fix for immobilizer issue? (2 Viewers)

[Jimthom]

I have had this problem exactly twice in 3 years. Both time within a week of each other 6 months ago. Truck started after a 5-10 min rest. And no problems before or since. Was off road and had to be towed by a jeep until it started.

GFL, you wondered why replacing the fuse box solved the issue. Could it be that it is not the fuse box itself, but reconnecting the plugs, similar to pulling a fuse out and re-inserting it. It cleans the contacts. There are many of these connections is the circuit, with the fuse itself and the EFI relay being two of them. But the connections into the fuse box also may be dirty.
So the box may not need to be replaced, just dis-connected and re-connected, but that is the tough part of the job.
It has also been suggested to do the same with the plugs at the ECU.
I have only pulled my fuse and EFI relay and reconnected them and always wonder when I will get bitten again.

 

[GFL]

Your points are excellent. In my case every time it failed if I cleaned or replaced the EFI fuse it would start and it might be good for a month or maybe only one start. The last time I replaced the fuse, it worked for about a week and failed and this time the fuse was burned out and black on one side. The receiving contacts also were burned and I could not get any electrical conductivity on that side, so... I really had no choice but to replace the fuse block. If I could have figured out some way to to put in an inline fuse I would have done so but decided it best to bite the bullet and replace the entire box. The experiences related on this forum and in at least one other suggest that replacement solves the problem. I wish I could give you a good explanation why the block is the culprit and I must admit I am not 100% sure that there is not some other underlying problem. I have a neighbor who is a Nissan mechanic and he has experienced similar issues with fuse blocks for whatever that is worth. I wish you well and your idea of systematically going through and cleaning fuse and relay contacts sounds good to me.

 

[Bbuckner]

So Gary, one more question comes to mind......what was the condition of the plug that you had to remove on the bottom side of the fuse box that supplied power to the bad fuse socket? And thanks again for showing the way....great job!

 

[Jimthom]

Bbuckner, good question. Since GLK found no conductivity in the fuse box, presumably this is on the positive side of the fuse socket, it must be a failure between that point and the battery. It is either the contacts, somewhere, into the fuse box, as you suggest, or perhaps the actual wiring in the fuse box is faulty or too small or there is a poor connection internally somewhere.
Then the question is has this fault been fixed in the replacement fuse box.
It seems like chasing a moving gremlin around the wiring harness. Is the problem at one point or at many points?
And why does this happen to this circuit only?
Are there surges of higher current that overheat a high resistance point? Does this occur at starting?
I am not trying to be contrary but just trying to figure this out so that we know the root cause is and can then fix it.

 

[Bbuckner]

All good questions. I have a son who is an Electrical Engineer, I'll check with him. I also wonder what condition would burn the socket but not blow the fuse? The first fuse I pulled was the fuse from the factory 2001 vintage... Still intact but showing slight discoloration on one leg. I wish I had noted which leg.

 

[GFL]

So Gary, one more question comes to mind......what was the condition of the plug that you had to remove on the bottom side of the fuse box that supplied power to the bad fuse socket? And thanks again for showing the way....great job!

Everything looked good. Clean, bright metal no signs of heat ...

 

[Xetabur]

Well I guess it's my turn. I was about to leave my house to go back to work and click-nothing. Turned the key again and started just fine. Fml

Edit- I made it back home from work but tried to restart it after a few minutes and again it wouldn't start. I replaced the 20amp fuse with a 30 and it started. Wtf? Should I replace the EFI/ECD relay as well?

 

[96crooser]

Well I guess it's my turn. I was about to leave my house to go back to work and click-nothing. Turned the key again and started just fine. Fml

Edit- I made it back home from work but tried to restart it after a few minutes and again it wouldn't start. I replaced the 20amp fuse with a 30 and it started. Wtf? Should I replace the EFI/ECD relay as well?

No, I did and that didn't help

 

[Xetabur]

^Thanks

Edit-Took the LC to my mechanic (Toyota master mechanic) and of course it starts no problem. He's started it every few hours and took it for a spin and no problems. I told him to try and disable the immobilizer. Anything else he should check?

 

[fengler]

Here is my educated guess, I seem to notice these problems happen when its hot outside. Ive also noticed that if you turn the key to the on position, let it sit while everything powers up, it seems to work. If it doesnt, i tap the relays softly and it always works. My guess is our heat coupled with the a/c rejecting heat into the engine comparment may cause some expanding issues which dont allow a solid contact for the relay, especially if its been heat-soaking. What we used to do in the turbo world, and i may do this here, is place a few washers between the hood and its mounts, this will cause the rear of the hood to be lifted a few mm, which allows fresh air to come up through the bottom and rise out.

 

[Xetabur]

I picked up the LC this afternoon and starts right up. The mechanic couldn't find anything wrong. I plan on camping next weekend and hope I don't have issues.

 

[fengler]

If you do, just tap the relays

 

[96crooser]

Here is my educated guess, I seem to notice these problems happen when its hot outside. Ive also noticed that if you turn the key to the on position, let it sit while everything powers up, it seems to work. If it doesnt, i tap the relays softly and it always works. My guess is our heat coupled with the a/c rejecting heat into the engine comparment may cause some expanding issues which dont allow a solid contact for the relay, especially if its been heat-soaking. What we used to do in the turbo world, and i may do this here, is place a few washers between the hood and its mounts, this will cause the rear of the hood to be lifted a few mm, which allows fresh air to come up through the bottom and rise out.

I've had this happen to my 02 LC on cool mornings after sitting all night

 

[96crooser]

I picked up the LC this afternoon and starts right up. The mechanic couldn't find anything wrong. I plan on camping next weekend and hope I don't have issues.

I went through the same thing with a mechanic. Make some kind of jumper wire to replace the EFI fuse, that is the only thing that hasn't failed me.

 

[Bbuckner]

Just got a reply from my electrical engineer son.....he says it is probably a bad ground that goes to the chassis somewhere. He says that these digital components are looking for an exact voltage or current and if the don't see it it just keeps trying until it is satisfied. He agreed that operating the windows and radio probably sent enough current through that bad ground to make the ground and hence the immobilizer circuit could complete. My next move will be to try to clean every earth ground I can find, then replace the fuse box on the assumption that the socket has been damaged because of the bad ground.

 

[Xetabur]

I forgot to mention earlier that when its hot outside and I open/close my driver side door the power locks try to lock. It does this with or without the key in the ignition.

 

[ToddLC]

I have been struggling with this issue as so many of you have for the past 18 months. The car died on my twice this past week, the second time on Friday night. As of this writing, it has still not started. It is being towed to my mechanic tomorrow and I am expecting for him to be able to finally fix the issue.

I tried to do the jumper that is described in this blog post and it did not work for me at all. I also pulled the ECI (20A) and the fuse is burnt. The mechanic checked all of the fuses about two weeks ago and he said that they all looked new.

Is anybody aware of an incident pertaining to the fuse box where the car was not able to start? I will keep everybody posted.

 

[ponytl]

In my case I was not getting consistent power to the relay that allowed the fuel injection to work... I have no idea if it was an issue with the security system, the ecu, or the relay... what I did was using a simple 20amp relay and finding another source of 12v power that only came on when the key was on to power it ... it gave problems for 2 years before I built this new relay and has been trouble free since...

 

[ToddLC]

I had the vehicle towed to my mechanic and he did indeed confirm that the issue was related to the engine compartment fuse box.

There are two metal connections where each prong of the 20A EFI fuse slides into and grab the fuse so that electrical current can flow. When testing, there was current within each fuse connector in the fuse box. When we tested the current through the fuse, there was nothing. It turns out that the gap between that one of the prongs slides into had increased to the point where current was no longer travelling through the fuse.

We were able to fix the issue by tightening the gap for the negative prong underneath the fuse box. When testing, the car started all 32 times that we turned the engine over.

As a precautionary measure, I am replacing the fuse box as the box itself is in rough condition and I want to ensure that this issue is fixed once and for all. The car has over 200K and I plan on driving it till it dies, then rebuilding it.

I hope that this all makes sense and is helpful to others.

 

[Xetabur]

Thanks for the info. Did you replace the entire fuse box or just the lower portion? Looks like the whole box is $453.