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Electrical (logical) troubleshooting so far
ACG S fuse (under hood/engine fuse box) is blowing… various posts indicate alternator, fuel pump, main switch relay… etc
Most posts indicate a short to ground in one of these areas… connections/wiring.
I have learned that there are various checks (sounds, etc) to pay attn to when turning key to diff positions
One area is the main switch relay that provides various clicks… I can actually reach up under dash/console with left hand and put fingers on main relay switch.
With turn to On… relay clicks (and fuel pump should actuate (sound)
With turn to Start… engine should turnover
With turn (back) to On… relay clicks
I have done following… with good ACG S and Fuel pump(inside electrical box - driver side) fuses
Disconnected fuel pump electrical connection
Turn key to On… main relay clicks… (no fuel pump sound [actually wasn't before disconnect either])
Turn key to Start… engine turns, but does not start (shouldn't anyway without fuel)
Turn key to back to On… relay clicks
Turn key to off
Turn key to On… no main relay click
Check ACG S fuse < blown
If I replace ACG S fuse and pull the Fuel pump fuse
Turn key to On… no main relay click
Turn key to Start… engine turns over - no start(shouldn’t w/o fuel)
Turn key to On… ? Cannot remember if click or not.
So, seems issue is between Fuel pump fuse and fuel pump connection.
Anyone have the diagrams for this circuitry and/or any further suggestions/guidance.
I already bought from salvage a fuel pump assembly and alternator… but before swapping am still suspicious of wiring/connections.
thanks for responding.
ok so initial check would be put a multimeter between wire that connects to pin#4 and the associated wire at fuel pump connector... of course with an extension wire to close the gap (from under dash to trunk).
but lets say that there is a short... what is the actual pathway of the wiring from pin#4 to fuel pump? i presume this is not a straight run along the door frame (from pcm to fuelpump). maybe so, but i figured that if ACG was blowing... wiring may be running/connecting with/via other circuits under hood. one of reasons i was looking for diagrams of wiring... though they are not a true map, they give an idea of where connections are going and maybe even wire colors.
I wasn't able to find the electrical schematic you ask for.
To me you need to check "The wire" for a short from the fuel pump side to ground or maybe a short to the other wires going to the fuel pump (on the same connector that plugs into the fuel pump).
However, I can't recommend that bc you don't have a wiring schematic and can fry something if it does run through a computer module.
The safe thing to do is to plug in your new parts one at a time and see what happens.
this is great. i will investigate tomorrow to see if i can find the issue along the specified pathway.
i really appreciate you digging up and sharing these diags. i actually spent a couple hours online during the day searching and learning a lot about the circuits and testing methods.
but this info will make it much easier.
finally had chance to test this after getting some wire to run from under dash fuse slot to fuel pump connector. line tested good for continuity. so i have a salvaged fuel pump assembly and figured i would connect it and see whats up. not sure if good/bad idea as it is not submerged in fuel tank (how can it be different than an empty tank?)
well turning the key to on (relay clicks) and brief buzz from fuel pump
turn key back to off
turn key back to On - no relay click, no fuel pump buzz
checked and ACG fuse is blown
at this point i wonder if the fuel pump (itself, not assembly) is bad... buzz may have come from the fuel level check device
will try to test the salvaged (fuel pump alone) one to see if it will react with power
then get a new one from auto store
hopefully it isnt something else in circuit causing the acg to blow.
I do wonder though, given the buzz when connecting the salvaged assembly
also, thanks for other diagram
Disconnect the fuel pump and PGM FI relay connector. Then check for a short to ground by checking continuity between the BLK/YEL wire and body (ground).
If you have continuity between the wire and ground with both components disconnected, then that's the short and why the fuse is blowing.
guess it took me a bit of thinkin, but i finally got it (your instruction, goin back to your second reply. so i isolated and checked continuity for short to ground on each of the segments. all were OL(no cont) for ohms on multimeter.
i checked
wire (blk/yel) from drvside fuse panel connector to fuel pump
wire (blk/yel) from pfm connector to drvside fuse panel
wire (wht/grn) from pfm connector from underhood fuse box (ACG S fuse)
ACG S fuse socket lt side OL (must be wire to pfm)
ACG S fuse socket rt side 13ohm (11.9volts) must be wire to power/battery
so could it still just be a bad fuel pump (or two) that would cause the ACG S fuse blowing?
i have a jumper battery... can i put this on my salvage fuel assembly (outside of auto) and see if the fuel pump runs or not? not sure if fuel pump runs on 12v or less.
i have a jumper battery... can i put this on my salvage fuel assembly (outside of auto) and see if the fuel pump runs or not? not sure if fuel pump runs on 12v or less.
Yes and yes, 12v and you can test the fuel pump outside the vehicle. Just keep it short so you don't burn out the motor.
Since you've determined that the fuel pump wire is good then you should test the use fuel pump outside the vehicle to see if the fuse blows or not.
My understanding is that the fuse will blow with the fuel pump connected. And not blow if the fuel pump is disconnected. If that's correct then it's highly probable that it's a defective fuel pump.
ok, will test the fuel pump.
find it a little odd that the fuel pump fuse (drv side fuse box) does not blow yet down stream ACG S fuse (underhood box) blows. i suppose exaggerated effects after passing (not) through pfm onto underhood box (acgs fuse).
fuse no 1 on driver side... seems to be E on latest diagram you attached, but where it intersects with second to last diagram you attached is a little confusing. referring to diagrams with focus on driver underdash fuse box.
before your latest diagram attachment, we were looking at previous where blk/yel is at connector A which doesn't seem to line up with fuel pump fuse (E), but could be other wiring/connector interfaces on underdash panel.
while we are still looking a b/y < fuel pump, the b/y in 2nd diagram(post16) shows connector A runs to fuel pump, then b/y jumps from conn A to conn O. then from conn O is red/wht wire (power?) up to fuse E (fuelpump) and on to power other circuits (A, B, C, D).
i stated before that ACG fuse does not blow when i remove the fuel pump fuse(E - drv side box). could issue be on other circuits after/before E... or is E end of line or its own branch?
i did try powering the salvaged fuel pump with jumper battery - after getting connections to stick and a few taps to pump, it did power and spew out a few ounces of fuel. i could NOT get the gauge to respond to power... though very first time (noted above) i conn this salv fpump... i did hear gauge (at least thats what i thought) when turning the key. does gauge require submersion to close circuit or should it work outside of tank.
tomorrow i will go thru and pull each of above fuses and note response.
i learned about and how to check gauge. ohm meter readout changed as i moved sending unit arm... so it appears functional at least at its connectors. could this part of circuit cause a fuse to blow if there was a problem with wiring or is fuse on the circuit to the fuel pump only?
while we are still looking a b/y < fuel pump, the b/y in 2nd diagram(post16) shows connector A runs to fuel pump, then b/y jumps from conn A to conn O. then from conn O is red/wht wire (power?) up to fuse E (fuelpump) and on to power other circuits (A, B, C, D).
i stated before that ACG fuse does not blow when i remove the fuel pump fuse(E - drv side box). could issue be on other circuits after/before E... or is E end of line or its own branch?
i did try powering the salvaged fuel pump with jumper battery - after getting connections to stick and a few taps to pump, it did power and spew out a few ounces of fuel. i could NOT get the gauge to respond to power... though very first time (noted above) i conn this salv fpump... i did hear gauge (at least thats what i thought) when turning the key. does gauge require submersion to close circuit or should it work outside of tank.
tomorrow i will go thru and pull each of above fuses and note response.
Crap! We got our wires crossed.
"i stated before that ACG fuse does not blow when i remove the fuel pump fuse(E - drv side box)."
The "E fuse" is not the fuel pump fuse. The E fuse is the fuel pump relay fuse. So all this time I'm thinking fuel pump fuse is the fuse thats blowing but, you mint the fuel relay fuse (PGM FI). In other words when you say "Fuel Pump fuse" you are actually talking about the PGM FI fuse.
So I've been telling you to look at the wrong side of the circuit. The PGM FI relay has two sides. A power side (fuel pump) and a Ignition side (trigger side).
Will need to start over from squared one.
Just to be sure is fuse A the fuse that blows? And fuse A and E are on the same circuit but the fuse A blows and not E? Even though they are adjacent to each other?
only the ACG S fuse has blown. only time it does not blow is when the fuel pump relay 15A fuse (post15 left diag) is pulled from drv side fuse box.
i wonder(ed) about the pgm-f1 as there is lots o bad press about circuit board given age and heat effects. but throughout testing it has performed as expected with clicks (until acg s blows).
probably worth pulling pgm-f1 out and having a look at board.
pulled pgm-f1 relay and did continuity tests... it checked out ok. also no visual sight of solder cracking. so back to checking the other fuses/relays coming out of there just incase another could be the weak link causing ACG S fuse to blow.
also may still need to spend time on fuel pump circuit. have seen some where connector tests ok for cont, but may not make a good connection through to pump. still this could have a bad pump. but i will test that with jumper battery as well.
i hear you... cant agree more. and Thank you very much for hanging in and providing me lots of info. your last post will be very helpful.
my latest efforts were to check fuel pump in auto using jumper battery. applying voltage, i could hear pump running.
i noticed something else that is a little concerning... no check engine light during key turn to on. troubleshooting suggests could be a ground issue with ecm/pcm. not sure if this could be causing acg s blowing.
i am going back to confirm CEL indicator, then check for shorts to ground on ecm, and also through PGM troubleshooting you posted(#27).
i tried bypassing the PGM-F1 relay (jumping connector terminals: battery, fuelpump and PCM). still could not hear the fuel pump from font seat. direct connect yesterday with jumper battery was just audible close up (above the pump). PGM-F1 Bypass, still may indicate a fuel pump issue. maybe i need to just swap in new pump and see.
also, stepped through pgm-f1 relay circuit troubleshooting... i began with good fuses, therefore step4 took me to step6 (bypassing step5 - ACG S chk). step13 is continuity check between pgm-f1 and pcm... fails. so i am trying to trace... i am wondering if it goes through a connector on drivers side fuse box (module).
the pcm connector and diagram appear off (diagram middle row may have numbers reversed).
so possible that PGM-F1 fuel side is not problem at all, if PCM interface is not working. just not sure why this would cause ACG-S to blow unless there is an effect after the initial PGM-F2 click and open to PCM causes error back through to ACG-S.
Need to see if i can jump(replace) the pgm-f1 - pcm (grn/yel) wire and test (or move to next step). sigh.
^ I can't follow what you're saying. You're over thinking and making it way harder than it is.
Maybe I can help. Right now i suspect it could be a defective pgm fi relay or bad fuel pump.
Fuel pump test post #26 tell you how to test that circuit by bypassing both components. So do that test. If fuse does not blow then the wiring/circuit is good. If it's good then just connect fuel pump and turn key to II position (what ever is listed in test) with the jumper wire connected in place of pgm fi relay. If fuse don't blow the fuel pump is good. Next put pgm fi relay back in place of the jumper wire. Now turn ignition on again and see if fuse blows or not (the fuse should blow during one of the replacement part test).
If fuse doesn't blow bc the starter was never cranked then the problem is in the starting circuit not fuel pump circuit.
did fuel pump test in p#26. battery voltage is avail between connector pin5 and ground in car trunk. checked continuity from connector pin4(neg/grd) and:
- car frame ground - yes cont
- FPump cap(grd) - yes cont
- FPump pin4 - OL
suggestion is to replace fuel pump.
stepped through pgm-f1 relay circuit troubleshooting... made it to step#13 - continuity check between pgm-f1 and pcm... fails. so i tried to trace... it is bundled and goes over to driverside underdash. not sure yet if it goes directly to pgm-f1 or through a connector on drivers side fuse box (module).
this will be harder to bypass(repair)... guess i need a wire with proper pin adapters for connectors... as is suggested in step#13.
thanks for the addtl diags. in your post#38 note C402... in the table comments it refs wire harness A on page 22-52. i would really like to see the fuse connector box layout. not so much the fuses but the connectors. this 'box' has connectors/relays/fuses on front and back side.
here a pic of left and right if facing front of car.
11-25-2015, 05:29 PM
