Immobilizer question.....& Fuel Pump

[flintknapper]

Anyone know if an immobilizer issue disables the fuel pump?

Wifey called and said her vehicle '99 LX470 died on her a few miles from the house.

Went and picked her up. Cursory look at engine. Plenty of battery, engine cranks fine but will not fire off.

I have a mechanical fuel gauge installed and it is not showing any pressure at all. Popped the underhood Fuse Box Cover and just quickly looked at the fuses there (but did not pull any). All looked fine.

Dark out....so just called a wrecker. $165.00 later for a 3 mile tow and we are back home. Will look at it in the morning. Besides the fuel pump itself (replaced 3-4 years ago) I am just mulling over what would cause a no fuel situation before digging into it.

Thanks guys,

Flint.

 

[JunkCrzr89]

@medtro ?

 

[medtro]

Immobilizer issue can disable fuel pump. Fuel pump relay is at downstream of EFI relay, feed from the same power source.

Do you have flashing security light with key inserted or while cranking?

 

[flintknapper]

Immobilizer issue can disable fuel pump. Fuel pump relay is at downstream of EFI relay, feed from the same power source.

Do you have flashing security light with key inserted or while cranking?

No. I removed key and it flashes per normal. Then insert key and it goes out immediately, also off when cranking. I cranked the engine for a bit (which should have initiated the fuel pump a bit) but it did not show any pressure on my gauge at all. Which leads me to believe the engine died on her because of fuel starvation.

Now....that could be for any number of reasons. Doesn't really sound immobilizer related to me....but was curious about how it affects the fuel pump IF I find something amiss there.

I replaced the fuel pump about 3-4 years ago with a Denso and have had no issues with it. So I will need to first check fuses and relay in the morning as a starting point it looks like.

Normally, when the vehicle is first shut off....the fuel pressure gauge will show about 35 lbs of pressure for at least 30 minutes. It is currently showing nothing.

 

[medtro]

It doesn't sound like you have immobilizer issue. I have read about a switch that shut off fuel supply. May be that switch is activated accidentally?

 

[flintknapper]

It doesn't sound like you have immobilizer issue. I have read about a switch that shut off fuel supply. May be that switch is activated accidentally?

Inertia switch. Unlikely in this case.

But thank you.

 

[flintknapper]

It doesn't sound like you have immobilizer issue. I have read about a switch that shut off fuel supply. May be that switch is activated accidentally?

Well....now things have changed. Looked at it again this morning (cold here) and the security light NOW does not go off when the key is inserted or when cranking. So will jumper from battery to port 'F' later on and see. You might getting a PM for an immobilizer bypass kit.

 

[2001LC]

@medtro Would it be possible to run fuel pump from tech stream, in case where immobilize shorted (fuse box)? Like @flintknapper appears to be!

 

[flintknapper]

Update:

Made a jumper and ran it from the Battery Positive to the 'F' port on the Fuse Box (EFI relay removed) and the vehicle started right up.

Tested the EFI relay and it checked out OK (per the FSM), though relays can be 'weak' and still pass the FSM test.

So looks like the issue is with my Fuse Box though the top side looks good. Immobilizer Bypass is probably going to be my answer.

 

[flintknapper]

Presumably....I can leave my 'Jumper' in place to start and run the vehicle until my Bypass arrives? Yes/No?

 

[medtro]

Presumably....I can leave my 'Jumper' in place to start and run the vehicle until my Bypass arrives? Yes/No?

It is okay to drive with jumper as long as you understand the risk of no fuse protection. I would disconnect it when the engine is not running because it will drain your battery.

 

[2001LC]

You may want to throw a fuse in the line. I'd not drive in rain either, as best to keep water out of box.

 

[medtro]

@medtro Would it be possible to run fuel pump from tech stream, in case where immobilize shorted (fuse box)? Like @flintknapper appears to be!

I don't know. I doubt the fuel pump can be turned on by Techstream when there is no power at "F". @flintknapper does your EFI relay click when the key is turned to ON position?

 

[flintknapper]

I don't know. I doubt the fuel pump can be turned on by Techstream when there is no power at "F". @flintknapper does your EFI relay click when the key is turned to ON position?

Didn't try it. It did click when energized bench testing.

You have PM also. I need a Bypass kit.

 

[flintknapper]

Want to give a shout out to @medtro for going above and beyond. He got my order (placed late that day) shipped out the same day (priority mail) AND by the Grace of God USPS didn't lose it, send it someplace else or sit on it for a week. In fact, it got here earlier than expected.

But @medtro also communicated with me via Email about some questions I had. Very quick to answer them. First rate service. He even followed the tracking to be sure it was delivered.

Installed the Bypass Kit and the vehicle is up and running fine now. Excellent quality kit and extremely easy to understand instructions...complete with photos.

 

[OwnerCS]

Good job! I carry the medtro kit in my on-vehicle parts stash as insurance.

 

[flintknapper]

Good job! I carry the medtro kit in my on-vehicle parts stash as insurance.

At some point I may pull my under-hood fuse box and repair or replace it, then keep the kit as a workaround. IF you are able to determine/diagnose your issue as immobilizer related (because of the fusebox) then its a good item to have.

To that end....IF your vehicle will crank...but not start (as mine was doing) look to see that the security light on the panel (it's not on the dash) is still blinking when insert your key or while cranking. IF it is....then the kit should/might get you going again. Normally the light will go out immediately if OK.

I was also able to start and run mine by running a jumper wire from Battery + to the 'F' port of the fusebox after removing the EFI relay. So...able to use the vehicle while waiting on the kit to arrive.

 

[flintknapper]

One note after installing the Bypass kit. IF you plan to leave it installed long term....it would be wise to attempt to tuck it under the fuse box lid. Different year models have slightly different arrangements for fuse/relay positions. In my case... there was just barely enough room to push the bypass kit down around the side of the relays.

My kit would not fire the engine because of the 'A' terminal on my EFI fuse slot being the problem. The solution for that is to run a jumper from the kit to the Battery + post. IF you have to do that....then you can cut a small window in the fuse-box lid and housing to accommodate the wire. Be sure to insulate the wire so it doesn't wear through and cause a dead short right off the battery (VERY BAD).

After having done the above....I was able to reinstall the top to my fuse box. I don't think leaving it off and having the fuses/relays exposed is a good thing long term.

 

[flintknapper]

Want to give a shout out to @medtro for going above and beyond. He got my order (placed late that day) shipped out the same day (priority mail) AND by the Grace of God USPS didn't lose it, send it someplace else or sit on it for a week. In fact, it got here earlier than expected.

But @medtro also communicated with me via Email about some questions I had. Very quick to answer them. First rate service. He even followed the tracking to be sure it was delivered.

Installed the Bypass Kit and the vehicle is up and running fine now. Excellent quality kit and extremely easy to understand instructions...complete with photos.

Update: More than 3 years later, everything still working fine. Bypass kit worked great for me.