1999 UZJ100 Intermittently Drops Dead

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Have you tried a different ecu? I've seen behavior like this with a faulty ecu (bad internal ground causing intermittent/random shutdowns as described). Also check to make sure all ground circuits for the ecu are properly grounded.

3 coil pack failures... check ignition component grounds.

Another thing you can do is to jiggle various harnesses and connectors while the engine is running. This could help isolate any loose/intermittent connections.
 
jwagner said:
-if it happens again try to note the voltage. still cant help but feel like its something simple like an alt connection or alt itself. but the immobilizer system is also a good guess.
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if it were an alternator problem, then the battery would drain down and it wouldn't restart.

this is most likely a ground or relay issue - somewhere - anywhere...
 
You say you replaced the EFI Relay, but did you check the EFI Fuse? There should be a spare on the top of the cover. I had a intermittent start issue and the culprit turned out to be that fuse, which tested fine but couldn't reliably supply the necessary current.
 
bamachem said:
if it were an alternator problem, then the battery would drain down and it wouldn't restart.

this is most likely a ground or relay issue - somewhere - anywhere...
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- the OP had said it was re-started while rolling...
-really curious to see what this turns out to be.
 
lndcruz said:
Don't these trucks have immobilizers? Wonder if its something wrong with the key or immobilizer.

Friends lexus would do this occasionally and it turned out to be the immobilizer in the key.
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I had a different ECM put in the truck. It was used, but Locksmith Charley in Phoenix was able to reflash it and rekey the two old keys we had, as well as a new one. It died on us the other day with the new key.
 
SupraTuRD said:
Have you tried a different ecu? I've seen behavior like this with a faulty ecu (bad internal ground causing intermittent/random shutdowns as described). Also check to make sure all ground circuits for the ecu are properly grounded.

3 coil pack failures... check ignition component grounds.

Another thing you can do is to jiggle various harnesses and connectors while the engine is running. This could help isolate any loose/intermittent connections.
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Yep, changed out the ECM, see the post above. Checked grounds and tried to get it to quit while it was running by moving things around, but no dice. I can't say that this happens when going over bumps...happens on totally smooth road too.
 
bamachem said:
if it were an alternator problem, then the battery would drain down and it wouldn't restart.

this is most likely a ground or relay issue - somewhere - anywhere...
Click to expand...

Ok, for the sake of argument (Auto Mechanics 101 here) let's say the truck is running, and the alternator is suddenly taken out of the picture due to a loose wire or something similar that keeps it from working intermittently for small periods, but otherwise it functions fine. What happens? Does the engine quit?
 
Travis351 said:
You say you replaced the EFI Relay, but did you check the EFI Fuse? There should be a spare on the top of the cover. I had a intermittent start issue and the culprit turned out to be that fuse, which tested fine but couldn't reliably supply the necessary current.
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Interesting...I pulled that fuse, and it was pretty dirty. I thought I had checked the fuses (you'd think the auto electric place I brought it to - twice - would have checked that as well). It had some black carbonized buildup on the contacts. I replaced it, and the truck hasn't died since...crossing my fingers. At this point I don't even care if it only turns out to be a $.60 fuse when I've already replaced half the truck...I just want it to work.
 
truggier said:
Ok, for the sake of argument (Auto Mechanics 101 here) let's say the truck is running, and the alternator is suddenly taken out of the picture due to a loose wire or something similar that keeps it from working intermittently for small periods, but otherwise it functions fine. What happens? Does the engine quit?
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-no, the engine would run off the battery till the batt didnt have enough charge to run the engine. you could at this point still have enough charge to run accessories even w/o the engine running till the battery is completely dead. iirc the difference between a batt that will crank an egnine and one that wont is only like .75v
-my thought was that the alt maybe cutting in/out. this could be a loose connection, or an internal problem with the alt.
-say it dies while driving and the truck compression starts itself with the alt working again...
-i guess to go along with my theroy would be the fact that this may not throw a code because its such a basic system. and it may only show a small difference on the gauge...keep a very close eye on the gauge. especially when it happens.
 
truggier said:
Interesting...I pulled that fuse, and it was pretty dirty. I thought I had checked the fuses (you'd think the auto electric place I brought it to - twice - would have checked that as well). It had some black carbonized buildup on the contacts. I replaced it, and the truck hasn't died since...crossing my fingers. At this point I don't even care if it only turns out to be a $.60 fuse when I've already replaced half the truck...I just want it to work.
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Good luck I hope that works for you. If not I would definitely check out the TPS and APPS
 
truggier said:
Interesting...I pulled that fuse, and it was pretty dirty. I thought I had checked the fuses (you'd think the auto electric place I brought it to - twice - would have checked that as well). It had some black carbonized buildup on the contacts. I replaced it, and the truck hasn't died since...crossing my fingers. At this point I don't even care if it only turns out to be a $.60 fuse when I've already replaced half the truck...I just want it to work.
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That's exactly what my fuse looked like. I thought that the immobilizer system was disabled once the engine was running. Live and learn; I guess I was just lucky that mine only failed when trying to start.

A friend "SouthernSafaris" on here taught me not to trust those mini fuses after 10 years. Sometimes they test OK on the Ohmmeter, but don't really work. When in doubt, swap it out.

Give "Pants" a shout out for his thread in 2007 as that's what saved me. https://forum.ih8mud.com/100-series-cruisers/179908-help-im-irate-ignition-trouble.html

If this actually fixes both starting problems as well as stalling on the road, maybe it's time to put one of these in the FAQ with a more appropriate name. I vote for Intermittent No Start/ Stalling.

Keep us posted Truggier...I am on month 3 with no problems after replacing that fuse.
 
Travis351 said:
That's exactly what my fuse looked like. I thought that the immobilizer system was disabled once the engine was running. Live and learn; I guess I was just lucky that mine only failed when trying to start.

A friend "SouthernSafaris" on here taught me not to trust those mini fuses after 10 years. Sometimes they test OK on the Ohmmeter, but don't really work. When in doubt, swap it out.

Give "Pants" a shout out for his thread in 2007 as that's what saved me. https://forum.ih8mud.com/100-series-cruisers/179908-help-im-irate-ignition-trouble.html

If this actually fixes both starting problems as well as stalling on the road, maybe it's time to put one of these in the FAQ with a more appropriate name. I vote for Intermittent No Start/ Stalling.

Keep us posted Truggier...I am on month 3 with no problems after replacing that fuse.
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Thanks Travis351 and rusty_tlc. I'm happy (actually ecstatic) to report that after replacing the fuse, it hasn't died for a week through some pretty heavy usage. We've had it go longer than this without dying before, but the timing is pretty convincing.
 
Exellent read, this helped me track down a simular problem.

At first I was overthing things, my rig has a trd supercharger and I thought this might be causing the truck to die seconds after starting it.

I thought the MAF would be affected by the supercharger, because if I gave it some throttle it would stay running. If I started it and allowed it to idel (this is after the engine is warm) it would die.

Rob
 
So the one remaining suggestion from this thread was to replace the APPS / TPS. Well, get this: it still hasn't died yet, but last night we started the cruiser, and I notiiced it was idling high (1400 - 1500)...and then the 'check engine' light came on. When I pressed on the accelerator, it had no power - with the accelerator floored, we barely crept along at a few miles an hour, even on a level road. So I turned it off and then restarted it, and everything seemed fine - except the 'check engine' light remained on. We had to make it somewhere, so we just drove it and all worked ok, other than the 'check engine' light staying on.

When I got back home, I put a code reader on it, and this is what I got:

P1121: Accelerator Pedal Position Sensor, Range / Performance Problem

:lol: This is like the only sensor that I haven't replaced. So I guess will be replacing the APPS / TPS soon. What the heck could go wrong after that?

PS my wife drove the cruiser to work today anyway. I hope it doesn't give her problems.
 
NMuzj100 said:
Usually you only need to replace the APPS. The TPS is rarely the problem.


APPS / TPS FAQ
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Thanks...I had seen that reference previously. It's hard to get a consensus on forums - seems like everyone has a different opinion. However, most people would agree with you that only replacing the APPS is necessary.

I talked to Beno at American Toyota today, and he quoted my $224 for a new APPS with the Mud discount. But he said that the problem could be caused by the TPS ($66) and / or the Throttle Control Motor ($220), and since all three are provided with a new throttle body ($850), I could just buy that instead. $224 sounds much better than $850...

Since I'm reading a CEL P1121, I guess I'll just start with the APPS (besides, I don't know how to adjust the TPS). We had the problem again today. The weather has been colder and I hear that this can trigger it.
 
Hi Truggler,
I have a 99 V8 Landcruiser that is experiencing the same problems that you have described.
How did you resolve the problem please?
Peter
 
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