Fj60 - won't turn off, won't always start (1 Viewer)

[bruegge]

Hi all,
I have an 85 fj60 that has an interesting problem which started a few weeks ago. When I turn the key to off position the engine won't stop, and now will only start intermittently (it currently won't start at all). In the past, I have been able to hot wire it using a jumper to the ignition and start tabs on the back of the ignition switch. I have replaced the ignition switch with a new one - same symptoms. I have tried some ground troubleshooting - no help (that said, I don't see why a bad ground would keep it from turning off).
Not sure if this is a red herring, but letting it sit seems to help...

Thanks for the help.
Ray

 

[3_puppies]

did you replace the ignition switch. key barrel? or the wire assembly on the rear? I would check the wire assembly, as that is where the contacts are located.
also no need to hotwire if the column is opened up and the wire assembly is off, just use a screwdriver in the assembly. still need a key to unlock the column tho.

 

[bruegge]

hey guys, thanks for the reply. I replaced the switch itself (including 10 in wire). Tumbler is fine. My current thinking is that it has to be further down the line (under the dash?). The part I can't wrap my head around is why it wouldn't turn off... I would think that would be an open switch situation, not something bad connections, ground etc would cause. thanks again for any help.

 

[Slow Left]

Pull and test the Ignition Relay (see Body-Electrical Chapter (Chpt. 13) of the 1980 Body-Chassis FSM). See attached for location of the Ignition Relay on the vehicle.

If for some strange reason, the Ignition Relay is stuck 'On', then it will allow current to flow along the yellow path (which is not switched through the Ignition Switch) despite the fact that you have turned the Ignition Switch 'Off' and have removed the key from the tumbler. See image below.

They way it is supposed to work is that when the engine is running, the key has the Ignition Switch in the IG state. In the IG state, the Ignition Switch is allowing current to flow from the battery, through the middle fusible link, through the Ignition Switch, along wire BY (highlighted in red below), through the 5A 'Gauge' fuse and through the inductor (looks like a curly cue, pig-tail like symbol) of the Ignition Relay before going to ground.

The inductor inside the Ignition Relay acts as half of an electromechanical switch. When current passes through it, it creates an electric field that acts to close the other half of the 'switch' (looks like door symbol that opens and closes; along the Yellow path inside the Ignition Relay) of the Ignition Relay. When current stops passing through the inductor (like when you turn off the engine and remove the key from the tumbler), the electric field being generated by the inductor should go away and the 'switch' inside the Ignition Relay should open again.

So, the current that flows along the red path (the current that is controlled by the Ignition Switch) is only used to operate the 'switch' inside the Ignition Relay (to open or close it) by means of the electric field created by the inductor through which it passes through.

The current that passes through along the yellow path is what is used to operate the systems that keep the engine running. As you can see from the diagram below, it draws its current from the battery through a different fusible link than the red path. If for some reason the 'switch' inside the Ignition Relay is always stuck closed (so, always 'On'), then current will continuously be allowed to flow along the yellow path, regardless of the state of the key/Ignition Switch.

Just a theory.

 

[bruegge]

That makes sense. I will swap this afternoon and report back.

 

[bruegge]

So I solved it by replacing the fusable link near the battery (had a spare). I can see why this could cause intermittent starting, but can anybody tell me why this would keep the engine from shutting down? I don't mind good luck, but I'm still scratching my head on the cause...

 

[Slow Left]

Which of the three fusible links was blown?

I can see where a short to ground inside the Ignition Relay would cause the fusible link on the circuit outlined in Yellow to blow. On the circuit outlined in Yellow, the Ignition Relay is in front of the 'Engine' fuse, so it wouldn't be protected by the 'Engine' fuse if there were a short in Yellow circuit inside the Ignition Relay and the current from the Yellow circuit somehow made it to ground.

Or, the fusible link was just old.

 

[Pantingfish]

I have this exact same problem right now except mine shuts off fine. I tried starting it up two days ago, nothing just one click, battery was fine. Then today I was walking by it and saw that the radio was on, got in and it started right up, shut it off just fine. I’m going to take a look at my fusable link near the battery, idk if they’ve ever been replaced is there a way to test them other than just replacing them?

 

[2mbb]

If you hear the starter solenoid engaging (the click) especially if it sounds like it is coming from under the hood, then it could either be bad battery connections or faulty starter solenoid.

 

[Pantingfish]

If you hear the starter solenoid engaging (the click) especially if it sounds like it is coming from under the hood, then it could either be bad battery connections or faulty starter solenoid.

I replaced the starter last year, but it was a rebuilt OEM one so maybe it’s gone bad. I’ll have to check it thanks

 

[Seth S]

If your battery is fine and you are just getting a click when you turn the key its very likely the original wires from the key to the starter solenoid trigger are too old and have degraded enough to have excessive internal resistance. This will create the condition where enough voltage gets to the solendoid to fire it but not enough tto do so completely. The easiest fix for this is to install a relay that is triggered by the factory wiring and connects the battery through a fuse to the starter solenoid trigger terminal. This allows you to use newer larger wires to connect to the starter and deliver enough voltage/amperage to adequately fire the starter solenoid without having to rewire the factory harness. You can use a fender mount relay like some of the older american trucks used or you can use an appropriately rated square relay and mount it where ever makes the most sense.