FJ80 Major Help!

Joined
Jan 15, 2017
Messages
39
Location
Greensboro NC
you really need to go back to the basics here and figure out what component you're missing whether it be spark, fuel, air, or compression. just checking random things with no real direction is going to get you nowhere. neither is just throwing parts at it... unless you get lucky which is rare.
 
Joined
Dec 8, 2006
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New Jersey
 
 
you really need to go back to the basics here and figure out what component you're missing whether it be spark, fuel, air, or compression. just checking random things with no real direction is going to get you nowhere. neither is just throwing parts at it... unless you get lucky which is rare.
The CEL does not illuminate with the key in the ON position indicating that the ECU is not in a ready state. There will be no spark. Without the CEL illuminated this engine will not run.
The fusible link is a known wear item and should be replaced periodically as they tend to go intermittent before failure. It is the most logical place to start.
 
Joined
Jan 15, 2017
Messages
39
Location
Greensboro NC
The CEL does not illuminate with the key in the ON position indicating that the ECU is not in a ready state. There will be no spark. Without the CEL illuminated this engine will not run.
The fusible link is a known wear item and should be replaced periodically as they tend to go intermittent before failure. It is the most logical place to start.
yeah but whose to say the bulb isn't just burned out? my CEL didn't work when i bought my 91 and still ran. second time it happened i needed and ecu lol
 
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yeah but whose to say the bulb isn't just burned out? my CEL didn't work when i bought my 91 and still ran. second time it happened i needed and ecu lol
Always a possibility the bulb is out. If you jump TE1 to E1 (pin 6 to 3) on the diagnostic connector, that should verify the bulb unless the ECU isn't getting +12. In which case we're back to square 1.
 
Joined
Jan 15, 2017
Messages
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Location
Greensboro NC
Always a possibility the bulb is out. If you jump TE1 to E1 (pin 6 to 3) on the diagnostic connector, that should verify the bulb unless the ECU isn't getting +12. In which case we're back to square 1.
correct

this way we can at least know that he’s Chasing the right culprit. but if the cel doesn't flash id replace the bulb and try again to be sure.
 
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Joined
Aug 10, 2011
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Lawrenceville GA
 
my 94 CEL doesn't light and I replaced the bulb, never figured out why but always starts. this could be one of those situations... just my .02
 
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my 94 CEL doesn't light and I replaced the bulb, never figured out why but always starts. this could be one of those situations... just my .02
Again, you are the exception, not the rule.
If the bulb is good, then there is an issue with the logic that fires the bulb. It receives +12 with the ignition on and the ECU grounds the pin to illuminate it. I don't have the schematics for a 1994, but it will be obvious.

EDIT: On the 1991 and the 1996 80s, the CEL receives +12 from the 10 amp GAUGE fuse.
On the 1991 ECU connector E6 pin 8 will go logic low to illuminate the bulb.
On the 1996 ECU connector E7 pin 4 will go logic low to illuminate the bulb.
I can't be sure on the 1994, but the concept is identical.
 
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Joined
Jul 12, 2020
Messages
32
Location
oc, california
Thank you all for the help!!! Found the problem, but the key information is here is to learn to take these steps and diagnose the entire car as @jonheld has stated.. it’ll help you make sure your not just throwing parts at the vehicle..


Well the solution to my problem was the fuel pump!


However I just bought this vehicle and am happy that I changed the fusable link, battery and alternator and still having the low voltage issue .. example: If I lower three windows at once power Drops and light dim.. but that’s another thing..

It always helps to get in your engine bay and learn it like the back of your hand if your ever out on a trail and run into a bind without internet.. it’s good to know what your doing!

Thank you everyone who helped out and it brings me joy to know the MUD community is this resourceful 🏆
 
Joined
Sep 11, 2019
Messages
259
Location
Utah Valley
Thank you all for the help!!! Found the problem, but the key information is here is to learn to take these steps and diagnose the entire car as @jonheld has stated.. it’ll help you make sure your not just throwing parts at the vehicle..


Well the solution to my problem was the fuel pump!


However I just bought this vehicle and am happy that I changed the fusable link, battery and alternator and still having the low voltage issue .. example: If I lower three windows at once power Drops and light dim.. but that’s another thing..

It always helps to get in your engine bay and learn it like the back of your hand if your ever out on a trail and run into a bind without internet.. it’s good to know what your doing!

Thank you everyone who helped out and it brings me joy to know the MUD community is this resourceful 🏆
Congrats, dude! FWIW, the steps you were given here/followed were helpful to me the past few days in diagnosing my truck.
 
Joined
Jul 12, 2020
Messages
32
Location
oc, california
Congrats, dude! FWIW, the steps you were given here/followed were helpful to me the past few days in diagnosing my truck.
Yeah any good mechanic knows it take time and patience no matter how good you are ! These steps will put you thru a professional thought process to finding the solution with the cruiser!
 
Joined
Nov 9, 2012
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9,356
Location
Olathe, KS, USA
 
Yeah any good mechanic knows it take time and patience no matter how good you are ! These steps will put you thru a professional thought process to finding the solution with the cruiser!
Congratulations on your achievement!

Once you had someone to assist you in a logical, patterned process forward, it makes a HUGE difference.

Sometimes it helps to have someone walk you through every step.

Nice job again, @jonheld !
 
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