and that fixed the problem.

 

[n2666s]

OK still beating my head ........... fuse box and wiring look pretty beat maybe I need to put in a NOS that I have stashed but ALL the fuses test OK with the multimeter; hate to put a new one in if can get the old one to work; in pix of the back two spade connectors that are empty/not connected to any wires?; comments?; IIRC the wiring diagram doesn't show them ; will be checking engine compartment again while I have daylight

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[n2666s]

this is why she wouldn't crank maybe can go deeper into the "runs only in start" issue


repaired loose connector now back to square 1; maybe 1 1/2 cause have headlights now .................runs and cranks beautifully when in start BUT dies when switch returns to run/on

 

[LandCrusher'70]

this is why she wouldn't crank maybe can go deeper into the "runs only in start" issue

View attachment 2681501

Uhhh, yeeeaaaahhh...

 

[Pin_Head]

It is hard to know what is going on with the fuse block by just looking at the picture. There is some corrosion where it doesn’t matter. Where it matters is on the connectors for the plugs and fuses.

I hate to keep harping on it, but the fuse block is not the problem for your ignition because the ignition is not fused. The power comes from the battery fusible link to the amp meter and from there to the ignition switch and then the fuse block.

 

[n2666s]

It is hard to know what is going on with the fuse block by just looking at the picture. There is some corrosion where it doesn’t matter. Where it matters is on the connectors for the plugs and fuses.

I hate to keep harping on it, but the fuse block is not the problem for your ignition because the ignition is not fused. The power comes from the battery fusible link to the amp meter and from there to the ignition switch and then the fuse block.

P_H; big thank you again; I appreciate your input and guidance tremendously and don't consider it harping just steering adjustments its a process of elimination and don't have a very reliable wiring diagram also don't have the usual fusible link; it does have a fusible link but it goes to the electric power steering

 

[n2666s]

any idea where does this black wire comes from ?; it shows on the 1974 pig wiring diagram going to or coming from negative side of coil which also doesn't show a ballast + have two wires coming out of the coil negative only one shows on the wiring diagram? am bumfuzzled ; am assuming the solid black one goes to distributor cap and the red and black???.......ignition key in on/run position the old Simpson reads 12 volts going into ballast + 9 volts out and following P_Hs thoughtful advice with the coil grounded still reads the same
ONLY RUNNING IN START OR HOT WIRED but starts and runs sooo smoothly hot wired from battery to coil + or through key side of ballast .

 

[Pin_Head]

Picture linky no worky.

The black wire at the distributor is probably the wire between the points and the - side of the coil.

If you have 12V at the ballast resistor and 9V at the + side of the coil with the ignition on and the - side of the coil grounded, then that is normal and the engine should run. If you push start it , it should run fine. I’m thinking it has to be an oddball problem with the switch itself that either grounds the ignition wire when you let off of the start switch or it interrupts the power to the coil. I would bite the bullet and replace the switch and hope for the best.

 

[n2666s]

Picture linky no worky.
P_H redid the pix; hope they worky now
The black wire at the distributor is probably the wire between the points and the - side of the coil. yep; it is solid black; will test for continuity tomorrow and no mention of color on the wiring diagram or of a red/black wire coming off negative side of coil. BUT it is transition model with the 1 1/2 F engine

If you have 12V at the ballast resistor and 9V at the + side of the coil with the ignition on and the - side of the coil grounded, then that is normal and the engine should run. If you push start it , it should run fine. I’m thinking it has to be an oddball problem with the switch itself that either grounds the ignition wire when you let off of the start switch or it interrupts the power to the coil. I would bite the bullet and replace the switch and hope for the best.

replaced the old switch with a lovely NOS from ToyotaMatt as recommended but is doing the same as the old one; runs in start or hotwired will get to it again in the morning

 

[n2666s]

Sorry if you have already figured this out. My 76 had the same problem turned out to be a bad coil resistor. I bypassed it and it ran fine. Replaced it and that fixed the problem.

Travis; good observation; pretty much think have ruled out a bad resistor as when tested it is doing its job reducing the voltage from 12 to 9; there is a gremlin hiding somewhere

 

[Steamer]

A jumper like this would bypass what’s in between them and also test what’s on either end.
You could probably get an alligator clip on that switch terminal.

 

[n2666s]

A jumper like this would bypass what’s in between them and also test what’s on either end.
You could probably get an alligator clip on that switch terminal.

View attachment 2681878

Steamer; just did your suggestion and hot wired her from the switch she starts and runs sweetly but dies as soon as take off clip there is something very screwy lurking here underneath

 

[Steamer]

Without a good diagram you may have to just physically trace it out. Sounds like a bad connection somewhere.

Does that same switch terminal feed more than ignition? Is anything else that runs only with ignition on, not working, like the radio or turn signals?

How about the connection between the new switch and existing wiring. Maybe disconnect it and jump from there.