Kill switch electrical questions

[Topdawg_135]

Originally Posted by echo-francis

i know its not related to this thread but i see you have a exaust insulation, did you see any difference with that?

The exhaust wrap has been on there for about 7 years, long before I got into ecomodding. So unfortunately I don't have any before after MPG numbers.

[darcane]

Originally Posted by Topdawg_135

Thanks. I did not have that wiring schematic in my Chilton manual. Could you possibly post the whole page so I can check where the others go?

I want to make sure that one of those doesn't connect to the immobilizer circuit(which is the problem we have been having all along).

I feel that the one common yellow/black is the same as the one at the fuel relays behind the blower/ecu in the cab, which if I'm correct connect to the immobilizer as well.

Also I'm sorry for the ambiguity in my last post. When I checked it, it appeared that all the wires are connected. Not just the wires to the fuel injectors.

Here's the link again to the complete wiring diagram:
Wiring Diagram

The common yellow/black is for injectors, IAC valve, and CKP and TDC sensors. All of these are on the engine itself, and I would guess that killing the whole lot won't trigger a CEL or the immobilizer. This is the wire I plan to interrupt with my kill switch. Tracking down where it goes would be helpful.

I mostly haven't gotten around to it because I'm replacing the rag top on the wife's Mustang (harder than it looks...) and that's using up all my garage time.

[Topdawg_135]

Thanks everyone. It does look like the common yellow/black is the way to go.

The only concern I have is with the crank position sensor. I know the engine can run with just the crank position sensor or the cam position sensor working, but I think it might put it in limp mode.

[moorecomp]

Ain't gonna be running at all with the power off to the injectors.

[darcane]

Well, now that the Mustang is done, I did a little more wire tracing last night.



Highlighted orange is the yel/blk wires I am trying to follow, highlighted green is the wire I want to interrupt.




In my hand are three relays. The brown one is PGM-FI Main Relay 1, the blue one is PGM-FI Main Relay 2, not sure what the other one is. One yel/blk from each relay goes up and connects with two more yel/blk (this junction is just to the left of the PCM and is wrapped in blue shrink tube). One of those yel/blk goes to the immobilizer (left of the picture) the other is supposed to go to C102. The wire that is supposed to go to C102 is flagged with some electrical tape.

Which brings me to where I am stuck at. The gray, 20-pin connector (looks white in the pic) just right of my wire marked with tape... is this C102? I can only find two yel/blk wires, my marked wire and one that appears to go under the hood (but this one is far more difficult to follow). According to the diagram, there should be two more going to IGP1 and IGP2 on the PCM. I can't find these. The wiring diagram has the caveat of "except GX & HX" and it's possible my HX doesn't have these wires. I'm concerned that if I interrupt my flagged wire, I may also interrupt the IGP1 and IGP2 to the PCM which may trigger a trouble code or something.

Any thoughts?

[kurzer]

the green marked wire feeds the injectors? why dont u cut the red yellow at main relay 1? in my eyes, this will bring down the whole system without trouble and with little current.

[darcane]

Originally Posted by kurzer

the green marked wire feeds the injectors? why dont u cut the red yellow at main relay 1? in my eyes, this will bring down the whole system without trouble and with little current.

The highlighted green wire is for the injectors, crank sensor, TDC sensor, and IAC valve. Kill it and the engine dies, hopefully with no codes generated.

Cutting the red/yellow wire would kill the immobilizer and I would have to key-off/key-on to restart the car.

I'm not sure of the function of the IGP1 and IGP2 at the PCM. If killing this wire to the PCM triggers a trouble code, it could cause problems as well.

[kurzer]

C102 is ground? sure?? and the fuses are ground too?

did u test the relais 1 and and the immo issue? maybe by pullig the relais?
what is the key doing, to reset the immo?

[darcane]

Originally Posted by kurzer

C102 is ground? sure?? and the fuses are ground too?

did u test the relais 1 and and the immo issue? maybe by pullig the relais?
what is the key doing, to reset the immo?

Sorry, I was incorrect earlier. The injectors are each controlled by a switched ground; I would be interrupting the common power wire going to them.

C102 is a junction/connector in the harness. There are a large number of wires going to it (at least 13 per the wiring diagram).


I haven't tested killing Relay 1...
But Vman455 did. See post 14 and 15 of this thread. Since it didn't work for him, I didn't bother trying it myself. I haven't delved into precisely how the immobilizer works, I just plan to avoid touching any wires related to it.

[darcane]

Well, I went ahead and did it last night. I snipped the yellow/black wire on the backside of the connector shown in the picture above. I wired up a relay and tested it on the way into work this morning.

Flip it off and the engine cuts out immediately and the MIL comes on. No Immobilizer light on the dash. Flip it back on and I can bump start it right back up any time.

The only unexpected behavior is that my Ultragauge turns off when I flip the switch.