88 5.0 wiring - NGS switch confusion - Ford Muscle Forums : Ford Muscle Cars Tech Forum
 
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post #1 of 3 (permalink) Old 08-02-2014, 03:19 PM Thread Starter
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88 5.0 wiring - NGS switch confusion

hi there, im a little bit lost with this on my 5.0 swap into my 68 mustang, i got most of it wired up temporarily, but didnt know where the black with white stripe wire should go, that came from the green square connector in the kick panel of the 88 mustang.

when i turned on the ignition, the fuel pump relay energised for a second, then switched off.. giving this black-white wire 12v turns on the fuel pump again

the information here -http://www.rowand.net/Shop/Tech/FordEFISwap.htm

says this wire connects to the ground side of the T5 neutral gear switch.. does this not mean that the fuel pump will turn off whenever the car is in neutral ?
additionally, the haynes wiring diagrams dont show the signal return connected to the NGS at all.

i also have confusing information regarding the red-blue stripe wire, - i suspect though, this is hot in start only and connects to the starter relay, tfi, and the coil for start power only, but no power if the t5 is in gear and clutch is out. so that would also connect to teh ground side of the NGS (i have no clutch switch) ?

so to the + side of the NGS what do i need to use? does that go straight to pin30 on the computer? the haynes shows it going to pin 30 and to the ignition switch, but not whether its run, start or both, or neither.

this still makes me think the fuel pump will turn off whenever i put the car in neutral though, as pin30 has 0 volts in neutral?

cheers.

mark.
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post #2 of 3 (permalink) Old 08-02-2014, 05:48 PM
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Re: 88 5.0 wiring - NGS switch confusion

Quote:
Originally Posted by markw View Post
hi there, im a little bit lost with this on my 5.0 swap into my 68 mustang, i got most of it wired up temporarily, but didnt know where the black with white stripe wire should go, that came from the green square connector in the kick panel of the 88 mustang.
It goes to both the NGS and the clutch switch, then on to pin 30.
Quote:
Originally Posted by markw View Post
when i turned on the ignition, the fuel pump relay energized for a second, then switched off.. giving this black-white wire 12v turns on the fuel pump again
Don't do that. Powering unknown pins for fun is not always safe for electronics. Anyway, ON then OFF without cranking is correct. The ECM powers the fuel pump for a second or two when keyed to ON (not START) in order to prime and pre-pressurize the fuel system. It then stops the fuel pump until it 'sees' ignition trigger pulses (meaning an engine turning and trying to run) and turns the pump on again. As long as the ECM sees trigger events, the pump runs. Turn the key OFF or stall the engine and the trigger signals stop, and so then does the pump.
Quote:
Originally Posted by markw View Post
i also have confusing information regarding the red-blue stripe wire, - i suspect though, this is hot in start only and connects to the starter relay, tfi, and the coil for start power only, but no power if the t5 is in gear and clutch is out. so that would also connect to the ground side of the NGS (i have no clutch switch) ?
Right, it gives a cranking signal to the starter relay (solenoid), and signals other stuff that you're cranking the engine.
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so to the + side of the NGS what do i need to use? does that go straight to pin30 on the computer?
Yep. With an automatic trans, it doesn't care, but with a manual, the ECM must juggle idle speeds differently. So, in order to prevent stalling when you suddenly push teh clutch in or pop out of gear, the ECM sees the 'neutral' condition and compensates with idle air valve and fuel. It is equivalent in function to the dashpot used on carbs.

David

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Last edited by PSIG; 08-02-2014 at 05:57 PM.
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post #3 of 3 (permalink) Old 08-03-2014, 01:40 PM Thread Starter
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Re: 88 5.0 wiring - NGS switch confusion

thanks a million once again, it makes sense now..

giving the b/w wire 12v wasnt completely arbitrary, but it was wrong, i misunderstood the wiring diagrams thinking it would take 12v via the NGS, but .. i was wrong.. and i did fry it. ass.. i re-soldered the cooked trace and it seemed to be ok, gave me the codes (though i seem to have fried the MAP too), and was initially giving me a code 10 interval code, then a code 11 (i think) for system ok.. now i get a code 22 after the interval code.. I dont know why it gives me this and none of the other codes after the interval.. i suspect this means, fix the MAP before it gives a code 11


another thing.. im trying to decide where to link my red-green strip (hot in run only) wire.. wondering whether it matters if it is also active in acc?


cheers,

mark

Last edited by markw; 08-04-2014 at 02:05 AM.
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