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How To Change Ignition Coils On '92 Ls400


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Hi Guys,

Lextreme used to be a good source for tutorials on the LS. I cannot find them anymore and thought someone on here may know???

I need to check or change out my coil(s) on my '92 LS400. Car is chugging badly, cats glowing red, etc.



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Alrighty then, changed the coil on the driver side and problem fixed...at least no more chugging and glowing cats! Those cats looked like they were out on vacation from hell, indeed!

Anyway, for those who may need to change out the driver side coil on a '92 LS400, the following may be helpful. Also posted parts info on the bottom of this post, for those who need it. Sorry, but I don't have any pictures. One important note: I checked my original coil and the new coil with a digital Ohm meter, but saw no difference in the readings, but maybe the meter was not calibrated low enough. So, for all of you out there with similar symptoms and you have ruled out other issues, do not depend upon the meter readings for the coils!!!

1. Disconnect the battery and remove it completely out of the engine bay. You may need to remove the plastic cover thingys first.

2. Disconnect 3 connections at the coil - the coil is on the drivers side between the left bank of cylinders and the fuse box, about 8 inches down. You can see the high tension wire plugged into it; To disconnect these three connections, you need to carefully press the locking tabs on the sides and gingerly wiggle them off. This is the third hardest part; if you have passed this point, you are almost there;

4. Get a 10mm socket and a 2 inch extension with a ratchet - 1/4 inch drive works well because of the tight space; the coil is mounted on a bracket which is bolted to the engine block in two places - one (10mm bolt) is in front right behind the serpentine belt; reach in put the socket onto the bolt and loosen it counterclockwise. Don't make the mistake of loosening the white plug bolted onto the bracket - it is also a 10mm bolt, but you don't need to take that one off. The correct bolt is a little further back in, and actually bolts onto the block. Not sure what will happen if you drop the bolt, so don't do it!

5. Get a 14mm wrench - a long handled on will be better, since a socket and ratchet won't help you with this one. Because the whole setup is just above the A/C compressor, there is not much room to work here. It it not hard to get out, but you will need to fit the wrench and loosen, repeatedly until it is loose. Again, not sure what will happen if you drop the bolt, so don't. This bolt is suprisingly larger. Now that you have both bolts out, you can take a beer break. I did, this was the second hardest part of the job. Anyway, I digress.

6. Now that you have the coil assembly out, you will see that the bracket is held on with four phillips head bolts. Undo them, clean with your choice of cleaner and bolt the new coil onto the bracket.

7. Install the bracket assembly with the 10mm bolt first - this will make it easier to get the 14mm bolt in, which is a PITA. But I digress. Finger tighten the 10mm bolt to where most of the slack is taken up and the bracket does not flop around. Now comes the hardest part - getting the blankety blank 14mm bolt back in. It may feel like it's impossible to get that bolt back in, but take a good look at the engine boss - for those of you who don't know, its a bit of the block that juts out and serves many purposes in enginese. Anyway, note the angle of the boss, and this will give you an idea of how to hold the bolt while trying to get it started. This is where keeping the bracket somewhat loosey goosey helps out. You may have to work the bracket at bit with your left hand, while trying to get the bolt threaded with your right, but it should only take about 5-7 minutes if you're lucky. Tip - use one finger on the head of the bolt, and the other to try to turn it :lol:

8. Got the 14mm started? Good, you're over the hill! Tighten the 14mm securely (check the manual for torque specs - I did'nt. Just made sure the darn thing was tight enough so it wouldn't pop out from engine vibrations).

9. Tighten the 10mm bolt behind the serpentine belt.

10. Connect the wires to the white plug on the bracket.

11. Connect the power connection plug onto the coil.

12. Connect the high tension wire.

13. Check to make sure all tools are out of the Battery tray, and install the battery with clamp, cover, whatever.

14. Connect the battery + wire first, then negative.

15. Done.

Parts used

New coil from NAPA P/N#IC160; (Original Toyota P/N:19090-50010; this ignition coil is referenced as LH coil in the service manual, so LH is equivalent to the driver's side. This is important if you have to get it from Sewell, since they know coils as #1 or #2 but cannot tell you which is which!); Brake cleaner fluid. Total time to remove and reinstall: about 1 hour (including getting part from NAPA store). Now, I would like to find out what happened to the Lextreme website? Anyone got any ideas?


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  • 8 years later...

I know this is an old thread, but the below additional information may be useful for anyone attempting this task:

(referring to the step numbers above):

1. I found it useful to remove the battery tray, secured by 4 10mm nuts, which provides a bit more room to work.

2&4.  I removed the 10mm bolt holding the white connector to the bracket, so I didn't need to disconnect the white connector - I'm always concerned about trying to get old plastic parts to disconnect & reconnect without breakage.

7. Putting the 14mm bolt back on first was easier - sprayed WD40 on the bolt and the bolthole.  I also dropped the bolt once, and it just ended up in the plastic pan, so it is easy to retrieve.  Getting the 14mm bolt back in place requires good feel, so this is where I took off the gloves.


No skinned knuckles, a successful job and my 91 definitely runs smoother!


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