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How is this possible ?! by Lou6t4gto
Started on: 02-26-2014 07:28 PM
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Last post by: hookdonspeed on 02-28-2014 05:55 PM
Lou6t4gto
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Report this Post02-26-2014 07:28 PM Click Here to See the Profile for Lou6t4gtoClick Here to Email Lou6t4gtoSend a Private Message to Lou6t4gtoEdit/Delete MessageReply w/QuoteDirect Link to This Post
this is making me crazy ! according to the GMTUNER chart for wiring a 1998 3800SC to a 87 fiero. there is only 1 wire going from Clear #3 (dark green/white) to the fuel pump Relay pin "A". what happens to all the other wires on that relay ??? the relay can't just be hanging there connected by only 1 wire. I've read and re read the charts, am I "missing" something ?? (besides my mind) HELP !
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hookdonspeed
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Report this Post02-26-2014 07:54 PM Click Here to See the Profile for hookdonspeedClick Here to visit hookdonspeed's HomePageClick Here to Email hookdonspeedSend a Private Message to hookdonspeedEdit/Delete MessageReply w/QuoteDirect Link to This Post
it only needs 1 wire to 'activate' the relay... i cant remember if it grounds or supplies power, but hte other side of the relay goes to either ground or power, then 2 pins will go from battery to the fuel pump (basicly makes a `hot wire` type setup, or you can wire it into the factory harness inside the car for fuelpump power. then the fuelpump will goto ground.

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hookdonspeed
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Report this Post02-26-2014 08:03 PM Click Here to See the Profile for hookdonspeedClick Here to visit hookdonspeed's HomePageClick Here to Email hookdonspeedSend a Private Message to hookdonspeedEdit/Delete MessageReply w/QuoteDirect Link to This Post
here, found this for ya..


image courtesy of hercimer01 in this thread http://www.fiero.nl/forum/F...3/HTML/000130-4.html

i personally recommend making it a *hot* wire setup, run a wire from the battery (fused) to the relay, rather then use the c203 wire. lookup fuelpump hotwire setup.

[This message has been edited by hookdonspeed (edited 02-26-2014).]

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Lou6t4gto
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Report this Post02-26-2014 08:05 PM Click Here to See the Profile for Lou6t4gtoClick Here to Email Lou6t4gtoSend a Private Message to Lou6t4gtoEdit/Delete MessageReply w/QuoteDirect Link to This Post
sorry, I'm just Not "Understanding this". :-( Picture this: new harness, the relay is just "sitting there", wired to" Nothing". so, I connect Clear #3 to pin "A" of the Relay. (don't know if clear #3 is hot or ground). So, there are still 4 wires hanging from the fuel pump relay, only #3 clear is connected. WHY is there no' DIAGRAM" anywhere of where the other wires go. With the newly made 3800SC Harness, is the fuel pump somehow getting it's power from another source other than this relay ? please bear with me on this.
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hookdonspeed
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Report this Post02-26-2014 08:06 PM Click Here to See the Profile for hookdonspeedClick Here to visit hookdonspeed's HomePageClick Here to Email hookdonspeedSend a Private Message to hookdonspeedEdit/Delete MessageReply w/QuoteDirect Link to This Post
think we cross posted, hope that diagram helps.
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Lou6t4gto
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Report this Post02-26-2014 10:43 PM Click Here to See the Profile for Lou6t4gtoClick Here to Email Lou6t4gtoSend a Private Message to Lou6t4gtoEdit/Delete MessageReply w/QuoteDirect Link to This Post
I feel so stupid. I know where 203 "L" is, and 203"B", and 203 "M", but where do I hook "c2-3 FP Relay Control" to ?? boy I hope their are "Letters" on that Relay. I am an idiot when it comes to things like Relays. thanks
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sco77
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Report this Post02-26-2014 11:37 PM Click Here to See the Profile for sco77Click Here to Email sco77Send a Private Message to sco77Edit/Delete MessageReply w/QuoteDirect Link to This Post
You're relay consists of 4 wires, 1 is a ground (blck/85) for the control which you ground anywhere you want, one is a control wire(86) that goes to the PCM fuel relay control, these 2 wires will be a low gauges like 16 or 18+ gauge because they carry no load, their only purpose is to flip the relay switch.. The other 2 wires are your line input from a fused power source (battery) (red/30) and the output to the fuel pump hot (yellow/87)...

Sorry for explaining it this way, you just seem like you are confused on what a relay actual is.

------------------
86 Fiero GT 4spd - L67 swap: VS cam, GenV
98 GTP - Some mods

[This message has been edited by sco77 (edited 02-26-2014).]

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Lou6t4gto
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Report this Post02-27-2014 01:38 AM Click Here to See the Profile for Lou6t4gtoClick Here to Email Lou6t4gtoSend a Private Message to Lou6t4gtoEdit/Delete MessageReply w/QuoteDirect Link to This Post
you got that right ! So the "CONTROL" is a ground ? I have Not got a "Clue" when it comes to what a Relay actually Does or How it does it, same for resisters & Diodes. I can even fix electrical tools or anything else, as long as I" Can SEE how it works".
I can build you a house, rebuild engines, automatic trans and Paint custom paint jobs. But when it comes to electricity (something that I "Cannot SEE How it works"), I'm LOST ! If I don't have a" schematic" to Look at, I'm in trouble. I probably Should buy a BOOK on how Electronics "WORK" ! Thanks
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hookdonspeed
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Report this Post02-27-2014 08:25 AM Click Here to See the Profile for hookdonspeedClick Here to visit hookdonspeed's HomePageClick Here to Email hookdonspeedSend a Private Message to hookdonspeedEdit/Delete MessageReply w/QuoteDirect Link to This Post
a relay is a simple 2 position switch(for standard 5pin relays), NO (normally open) or NC (normally closed) operation. that's 3 of the pins (a lot of time only 2 of the 3 are used, depending on if you want it on or off normally)
the other 2 pins are just simply an electro magnet that operates the switch. apply power to the magnet and it will pull alittle piece inside switching the direction the power goes.

this diagram might help alittle.

(in diagram pins 85 and 86 are the magnet, the other 3 are the switch, you can see the flow would normally go from pin 30 to 87a when the magnet is off, energizing the magnet will make the flow go from pin 30 to 87.)

the fuel pump really sits normally open (no power can get threw), when the ecu gives power to that pin3(c2 connector to the ecu pin 3) fuelpump control wire, it will energize the coil in the really closing the loop, giving power to the fuel pump.
the other end of the coil in the relay simply just gets grounded. (c203 pin M by factory), the "feed" of the fuel pumps power can come from either the c203 pin B(orange/black), or directly from a fused wire off the battery. the other end of the relay wire can either goto c203 pin L(tan/white), or directly to the fuel pump harness against the firewall. doing the direct battery to fuel pump is the "hot wire" setup that many use because it gives a better power source then factory.


hope this help.


resistors just reduce the voltage in a circuit by the value that they are... diodes are simple things that just allow the electricity to flow in 1 direction (so things don't "back feed" etc)

[This message has been edited by hookdonspeed (edited 02-27-2014).]

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Blacktree
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Report this Post02-27-2014 11:08 AM Click Here to See the Profile for BlacktreeClick Here to visit Blacktree's HomePageClick Here to Email BlacktreeSend a Private Message to BlacktreeEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Lou6t4gto: you got that right ! So the "CONTROL" is a ground ?

Yep. For some reason, GM decided to switch the ground leg of the relay, instead of the power leg. They did the same thing with the radiator fan relay, fuel injectors, etc.

[This message has been edited by Blacktree (edited 02-27-2014).]

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olejoedad
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Report this Post02-27-2014 11:39 AM Click Here to See the Profile for olejoedadClick Here to Email olejoedadSend a Private Message to olejoedadEdit/Delete MessageReply w/QuoteDirect Link to This Post
A lot of newer cars control the ground side of the relay in a multitude of circuits.
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Lou6t4gto
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Report this Post02-27-2014 01:42 PM Click Here to See the Profile for Lou6t4gtoClick Here to Email Lou6t4gtoSend a Private Message to Lou6t4gtoEdit/Delete MessageReply w/QuoteDirect Link to This Post
So, if the ECM has to send power to the relay, to the magnet to close the circuit, to send power to the fuel pump, , WHY didn't it just send the current directly To the fuel pump in the first place?? this is why I don't understand this stuff.
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hookdonspeed
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Report this Post02-27-2014 02:32 PM Click Here to See the Profile for hookdonspeedClick Here to visit hookdonspeed's HomePageClick Here to Email hookdonspeedSend a Private Message to hookdonspeedEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Lou6t4gto:

So, if the ECM has to send power to the relay, to the magnet to close the circuit, to send power to the fuel pump, , WHY didn't it just send the current directly To the fuel pump in the first place?? this is why I don't understand this stuff.


the electro magnet is a low power, very low amp circuit (say like 200ma) the fuel pump is a high amp circuit, (I think a 15Amp?) for them to build the "high amp" circuit into the ecu, it would require much larger ecu's, internal relays, and I high amp line into the ecu itself, creating a lot of un-needed heat inside the unit, causing them to fail ALOT faster, if they did that, it would also require a lot thicker wires running in/out of the ecu rather then the tiny ones you see now.

it also 'separates' circuits, so a failed fuel pump pulling extra power wont effect anything except the fuel pump circuit, and with relays, I could have a relay that was controlled by a 9v battery(or small power pack) control a 220 voltage line in my house to cut it on/off remotely without running the thick wiring to wherever I put the switch (cant see why I would ever need this, but its something that could be done)

[This message has been edited by hookdonspeed (edited 02-27-2014).]

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Lou6t4gto
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Report this Post02-28-2014 12:56 AM Click Here to See the Profile for Lou6t4gtoClick Here to Email Lou6t4gtoSend a Private Message to Lou6t4gtoEdit/Delete MessageReply w/QuoteDirect Link to This Post
Actually, My relay has 5 Wires, not 4. orange/black from the oil sender, Dark green from the ECM, Black to M and ground, a Tan/white AND Tan/black. From what I'm gathering, the Tan/white is "supposed to go" to the Fuel pump and OBD2, But That's where it gets me confused. The fuel pump is already "plugged in" at the firewall to the fuel Pump Power ? ( and the Fuel Level gauge and ground.) isn't that what the 3 wire plug is ?? So where is the Tan/white wire supposed to go if the fuel pump is already wired up ??? also, where is the Tan/Black wire supposed to go ?? Sorry to be such a "dunce" about this. Hoping to get it to Start in a couple of days.
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hookdonspeed
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Report this Post02-28-2014 09:38 AM Click Here to See the Profile for hookdonspeedClick Here to visit hookdonspeed's HomePageClick Here to Email hookdonspeedSend a Private Message to hookdonspeedEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Lou6t4gto:

Actually, My relay has 5 Wires, not 4. orange/black from the oil sender, Dark green from the ECM, Black to M and ground, a Tan/white AND Tan/black. From what I'm gathering, the Tan/white is "supposed to go" to the Fuel pump and OBD2, But That's where it gets me confused. The fuel pump is already "plugged in" at the firewall to the fuel Pump Power ? ( and the Fuel Level gauge and ground.) isn't that what the 3 wire plug is ?? So where is the Tan/white wire supposed to go if the fuel pump is already wired up ??? also, where is the Tan/Black wire supposed to go ?? Sorry to be such a "dunce" about this. Hoping to get it to Start in a couple of days.


ok, heres where things get... 'tricky' the stock fiero wiring was freakign stupid... yes the pumps connected to that 3pin connector, but that goes up front of the car to the fues box, then to the back of the car at the relay, then BACK to the c203 for power. why I recommended the `hot wire`

the factory harness also would get 'power' from the oil pressure sender, if the car had oil pressure, it would get gas. no idea why they did this, but they did, if u look at the relay setup, when `closed` it would get power from the oil pressure switch if oil pressure existed, or would get power from the main power supply if the relay was active, this is why a lot of people have issues with the fuel pump running constantly when the oil pressure switch fails. it also goes to the ALDL(OBD2) port, as the pin is labeled `fuel pump test port`, supplying 12v to it will power the fuelpump, IMO an unneeded thing. (altho its helped to pop my trunk with a dead battery several times.)

[This message has been edited by hookdonspeed (edited 02-28-2014).]

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Lou6t4gto
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Report this Post02-28-2014 01:41 PM Click Here to See the Profile for Lou6t4gtoClick Here to Email Lou6t4gtoSend a Private Message to Lou6t4gtoEdit/Delete MessageReply w/QuoteDirect Link to This Post
Exactly HOW do I "hot wire" it ? (at the "203" ? ) hook a keyed 12 volt up to "what pin", and where do I get the keyed "12 volts From" ? ooh, my head hurts !
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hookdonspeed
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Report this Post02-28-2014 05:55 PM Click Here to See the Profile for hookdonspeedClick Here to visit hookdonspeed's HomePageClick Here to Email hookdonspeedSend a Private Message to hookdonspeedEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Lou6t4gto:

Exactly HOW do I "hot wire" it ? (at the "203" ? ) hook a keyed 12 volt up to "what pin", and where do I get the keyed "12 volts From" ? ooh, my head hurts !


lol.... ok.. heres what ya do... take he relay and harness u have and put it in a bucket some where... goto your local parts store, get a standard 5pin relay and pigtail for it and a weatherpacked inline fuse.

take the harness that goes to your fuelpump and locate the ground and power wires. connect the ground directly to a good ground source, block or frame, whatever, just make sure its a good thick ground wire. now take the +12v feed and connect it to pin 87 of the 5pin relay harness (see above diagram), now from your battery, put the in-line fuse and run the wire to the pin 30 on the relay. that will supply power to your fuel pump when the relay is activated.

now take the fuel pump control wire off your ECU, and connect to pin 85 on the relay, then take pin 86 and run to a ground.

there ya go, your fuel pump now has a direct power feed from the battery.

Please run that by a harness maker or other 3800 expert to make sure i got it right, but that should make you golden.
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