Immobilizer issues

[cathaan]

Hey guys,
I have been fighting the immobilizer bug for a few months now. The last time it failed to start in my office parking lot after a light rain. I let it sit for 2 days, replaced every fuse thats mentioned, and suddenly one day it started right up.
Right now it is in my garage, dead as a doornail....
I get the red blinking indicator near the clock. I have once again changed all the normal fuses from other posts with this issue.
Something new this time is that my OBD reader is now saying that it cant connect to the ECU.
Any clue what it could be?? I'm at my end with this problem and it looks like it may be going to a shop tomorrow..

 

[aedavis]

Jumper the EFI fuse under hood - don't just replace it. I jumpered mine a couple months ago after a bout of problems with it failing to start, and it's been starting fine ever since.

I replaced all the fuses first, including the EFI fuse, and it still flaked out. The jumper is the only thing that 'fixed' it. I will likely replace the fuse box, but I'm waiting to see if it craps out again while jumpered.

 

[cathaan]

I'm sorry but what do you mean by "jumper" it?

 

[duggy]

Do you leave the jumper in there? Care to supply us with a diagram?

 

[cathaan]

Has anyone ever replaced the fuse box by themselves???

 

[aedavis]

I'm sorry but what do you mean by "jumper" it?

I put a spade connector in the fuse box, in place of the EFI fuse. The truck has started every time since.



My symptoms were:

1. Truck would start (most of the time) after sitting overnight.
2. If truck was driven a short distance and then stopped for an hour or so, it wouldn't restart.
3. Problem was worse in warm weather.

My theory is that there is a flaky circuit in the fuse box, and when it opens up, the circuit can't pull enough amperage across the fuse, so it won't power the EFI circuit. That's pretty weak, but that's all I can come up with.

Until it craps out again, I'm not going to replace the $400 fuse box. That will be my next step, or at least I'll take a close look at the internals of the fuse box to see if there are any obvious defects, but most likely a break in the solder path won't be visible.

 

[cathaan]

Well she's at the shop getting a new fuse block.... Here's to hoping that solves the problem

 

[cathaan]

New fuse block is in and its been starting fine for several days.

 

[bullfrg]

I had the very same issues and the first dealer that diagnosed it adjusted the contacts on the EFI fuse, which solved the issue for exactly a week. Took it to a friends shop and he confirmed the amperage dropped at the EFI fuse and I elected to just replace the box instead of dealing with a continuing issue that leaves me stranded. Car seems to be working fine now.