73 FJ40 Won’t Start

[Nolacajun75]

Definitely sounds like the ignition switch, but is it possible that the wires got mixed up?
Disconnect the switch, and check continuity at each position.
Turn it to the start position and measure the contact resistance

Just curious but how can I possibly mix the wires up? What wires? It's just a plug. Are there any wires on back of the dash that could have been reversed or changed causing this problem? I did just rewire up my dash but did one wire at a time to make sure they were all in the same spot and the problem was before this and after this

 

[45Dougal]

Yea sometimes connectors get the wires mixed up.
Sometimes different models use different pins in the same connector. Worth checking

 

[Nolacajun75]

Yea sometimes connectors get the wires mixed up.
Sometimes different models use different pins in the same connector. Worth checking

How would you recommend I check this? I'm not sure what I'm looking for

 

[mattressking]

To quickly diagnose your issues and skip all the nonsense....

1. Unplug ignition switch harness.
2. Take your multimeter and probe the CHASSIS SIDE of plug with multimeter on continuity.
3. Find the terminal that has continuity to the starter solenoid plug (chassis harness) so disconnect from starter.
4. Once you find continuity, put 12V on that terminal to bypass ignition switch OR make a jumper on the chassis side of ignition harness plug from +12v constant to the terminal you just probed.
5. Does starter spin? Y/N.
6. Report back.

 

[45Dougal]

To quickly diagnose your issues and skip all the nonsense....

1. Unplug ignition switch harness.
2. Take your multimeter and probe the CHASSIS SIDE of plug with multimeter on continuity.
3. Find the terminal that has continuity to the starter solenoid plug (chassis harness) so disconnect from starter.
4. Once you find continuity, put 12V on that terminal to bypass ignition switch OR make a jumper on the chassis side of ignition harness plug from +12v constant to the terminal you just probed.
5. Does starter spin? Y/N.
6. Report back.

My understanding is that it does spin.

The issue seems to be either a bad switch, bad switch connector, or a miswired switch

 

[mattressking]

My understanding is that it does spin.

The issue seems to be either a bad switch, bad switch connector, or a miswired switch

I’ll let the owner confirm, don’t need hearsay .

He needs to confirm wiring to starter all works properly before people throw out ‘replace replace replace’. My test is quick and confirms what’s needed, if it works as expected and starter doesn’t spin with key, then a quick continuity test of ignition switch is next - then verify pin out. But that’s AFTER.

 

[Nolacajun75]

To quickly diagnose your issues and skip all the nonsense....

1. Unplug ignition switch harness.
2. Take your multimeter and probe the CHASSIS SIDE of plug with multimeter on continuity.
3. Find the terminal that has continuity to the starter solenoid plug (chassis harness) so disconnect from starter.
4. Once you find continuity, put 12V on that terminal to bypass ignition switch OR make a jumper on the chassis side of ignition harness plug from +12v constant to the terminal you just probed.
5. Does starter spin? Y/N.
6. Report back.

Yes I did that and it does turn over when I do that. I also checked from that pin. It goes to the black wire with white stripe and the wiring all rings out good. What do you think

 

[45Dougal]

I’ll let the owner confirm, don’t need hearsay .

He needs to confirm wiring to starter all works properly before people throw out ‘replace replace replace’. My test is quick and confirms what’s needed, if it works as expected and starter doesn’t spin with key, then a quick continuity test of ignition switch is next - then verify pin out. But that’s AFTER.

If you read the preceding posts, it is clear that jumping a 12V feed onto the BW wire at the ignition switch (which feeds the solenoid) causes it to spin as expected.
Either the feed to the ignition switch is compromised, or the ignition switch is not working (or wired incorrectly).
Maybe this helps in case you don't have it already (toyota wiring diagram is best in my view).

As you'll see, all pins should be connected together when the key is turned to "Start".
What colour wire does your Black-Yellow connect to at the ignition switch connector on the harness side?
I think this is maybe where the mistake lies

 

[DeskJock]

He just replaced that ignition switch. I think Nate is on the track. The male and female plug that he used is also suspect. I’ll also add, check the fuses, clearly it’s been rewired - could have a fuse inside the factory harness or outside the factory harness.

 

[Nolacajun75]

My understanding is that it does spin.

The issue seems to be either a bad switch, bad switch connector, or a miswired switch

This is a problem that started slowly as intermittent then now it just don't start at all. Just click click click so it's not just an instant problem that popped up. Yes it does turn over if I jump directly to the starter or jump power directly to the ignition switch. See below

 

[Nolacajun75]

I’ll let the owner confirm, don’t need hearsay .

He needs to confirm wiring to starter all works properly before people throw out ‘replace replace replace’. My test is quick and confirms what’s needed, if it works as expected and starter doesn’t spin with key, then a quick continuity test of ignition switch is next - then verify pin out. But that’s AFTER.

Well I put a new starter in and because I thought it was bad at first but obviously it wasn't. The truck ran and started fine for the last 2 years so there's no wiring issues that that could cause this. If it's been fine for so long, I didn't change any of the wiring. So not really sure.

If you read the preceding posts, it is clear that jumping a 12V feed onto the BW wire at the ignition switch (which feeds the solenoid) causes it to spin as expected.
Either the feed to the ignition switch is compromised, or the ignition switch is not working (or wired incorrectly).
Maybe this helps in case you don't have it already (toyota wiring diagram is best in my view).

As you'll see, all pins should be connected together when the key is turned to "Start".
What colour wire does your Black-Yellow connect to at the ignition switch connector on the harness side?
I think this is maybe where the mistake lies

View attachment 3663111

But how is there a wiring problem now if it's been working for the last couple years? That's what I don't see. The only thing I changed is the ignition switch when it comes to any wiring and it's just plug and Play and the wires seem to be matching up and the part number is correct. I'm definitely not seeing something here while doing something wrong. I'm not sure what but....

 

[45Dougal]

Ignition switch connector is about all that's left then - maybe take a very close look at those crimp terminals

 

[Nolacajun75]

Ignition switch connector is about all that's left then - maybe take a very close look at those crimp terminals

Okay, I'll run jumper wires to ensure a good connection and see what happens. I'll report back tonight. I really appreciate it

 

[DeskJock]

Ignition switch connector is about all that's left then - maybe take a very close look at those crimp terminals

and the plug connections, which, Nate's instructions will help understand that issue.

I've kinda lost track of what worked and what didn't. did routing positive 12 volts to the solenoid cause the starter to engage and turn the engine?

 

[73FJ40]

I replaced the relay same problem there. I jumped from one side of the starterlay solenoid attached to the firewall to the other side terminal and it did turn over. Did not click like it's been doing. Randy, wire directly from the battery to the small wire on the starter turns over, not clicking. Checked resistance and continuity of wires going from relay to battery relay to starter. All good. 13. Volts at battery at one side of the relay and at the starter.

Problem still clicking no starting. Any ideas what I can check next? I don't see anything burned or kinked anywhere. I'm missing something somewhere simple. I know it.

. The only thing I changed is the ignition switch.

@Nolacajun75

Post 27 (quoted) states you replaced the "firewall mounted solenoid" so it's not only the ignition switch you replaced.

That solenoid has no business being there, and you noted in #27 the truck turned over when you jumped it.

With all the non-OEM looms under the hood, you really need to sort out how that solenoid fits into the picture.

 

[Nolacajun75]

and the plug connections, which, Nate's instructions will help understand that issue.

I've kinda lost track of what worked and what didn't. did routing positive 12 volts to the solenoid cause the starter to engage and turn the engine?

Yes it did turn over perfectly when I go direct

 

[Nolacajun75]

@Nolacajun75

Post 27 (quoted) states you replaced the "firewall mounted solenoid" so it's not only the ignition switch you replaced.

That solenoid has no business being there, and you noted in #27 the truck turned over when you jumped it.

With all the non-OEM looms under the hood, you really need to sort out how that solenoid fits into the picture.

Yes I agree with all that. And I did change other parts but with no change in problem.

So if I remove that solenoid, is the OEM stock way of wiring the starting system going to be the fusible link from the battery direct to the ignition switch and then the ignition switch throws that power once the switch is turned to the solenoid small wire on the starter. Is that correct? Does that make sense? If so, I'll just rewire everything And get rid of the solenoid. I didn't know if all that amperage is going directly through the column ignition switch

 

[Aussie Alaskan]

Yes I agree with all that. And I did change other parts but with no change in problem.

So if I remove that solenoid, is the OEM stock way of wiring the starting system going to be the fusible link from the battery direct to the ignition switch and then the ignition switch throws that power once the switch is turned to the solenoid small wire on the starter. Is that correct? Does that make sense? If so, I'll just rewire everything And get rid of the solenoid. I didn't know if all that amperage is going directly through the column ignition switch

Barely any amperage is going thru the ignition switch. All the ignition switch does is trigger/trip the starter solenoid (on the starter) by giving the small wire on your starter 12V. This 12V trips the solenoid. From there, the big wire on the starter (goes directly to the battery positive post) provides the power for the starter to turn the engine over.

Sounds like you are not getting 12v to the small wire on your starter via the ignition system. You've manually jumped it and it works. But you can't get power from the yellow/black wire on your ignition switch to the small wire on your starter. Only two things are between that black/yellow wire (which you've said gets 12v as it should) and the starter solenoid.
1. The ignition switch itself.
2. The starter solenoid wire. (Small wire on the starter)

The ignition switch is probably fine since you've replaced with a new OEM unit, but you can double check.
But the starter solenoid wire should be checked for continuity. You may have a short in that wire that kept getting worse and finally lost continuity.

 

[45Dougal]

The starter solenoid takes a good few amps to throw, especially when they're old and tired. It's also a big electromagnet (inductor) so current lags behind voltage, which can cause the ignition switch to arc.

While the bulkhead relay (not solenoid, since its only function is to actuate another set of electrical contacts) is not original, its not a bad upgrade in a system which is known to have a weak ignition switch.

While some of the wiring needs tidying up, it looks like some effort has been made.
I'd recommend printing out the toyota diagram as a starting point, and then editing it to bring into line with what you have.
You'll probably find that it's not actually that much different, and then decide what to do.

FWIW, my money is on a corroded ignition switch connector wire/terminal

 

[Nolacajun75]

Barely any amperage is going thru the ignition switch. All the ignition switch does is trigger/trip the starter solenoid (on the starter) by giving the small wire on your starter 12V. This 12V trips the solenoid. From there, the big wire on the starter (goes directly to the battery positive post) provides the power for the starter to turn the engine over.

Sounds like you are not getting 12v to the small wire on your starter via the ignition system. You've manually jumped it and it works. But you can't get power from the yellow/black wire on your ignition switch to the small wire on your starter. Only two things are between that black/yellow wire (which you've said gets 12v as it should) and the starter solenoid.
1. The ignition switch itself.
2. The starter solenoid wire. (Small wire on the starter)

The ignition switch is probably fine since you've replaced with a new OEM unit, but you can double check.
But the starter solenoid wire should be checked for continuity. You may have a short in that wire that kept getting worse and finally lost continuity.

The wires all check good for continuity. I guess I can unplug the ignition switch and make jumpers so I know that the connections are touching and see if that helps, but I doubt it. I'll try that tomorrow. I need to go buy some connectors