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> need help diagnosing a no-start, electrical problem
post Apr 18, 2009 - 2:33 PM
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6strngs



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So, the other day I went out to start my car, and it was cranking, but not starting. I turned it off, then tried again and nothing happened at all, no clicks, nothing. So I took my dad's car to work, but then when I got home, I tried again and noticed that when you turn the key just to the on position, nothing turns on like the clock, radio, any dash lights (CEL, SRS, etc) except the door ajar light. so I start checking fuses, notice that my 30A fuse for "AM2" is blown. I replace it with a spare, and get back in. turn the key just to the on, and everything is fine, the lights turn on and everything. then I go to crank and it turns over once and then nothing, it blew the fuse again. So basically my car is blowing the AM2 fuse everytime I turn the key to crank. I'm looking at the wiring diagrams but I'm not very good at diagnosing electrical problems. So any help appreciated on places to look for shorts.


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94 GT - Sold -------- 69 Pontiac Lemans - Sold
88 Alltrac - Sold ---- 04 WRX - Sold
00 GT-S - Sold ------ 91 Miata - project/drift car
95 GT - Sold -------- 96 GT - New Daily Drive
post Apr 25, 2009 - 11:20 PM
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johnnypopper420

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so heres what i would say to start with. the am2 fuse is in the starter circuit. there is a black wire with a red tracer that runs from shortly after the fuse to a junction block(left kick panel). check that wire for short to ground. if there is none in that wire then it could be a short going to the ignition switch. that wire is the main power wire for your ignition. anything other than doing a visual inspection will require a voltmeter and doing voltage drops of wires... if you need any other info on where to look or what to volt drop just pm me and i should be able to help you...


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"on the first day, god created fuel injection. on the second day, he created DOHC. on the third day, he created the dual friction clutch. on the fourth day, he created the LSD. on the fifth day, he created the turbo. on the SIXTH day he made a car so amazing, it deserved nothing less than these. and on the seventh day, he drove the HELL outa his 6GC."
-Ryan
post Apr 26, 2009 - 2:15 AM
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6strngs



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Well at least somebody made an effort to help. lol. yeah, basically I seriously spent over 7 hours pouring over the wiring diagrams and testing thing before finally narrowing it down. I know for sure that it's coming from the black w/ orange stripe wire which runs from the fuse box, up to the ignition coil and igniter, and then on to the fuel injectors. where exactly in that stretch of wire harness the short is I'm unsure. I tried jiggling the harness in places with no luck. I think I'm just gonna go ahead and replace the whole harness with my spare one.


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94 GT - Sold -------- 69 Pontiac Lemans - Sold
88 Alltrac - Sold ---- 04 WRX - Sold
00 GT-S - Sold ------ 91 Miata - project/drift car
95 GT - Sold -------- 96 GT - New Daily Drive
post Apr 26, 2009 - 4:29 PM
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Ryouxrs



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if u can keep that fuse from blowing while giving it voltage, just back probe the wire with a test light every so often, and when it no longer lights up, u found your short somewere inbetween the place u just probed, and the last probe point


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Lift Addict!! ^_^
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post Apr 27, 2009 - 1:33 AM
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6strngs



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What I was doing was plugging the test light in place of the fuse. then going along the wire in the diagrams and unplugging connectors or fuses to see which connector along the line causes the light to stay on and find the one before it which causes it to go out... so that the short is somewhere between those two points.

anyway, I pulled my wiring harness out today. didn't take a good look at it, but I did notice that one of the wires going to one of my fuel injectors was actually pinched beneath my valve cover from the last time I had the valve cover off. if, over time, the insulation had melted due to heat and exposed the wire to the head, it would cause it to short. I'm not positive that's what it was, but it's likely.


--------------------

94 GT - Sold -------- 69 Pontiac Lemans - Sold
88 Alltrac - Sold ---- 04 WRX - Sold
00 GT-S - Sold ------ 91 Miata - project/drift car
95 GT - Sold -------- 96 GT - New Daily Drive
post Apr 27, 2009 - 1:35 AM
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Ryouxrs



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that sounds like u found your problem to me


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Lift Addict!! ^_^
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post Apr 27, 2009 - 8:20 PM
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6strngs



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well, I didn't take a good look at it, but it didn't look like it was all the way through the insulation of the wire itseld, just the wire cover. I'll take a better look at it when I have some time to.


--------------------

94 GT - Sold -------- 69 Pontiac Lemans - Sold
88 Alltrac - Sold ---- 04 WRX - Sold
00 GT-S - Sold ------ 91 Miata - project/drift car
95 GT - Sold -------- 96 GT - New Daily Drive
post Apr 28, 2009 - 6:17 PM
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alltracman78



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That's definitely a possibility, AM2 feeds the power to your injectors.

If that isn't it and you have an automatic, take a look at your N start switch.

However, it sounds like something to do with the starter circuit, if it didn't blow until you went to start the car, so focus on that.

To keep the fuse from blowing you can install a lightbulb with 2 spade connectors in place of the fuse.
This will allow you to keep the circuit active while you look at it.


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