How to kill an ignition coil?

[mrt6644]

I had some strange electrical issue recently where it looks like the ignition stayed on for a week and killed my battery.
After jump starting the vehicle it ran very poorly.
Is it possible I damaged the coil?
What are the symptoms of a damaged ignition coil?

 

[Slow Left]

FJ62?

Have you run the On-Vehicle Inspection procedures (see 3F-E FSM...page IG-5)? The procedure has a series of tests, including test for the coil.

I'd also check the corresponding fuses in the main fuse panel to make sure they are good...

...and you could run a 'mis-fire' test...while engine is idling, separately and individually detach each HT wire lead at it's spark plug...if you don't hear a deterioration in the idle with the HT lead detached, there is mis-fire going on in that cylinder...trouble shoot further for that cylinder

 

[Slow Left]

I had some strange electrical issue recently where it looks like the ignition stayed on for a week and killed my battery.

Have you identified why/how the ignition remained on for so long? What was the problem?

 

[Slow Left]

What are the symptoms of a damaged ignition coil?

The coil amplifies the voltage from the battery...from 12 Volts to thousands of Volts...and sends it down the HT spark plug wires where it jumps the gap at the spark plug...if the coil is bad, it won't be able to generate enough voltage to jump the gap and there will be no spark.

More than likely, an engine won't run at all with a bad coil. It's kinda like there is either spark and it goes or there is no spark and no goes...but if you run the trouble shooting tests outlined in the FSM, that can easily rule out the coil from causing the symptoms you are noticing...

 

[mrt6644]

FJ62?

Have you run the On-Vehicle Inspection procedures (see 3F-E FSM...page IG-5)? The procedure has a series of tests, including test for the coil.

I'd also check the corresponding fuses in the main fuse panel to make sure they are good...

...and you could run a 'mis-fire' test...while engine is idling, separately and individually detach each HT wire lead at it's spark plug...if you don't hear a deterioration in the idle with the HT lead detached, there is mis-fire going on in that cylinder...trouble shoot further for that cylinder

Thanks! All great suggestions.
The Vehicle has run perfect since I got every thing running well, but now this.

 

[dylans]

I was having issues with the idling and drivability in general, after replacing a ton of stuff, I turned to the coil, pulled the original out, and WHOA. The case was almost rusted through, it was leaking fluid, and the nuts on the terminals were so corroded, I had to cut them off to detatch the igniter. 1 new coil and some cleaning later. Bam, truck ran great. This was in my fj62 BTW.

 

[Slow Left]

Yeah, guess you could also check to see if it's throwing a code...

...if the IG tests all test out OK, then you've got to be thinking the poor idle has got to do with the EFI system.

But you've still got to find the cause for why/how the ignition remained on for so long, if indeed that was the case and if it caused the battery drain.

 

[mrt6644]

I rewire a bunch of things. I did a modified version of the window relay fix, I rewired door locks, added fresh power leads, etc.
Something I did caused power to be fed to one or more of the factory power groups.
The batt light stays on when the key is off so I know something is up.

 

[Dynosoar]

leaving the key "ON" is a good way to kill a coil.

Dyno

 

[dylans]

leaving the key "ON" is a good way to kill a coil.

Dyno

On that note,for the first 3 MONTHS of my ownership, I didn't know I had to press that button on top of the coloum to let the key go to off. It sat in acc 100% of the time. Went through a battery. Shame on my stupidity :'(

 

[TobyB]

Drive it for a while. Killing the battery wipes the limited amount of 'learning' the ecu can do.

That's probably not it, but worth eliminating... meanwhile, go through all the tune- up things
you'd normally do. I found a distributor that had been full of water for quite a while...

t

 

[FJ40Jim]

No, the electronic ignition is self protecting. If the key is on but the dissy is not spinning, the coil will receive power, but will not see a ground, so no current actually flows through the coil.

On an old fashioned points system, if the engine was not turning and the points were closed, then coil cooking would result.

 

[mrt6644]

Drive it for a while. Killing the battery wipes the limited amount of 'learning' the ecu can do.

That's probably not it, but worth eliminating... meanwhile, go through all the tune- up things
you'd normally do. I found a distributor that had been full of water for quite a while...

t

I'm hoping this is the issue. I've seen this ecu learning concept before.
When I was originally fixing all of the issues, every time I would make a significant change, it seemed like the engine had to adjust and eventually start to run better. Weird for such an old engine.

 

[Slow Left]

Do you have a multi-meter that can measure in the range of 10-20 Amperes?

If so, what you could try (in order to narrow down where - which circuit - the parasitic drain is coming from) is the following:
1) with the engine off (and all components, like lights etc. - don't forget the door light! - off), disconnect the neg battery cable at the neg battery terminal
2) with multi-meter set to measure Current (in the range of tens of Amperes), connect the multi-meter in line between the neg battery terminal and the recently removed neg battery cable terminal (make sure that the contacts are solid and don't accidentally ground on the chassis)
3) does the multi-meter measure a current? If so, what is that value?
4) if multi-meter is reading a current greater than ~25mA, go to the fuse panel (multi-meter is still in series) in the vehicle cabin and pull each fuse one at a time individually, and with each fuse out, go back and see if the current reading at the multi-meter has gone back down to 0. If so, then the circuit for which that fuse is removed is the culprit...and can further troubleshoot the wires/switches/components/grounds in that circuit to find the 'leak'...

 

[mrt6644]

Do you have a multi-meter that can measure in the range of 10-20 Amperes?

If so, what you could try (in order to narrow down where - which circuit - the parasitic drain is coming from) is the following:
1) with the engine off (and all components, like lights etc. - don't forget the door light! - off), disconnect the neg battery cable at the neg battery terminal
2) with multi-meter set to measure Current (in the range of tens of Amperes), connect the multi-meter in line between the neg battery terminal and the recently removed neg battery cable terminal (make sure that the contacts are solid and don't accidentally ground on the chassis)
3) does the multi-meter measure a current? If so, what is that value?
4) if multi-meter is reading a current greater than ~25mA, go to the fuse panel (multi-meter is still in series) in the vehicle cabin and pull each fuse one at a time individually, and with each fuse out, go back and see if the current reading at the multi-meter has gone back down to 0. If so, then the circuit for which that fuse is removed is the culprit...and can further troubleshoot the wires/switches/components/grounds in that circuit to find the 'leak'...

I thinks the drain is a significant one, possibly a high current short.
I have one multimeter that has a 20A max current feature and I think the fuse blew.
I don't know for sure if it blew right at that moment but I think so. I started then att and charged it up and a couple hours later it died. It is a new battery but im sure ive damaged it.
Whe i removed the fuse from my custom circuit, the drain stopped. I think its a 30 amp fuse so we know thats the limit most likely.
Anyway, my circuit adds power to accessory outlets, power windows, powe locks and a few others.
My belief is that one of the relays i added is stuck on or some wiring is loose, or something is causing a draw. Maybe one of the power lock actuators is stuck on. That would cause a significant draw on the circuit.
But the fact that the batt light stays on means im feeding power to one of the main power groups.
Unfortunately i dont have the vehicle with me during the week. I have to wait until the weekend.
Overall im sure i was my fault. I just hope i didnt burn anything out like the ecu.

 

[mrt6644]

One morething, Re Autozone batteries warrantied? Im pretty sure my newish autozone batt has been damaged by being killed 100%. I suppose it would be dishonest to bring it back and ask for a replacement.

 

[Slow Left]

I thinks the drain is a significant one, possibly a high current short.
I have one multimeter that has a 20A max current feature and I think the fuse blew.
I don't know for sure if it blew right at that moment but I think so. I started then att and charged it up and a couple hours later it died. It is a new battery but im sure ive damaged it.
Whe i removed the fuse from my custom circuit, the drain stopped. I think its a 30 amp fuse so we know thats the limit most likely.
Anyway, my circuit adds power to accessory outlets, power windows, powe locks and a few others.
My belief is that one of the relays i added is stuck on or some wiring is loose, or something is causing a draw. Maybe one of the power lock actuators is stuck on. That would cause a significant draw on the circuit.
But the fact that the batt light stays on means im feeding power to one of the main power groups.
Unfortunately i dont have the vehicle with me during the week. I have to wait until the weekend.
Overall im sure i was my fault. I just hope i didnt burn anything out like the ecu.

Hmmm...given that info, it sounds like this 'custom' circuit is probably indeed the culprit...

In that case, given that you have already tried troubleshooting with the battery installed and that led to possible damage to the battery, I'd roll up my sleeves and trouble shoot that 'custom' circuit with the battery disconnected...using Resistance/Continuity measurements...at least for the wires/grounds...the switches/relays might need some external power (therefore Voltage measurements) to make sure they are opening/closing correctly without 'leaking'...

EDIT: Thinking along the lines of a 9 Volt battery...

You should be able to pull the ECU and run Resistance/Continuity tests on the bread board circuits themselves...just gonna take a bit of intuitive understanding in interpreting the FSM...but basically, the ECU controls the grounding of certain devices

 

[Slow Left]

One morething, Re Autozone batteries warrantied? Im pretty sure my newish autozone batt has been damaged by being killed 100%. I suppose it would be dishonest to bring it back and ask for a replacement.

If it is under warranty, I don't see how returning it would lead to a moral dilemma?

 

[mrt6644]

If it is under warranty, I don't see how returning it would lead to a moral dilemma?

Well, the favt that through my actions, i damaged the battery. Whereas the warranty is probably for manufacturing defects.

 

[Slow Left]

Well, the favt that through my actions, i damaged the battery. Whereas the warranty is probably for manufacturing defects.

Well, you could explain to the folks at AutoZone your understanding of the situation and see if they would still be willing to warranty the battery. This way, in as much as it is important to you as an individual to take on your responsibility, you are giving them, the corporation, the opportunity to show their loyalty...