EEC relay not getting power.

Hello everyone, I'm a new member to these forms however I have been using them with help diagnosing an issue I have been having. It started when I went start the car so I could move it out of the way of the car port gate so I could get another one of my project cars out. I went to start it and all it did was crank but it wouldn't fire and that's when I noticed the fuel pump wasn't running. I thought that the junkyard fuel pump I put in it had crapped out and dropped the tank again only to find out it's not the problem and it's gone from there. I've been able to get the pump to run by jumping the EEC relay across and grounding the fuel pump relay so I know all that wiring is good. The part that seems to have an issue is that when I test the red/green power wire for the EEC relay it doesn't have 12V to it. I then checked to see if I had resistance and continuity and I do so I feel like it's safe to say that the wire isn't completely open. I have also checked if I got 12V at the ignition switch and I do so it doesn't make sense as to why I'm only getting 17mV to the EEC relay. Another thing is I have no idea where the 20g blue fusible link that is suppose to be in the circuit after the ignition switch would be cause I'd like to see if it's opened and has slightly grounded itself. I have tried everything I can think of and am stumped so I'm wondering if anyone else has had this problem. If they have it would be great to hear from you! I should probably note it is a 89 LX 2.3L 5 speed that I'm planning on swapping a V8 and 6 speed into once I get the body stiffened up.
 
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@GoldenFox89



Fuel Pump Troubleshooting for 87-90 Mustangs

Revised 1-Dec-2015 to add fuse links diagram.

Clue – listen for the fuel pump to prime when you first turn the ignition switch on. It should run for 1-3 seconds and shut off. To trick the fuel pump into running, find the ECC test connector and jump the connector in the upper LH corner to ground.

Foxbody Diagnostic connector
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Foxbody Diagnostic connector close up view
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Turn the ignition switch on when you do this test.
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If the fuse links are OK, you will have power to the pump. Check fuel pressure – remove the cap from the Schrader valve behind the alternator and depress the core. Fuel should squirt out, catch it in a rag. A tire pressure gauge can also be used if you have one - look for 37-40 PSI. Beware of fire hazard when you do this.

No fuel pressure, possible failed items in order of their probability:
A.) Tripped inertia switch – press reset button on the inertia switch. The hatch cars hide it under the plastic trim covering the driver's side taillight. Use the voltmeter or test light to make sure you have power to both sides of the switch

B.) Fuel pump power relay – located under the driver’s seat in most Mustangs built before 92. See the diagram to help identify the fuel pump relay wiring colors. Be sure to closely check the condition of the relay, wiring & socket for corrosion and damage.
C.) Clogged fuel filter
D.) Failed fuel pump
E.) Blown fuse link in wiring harness.
F.) Fuel pressure regulator failed. Remove vacuum line from regulator and inspect for fuel escaping while pump is running.

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The electrical circuit for the fuel pump has two paths, a control path and a power path.

Control Path
The control path consists of the inertia switch, the computer, and the fuel pump relay coil. It turns the fuel pump relay on or off under computer control. The switched power (red wire) from the ECC relay goes to the inertia switch (red/black wire) then from the inertia switch to the relay coil and then from the relay coil to the computer (tan/ Lt green wire). The computer provides the ground path to complete the circuit. This ground causes the relay coil to energize and close the contacts for the power path. Keep in mind that you can have voltage to all the right places, but the computer must provide a ground. If there is no ground, the relay will not close the power contacts.


Power Path
The power path picks up from a fuse link near the starter relay. Fuse links are like fuses, except they are pieces of wire and are made right into the wiring harness. The feed wire from the fuse link (orange/ light blue wire) goes to the fuel pump relay contacts. The fuse links are in a bundle up near the starter relay; you will have to unwrap the wiring harness to find them.

Fuse links
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Fuse links come with a current rating just like fuses. A clue as to what current they are designed for is to look at the size wire they protect. Fuse link material is available at most good auto parts stores. There may even be a fuse link already made up specifically for your car. Just be sure to solder the connection and cover it with heat shrink tubing.

Heat shrink tubing is available at Radio Shack or other electronics supply stores.

See the video below for help on soldering and heat shrinking wiring. There is a lot of useful help and hints if you don’t do automotive electrical work all the time.


View: http://youtu.be/uaYdCRjDr4A


When the contacts close because the relay energizes, the power flows through the contacts to the fuel pump (light pink/black wire). Notice that pin 19 on the computer is the monitor to make sure the pump has power. The fuel pump has a black wire that supplies the ground to complete the circuit.

Remember that the computer does not source any power to actuators, relays or injectors, but provides the ground necessary to complete the circuit. That means one side of the circuit will always be hot, and the other side will go to ground or below 1 volt as the computer switches on that circuit.

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Now that you have the theory of how it works, it’s time to go digging.

All voltage reading are made with one voltmeter lead connected to the metal car body unless otherwise specified

Check for 12 volts at the red wire on the inertia switch. No 12 volts at the inertia switch, the ignition switch is turned off or faulty or there is no power to the EEC (computer) power relay. To be sure look for good 12 volts on the red wire on any fuel injector.
Good 12 volts means the EEC relay is working. No 12 volts and the ECC wiring is at fault.
Look for 12 volts on the red/green wire on the ignition coil: no 12 volts and the ignition switch is faulty, or the fuse link in the ignition power wire has blown. No 12 volts here and the ECC relay won’t close and provide power to the inertia switch. Check the Red/black wire on the inertia switch, it should have 12 volts. No 12 volts there, either the inertia switch is open or has no power to it. Check both sides of the inertia switch: there should be power on the Red wire and Red/Black wire. Power on the Red wire and not on the Red/Black wire means the inertia switch is open. Push the button on the side of it to reset it, and then recheck. Good 12 volts on one side and not on the other means the inertia switch has failed.

Look for 12 volts at the Orange/Lt. Blue wire (power source for fuel pump relay). No voltage or low voltage, bad fuse link, bad wiring, bad ignition switch or ignition switch wiring or connections. There is a mystery connector somewhere under the driver’s side kick panel, between the fuel pump relay and the fuse link.

Turn on the key and jumper the fuel pump test connector to ground as previously described. Look for 12 volts at the Light Pink/Black wire (relay controlled power for the fuel pump). No voltage there means that the relay has failed, or there is a broken wire in the relay control circuit.

Pump wiring: Anytime the ignition switch is in the Run position and the test point is jumpered to ground, there should be at least 12 volts present on the black/pink wire. With power off, check the pump ground: you should see less than 1 ohm between the black wire and chassis ground.


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The yellow wire is the fuel tank sender to the fuel quantity gage. The two black wires are grounds. One ground is for the fuel tank sender and the other is the fuel pump. The ground for the fuel pump may be larger gauge wire that the fuel tank sender ground wire.

Make sure that the power is off the circuit before making any resistance checks. If the circuit is powered up, your resistance measurements will be inaccurate.

You should see less than 1 Ohm between the black wire(s) and ground. To get some idea of what a good reading is, short the two meter leads together and observe the reading. It should only be slightly higher when you measure the black wire to ground resistance.

The Tan/Lt Green wire provides a ground path for the relay power. With the test connector jumpered to ground, there should be less than .75 volts. Use a test lamp with one side connected to battery power and the other side to the Tan/Lt Green wire. The test light should glow brightly. No glow and you have a broken wire or bad connection between the test connector and the relay. To test the wiring from the computer, remove the passenger side kick panel and disconnect the computer connector. It has a 10 MM bolt that holds it in place. With the test lamp connected to power, jumper pin 22 to ground and the test lamp should glow. No glow and the wiring between the computer and the fuel pump relay is bad.

Computer: If you got this far and everything else checked out good, the computer is suspect. Remove the test jumper from the ECC test connector located under the hood. Probe computer pin 22 with a safety pin and ground it to chassis. Make sure the computer and everything else is connected. Turn the ignition switch to the Run position and observe the fuel pressure. The pump should run at full pressure.
If it doesn't, the wiring between pin 22 on the computer and the fuel pump relay is bad.
If it does run at full pressure, the computer may have failed.

Keep in mind that the computer only runs the fuel pump for about 2-3 seconds when you turn the key to the Run position. This can sometimes fool you into thinking the computer has died. Connect one lead of the test light to power and the other lead to computer pin 22 with a safety pin. With the ignition switch Off, jumper the computer into self test mode like you are going to dump the codes. Turn the ignition switch to the Run position. The light will flicker when the computer does the self test routine. A flickering light is a good computer. No flickering light is a bad computer.
Remove the test jumper from the ECC test connector located under the hood.

Fuel pump runs continuously: The fuel pump relay contacts are stuck together or the Tan/Lt Green wire has shorted to ground. In extreme ghetto cases, the pump relay may have been bypassed. Remove the fuel pump relay from its socket. Then disconnect the computer and use an ohmmeter to check out the resistance between the Tan/Lt Green wire and ground. You should see more than 10 K Ohms (10,000 ohms) or an infinite open circuit. Be sure that the test connector isn’t jumpered to ground.
If the wiring checks out good, then the computer is the likely culprit.


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Prior to replacing the computer, check the computer power ground. The computer has its own dedicated power ground that comes off the ground pigtail on the battery ground wire. Due to it's proximity to the battery, it may become corroded by acid fumes from the battery. It is a black cylinder about 2 1/2" long by 1" diameter with a black/lt green wire. You'll find it up next to the starter solenoid where the wire goes into the wiring harness

If all of the checks have worked OK to this point, then the computer is bad. The computers are very reliable and not prone to failure unless there has been significant electrical trauma to the car. Things like lightning strikes and putting the battery in backwards or connecting jumper cables backwards are about the only thing that kills the computer.

See the following website for some help from Tmoss (diagram designer) &
Stang&2Birds (website host)

http://www.veryuseful.com/mustang/tech/engine/images/IgnitionSwitchWiring.gif

http://www.veryuseful.com/mustang/tech/engine/images/fuel-alt-links-ign-ac.gif

http://www.veryuseful.com/mustang/tech/engine/images/88-91eecPinout.gif
 
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I previously did all the testing described above and found that most of the wiring is good the only thing is I don't have 12V at the ignition coil, TFI module, or the EEC relay. I do however have 12V right at the ignition switch and to the door chime circuit. In the diagram for the ignition switch it shows there being a fusible link in the red/green circuit AFTER the ignition switch and the door chime splice. It states it's a 20g blue link but I have no idea where it is. Is it in the main harness going through the dash or in the one that goes through the fire wall? If no one knows for sure I think I just cut it after the ignition switch and run a new wire. It would be easier to do that then to pull the dash to tear into the main harness.
 
None of the fusible links near the starter solenoid are blow. I've check them several times to make sure regardless the fusible link I am looking for is in the red light green wire. According to my Hanes manual wiring diagrams the link in question is identified as fusible link "N". Is there any other location for fusible links known to be? I believe it's under the dash someplace since there is no fusible link in the red green wire under the hood, I checked by opening up the wiring harness to look for it. I did find the splice for the ignition coil and the TFI module as well as the red green wire going to either connect c403 or c201, I can't remember off the top of my head.
 
How did you determine that none of the fusible links near the starter solenoid are blown?
Continuity check does not work, 1 strand of wire will show good even if the remaining are melted.
EEC Relay is D & G.
I can't find N on any of the Ford drawings.
632508
632510

BTW, the entire EVTM is here:
 
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Ah beauty, I use to have access to the factor manuals back when I was working at a Ford Dealership, now all I got access to is Mitchell in which I can't print anything off for personal use and the good ol' Hanes manual. Anyways I know they aren't blown because I physically felt each one of them and gave them a gentle tug for good measure. As for what you mean for continuity I know it can literally be one single strand and you'll still get it hence why I think it may be starting to break off fusible link "N". Go to page 21 and follow the red/green wire or the brown/pink wire and you'll find link "N" in the circuit there. It has to be under the dash someplace but where is the question.
 
It says it's in the wiper motor harness dumb thought but I will ask anyways though I almost 100% sure it shouldn't but having the wiper motor unplugged shouldn't hurt anything should it? I'll feel really fudgin' stupid if I plug the new wiper motor, (old one was noisy as all hell), in and I get voltage where it needs to go...
 
Yeah I figured it had nothing to do with the wiper motor. It's just that the picture on page 19 vaguely shows it being in the wiper motor harness which it's not. However I found the link under the hood and I think I've found the issue. It may have been self inflicted but I'm not sure. Anyways the link is practically broken. I can fold it 180 degrees. Looks like I buying fusible link wire tomorrow.
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The only way you can burn that up is to short circuit the EEC relay coil or short pin-86 of the relay to the body.
In normal use, the relay coil draws about 1/4 amp. 20ga fuse link is probably the smallest there is. Parts stores have no smaller than 18ga. Amazon has them.
Fuselinks are sized 2 wire gauges smaller than the wire they are protecting (16ga).
 
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If it was burned wouldn't it burn right in half? This one feels more like it's been kinked/pinched and broken since it's still in one piece. The relay is a 5 pin numbered 1 thur 5 so pin 1 would be 86 but that circuit does go straight to ground through pin 2 when power is turned on at pin 1. Also why the hell are they using a 20ga fuse link if it's a 16ga wire? Wouldn't they use a 18ga to protect it or is the wire 18ga? I haven't had a chance to measure the wire. Summit Racing also has a 20ga fusible link, must be a new old stock from Pico because Pico no longer makes them.
 
If it was burned wouldn't it burn right in half?
This one feels more like it's been kinked/pinched and broken since it's still in one piece. The relay is a 5 pin numbered 1 thur 5 so pin 1 would be 86 but that circuit does go straight to ground through pin 2 when power is turned on at pin 1. Also why the hell are they using a 20ga fuse link if it's a 16ga wire? Wouldn't they use a 18ga to protect it or is the wire 18ga? I haven't had a chance to measure the wire. Summit Racing also has a 20ga fusible link, must be a new old stock from Pico because Pico no longer makes them.
Absolutely NOT. The link I provided will answer your questions.

Fusible links perform the same basic function as fuses, but they go about it in a slightly different way. In automotive applications, a fusible link is a length of wire that is several gauges thinner than the wire that it is designed to protect. When all goes well, this results in the fusible link failing, and breaking the circuit, before the protected wiring can fail.

In addition to simply being thinner than the rest of the wire in a circuit, fusible links are also encased in special materials that are designed to not catch on fire when exposed to high temperatures. So while extremely high current in a regular wire may cause a fire, a blown fusible link is less likely to do so.
 
I'm still alittle confused by this because it honestly doesn't seem burnt out. It looks like it got pinched somehow and broke since it still feels solid on either side of the pinched spot. Wouldn't I be able to stretch the sheathing out if it was burnt out? Also how would that particular fuse link burnt out? Would extended cranking do it because I'm not entirely sure what would have cause it to. Also won't the circuit be completely open if the link was burned out? I had a resistance value and continuity at the EEC relay plug so it's obviously not completely open.
 
I'm still alittle confused by this because it honestly doesn't seem burnt out. It looks like it got pinched somehow and broke since it still feels solid on either side of the pinched spot. Wouldn't I be able to stretch the sheathing out if it was burnt out? Also how would that particular fuse link burnt out? Would extended cranking do it because I'm not entirely sure what would have cause it to. Also won't the circuit be completely open if the link was burned out? I had a resistance value and continuity at the EEC relay plug so it's obviously not completely open.
Do a voltage drop test...
A good fuse link will drop no more than 200 millivolts

See http://assets.fluke.com/appnotes/automotive/beatbook.pdf for help troubleshooting voltage drops across connections and components.

Be sure to have the maximum load on a circuit when testing voltage drops across connections. As current across a defective or weak connection, increases so does the voltage drop. A circuit or connection may check out good with no load or minimal load, but show up bad under maximum load conditions.

Voltage drops should not exceed the following:
200 mV Wire or cable
300 mV Switch
100 mV Ground
0 mV to <50 mV Sensor Connections
0.0V bolt together connections

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So I already did test for voltage on that wire before searching for the link. I had 17mv, continuity and next to no resistance so I would say it's safe to say that link is damaged in one way or another? Either way I got one coming from Summit Racing for $20. That includes shipping costs since I live in Canada.