My immobilizer fix (1 Viewer)

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Lost me on +ve and -ve, sorry.

Battery is 12.53
B is 12.53
E is 12.53 (with fuse in)
C (sorry, i said D above, just noticed. I meant C) is 11.53 with ignition to ON
 
  • Between +ve and -ve of the battery terminals? 12.45
  • Between E and -ve battery terminal? 12.45

Short terminals E and F (with fuse in), will it start?

Put the factory relay back, will it start? If not, what is the voltage at E now?

Keep in mind that this could be an intermittent problem and voltages could change at any time.
 
I ended up rigging the same bypass but using the original relay. Worked like a charm. I was doing something and heard/felt the relay click and realized that the 11.5v was enough. I then rigged an inline fuse (same fuse type as the box) and put it all together and its working great. Thank you very much for the help and working through my confusion.

fuse.jpg
 
Pretty sure I posted the exact fix 2 years ago even made about 8 of them and sent em out for free to those who asked ( all the parts i had) the relay is a $2 part off ebay but it is common to your aux. light light relay most of you use... also the same relay for the tilt trim for my outboard (which is why i had one with me) I build my first one in a parking garage where my wifes lx470 was stuck built with parts and wire in the bottom of my tool bag... yours is much cleaner than my first one...

I would stay away from those $2 relay. I doubt it has voltage spike suppression mechanism in it.
 
it's a simple mechanical relay it's either energized and ON or it is not same thing in one form or another that is in millions of devices without any type voltage spike suppression.... I have at least 4-5 types in my truck at anytime for hvac to elevator to lighting repair... it's just a switch
in this application you just want it to handle the draw that is imposed on it... and 20 amps that most of these simple relays are is overkill
 
it's a simple mechanical relay it's either energized and ON or it is not same thing in one form or another that is in millions of devices without any type voltage spike suppression.... I have at least 4-5 types in my truck at anytime for hvac to elevator to lighting repair... it's just a switch
in this application you just want it to handle the draw that is imposed on it... and 20 amps that most of these simple relays are is overkill

It is more than just a switch. It is capable of generating a few hundred volts of voltage spike when it is turned off. Without suppression, this spike gets to pin #10 of the ECM. Sending a few hundred volts to ECM doesn't sound like a good idea. I will say that I have no problem using a relay with no suppression for lights, and I am not willing to risk my ECM to save a few dollars.

 
I'm not doubting you... exactly but where exactly are these "few hundred volts" coming from? and where would they go? once the switch/relay is de energized everything that you claim could be damaged is removed from the loop... most damage to components is due to heat very rare that millisecond spikes cause component breakdown
Power for a restive circuit is: P = V * I damage is caused by resistor dissipating more power than it is rated for, through heat.
nothing wrong with putting in safe guards but claiming you will fry your ecm is being a little alarmist you could arc fault every circuit in every electrical device if you wanted.....
 
Interesting conversation here. Voltage spikes can occur when a starter solenoid is de-energized. Diodes and fuseable links are used for circuit protection in other applications that I have encountered. Are there any of these in the harness from the fuse box to the starter?
 
I'm not doubting you... exactly but where exactly are these "few hundred volts" coming from? and where would they go? once the switch/relay is de energized everything that you claim could be damaged is removed from the loop...

My Toyota EWD doesn't support your claim. If you are referring to the high power side, then you are in the wrong thread.

most damage to components is due to heat very rare that millisecond spikes cause component breakdown Power for a restive circuit is: P = V * I damage is caused by resistor dissipating more power than it is rated for, through heat. nothing wrong with putting in safe guards but

ECM is not a pure resistive module. It has semiconductor components in it. Voltage spike damage to semiconductor is not unheard of.

claiming you will fry your ecm is being a little alarmist you could arc fault every circuit in every electrical device if you wanted.....

You may want to reread my post again, I said "could".
 
This is awesome. Thank you seriously. I had this happen today and was out cursing at that damn thing at 6:45 this morning.

I'm going to try and do that tonight.
 
I ended up rigging the same bypass but using the original relay. Worked like a charm. I was doing something and heard/felt the relay click and realized that the 11.5v was enough. I then rigged an inline fuse (same fuse type as the box) and put it all together and its working great. Thank you very much for the help and working through my confusion.

fuse.jpg
What type of connector did you use in the original fuse location? Is it just a spade stuck into the original fuse recepticles? If so, I would think you can get the same issue occuring again at that location?
 
What type of connector did you use in the original fuse location? Is it just a spade stuck into the original fuse recepticles? If so, I would think you can get the same issue occuring again at that location?

I checked the fuse receptacle on the power side when I did my bypass, the connection was good and I have zero problem so far. You can run that wire to battery positive terminal if that is a concern.
 
I checked the fuse receptacle on the power side when I did my bypass, the connection was good and I have zero problem so far. You can run that wire to battery positive terminal if that is a concern.

FYI. I ran power directly from the battery to that side of the fuse and the car starts fine but, you get a CEL ECM fault code.

I cleared it a few times and it came back right away. I put the fuse back in and the relay and the code went away.

I think the ECM powers that pole somehow and it doesn't like when it gets power directly from the battery.

I am going to disassemble the fuse box and get to that post inside and run an external fuse there.

In my case at least part of the issue is the female of the fuse holder not making good contact because it is unsupported somehow.
 
FYI. I ran power directly from the battery to that side of the fuse and the car starts fine but, you get a CEL ECM fault code.

I cleared it a few times and it came back right away. I put the fuse back in and the relay and the code went away.

That is not what I meant. I meant instead of powering the bypass kit with power from fuse receptacle, you can power the bypass kit straight from the battery.
 
Thats what I did. Instead of powering it from the 12V fuse location, I ran it straight to the battery. I got a persistent ECM OBD CEL code doing that. When reverting back to original ( my fuse still worked intermittently), the CEL went away.

I just removed the fuse box (grrrrr), and am going to take it apart and hardwire a new fuse receptical into the EFI location
 
What type of connector did you use in the original fuse location? Is it just a spade stuck into the original fuse recepticles? If so, I would think you can get the same issue occuring again at that location?

I used a regular spade connector and initially did have problems. I took it out and bent it slightly so it went it much tighter. I did the same with a few other connections and haven't had a problem since.

EDIT:
All of this is temporary fix until I finally shell out for a new fuse box. I figure if I can mess with it over time and always have that emergency wire to get started (even the wife knows how to use it), then this buys me time and extends my wallet.
 

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