I Need Pics Of Engine Harness Plugs And Locations

which plugs are you looking for to start with?

Have you inspected the new harness for broken or damaged wires? I think there are write ups (google search) for identifying what year harness you may have.

For the most important wires, like the EFI harness, it's really difficult to cross up the connectors incorrectly since they are either color coded on the plugs or have a specific pattern that won't fit in any other plug but the correct one.

Couple more things, with key on, do you have power to anything else? Like headlights? tail lights and turn signals? Dash lights? Does the coil have juice?

How did you run your grounds? Your battery is still in your engine bay right?

From the Cranks OK, but No Start Checklist for Fuel Injected 5.0 Mustangs model years 1986-1995

Note: 94-95 specific changes are in red

1.) Remove push on connector (small red/blue wire) from starter solenoid and turn ignition switch to the Run position. Place car in neutral or Park and set the parking brake. Remove the coil wire from distributor & and hold it 3/8” away from the engine block. Jumper the screw to the big bolt on the starter solenoid that has the battery wire connected to it. You should get a nice fat blue spark.
Most of the items are electrical in nature, so a test light, or even better, a voltmeter, is helpful to be sure they have power to them.

No spark, possible failed items in order of their probability:
A.) MSD, Crane, or other ignition box if present - Bypass it and return to stock configuration if possible. Do this as a temporary measure to eliminate it as a possible problem source.
B.) PIP sensor in distributor. The PIP sensor supplies the timing pulse to trigger the TFI and injectors. A failing PIP sensor will sometimes let the engine start if the SPOUT is removed. See paragraph 5A – Using a noid light will tell if the PIP is working by flashing when the engine is cranking.
C.) TFI module: use a test light to check the TFI module. Place one lead of the test light on the red/green wire on the ignition coil connector and the other lead on the dark green/yellow wire on the ignition coil connector. If the TFI is working properly, the test light will flash when the engine is cranked using the ignition switch.
D.) Coil
E.) No EEC or computer power - EEC or computer relay failure
86-93 models only: EEC relay next to computer - look for 12 volts at the fuel injector red wires.
94-95 models only: EEC or PCM power relay in the constant control relay module. Look for 12 volts at the fuel injector red wires.
Both 86-93 and 94-95 models: No 12 volts with the ignition switch in the run position on the fuel injector red wires. The relay has failed or there is no power coming from the ignition switch. Make sure that there is 12 volts on the red/green wire on the coil before replacing the relay.
F.) No EEC or computer power - fuse or fuse link failure
86-93 models only: Fuse links in wiring harness - look for 12 volts at the fuel injector red wires. All the fuse links live in a bundle up near the starter solenoid. Look for a 20 gauge blue fuse link connected to 2 black/orange 14 gauge wires.
94-95 models only: 20 amp EEC fuse in the engine compartment fuse box. Look for 12 volts at the fuel injector red wires.
G.) Ignition switch - look for 12 volts at the ignition coil red/lt green wire. No 12 volts, blown fuse link or faulty ignition switch. Remove the plastic from around the ignition switch and look for 12 volts on the red/green wire on the ignition switch with it in the Run position. No 12 volts and the ignition switch is faulty. If 12 volts is present in the Run position at the ignition switch but not at the coil, then the fuse or fuse link is blown.
Note: fuses or fuse links blow for a reason. Don’t replace either a fuse or fuse link with one with a larger rating than stock. Doing so invites an electrical fire.
Ignition fuse links may be replaced with an inline fuse holder and 5 amp fuse for troubleshooting purposes.
94-95 models only: Check inside fuse panel for fuse #18 blown – 20 amp [fuse
H.) Missing or loose 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.
In 86-90 model cars, it is a black cylinder about 2 1/2" long by 1" diameter with a black/lt green wire.
In 91-95 model cars it is a black cylinder about 2 1/2" long by 1" diameter with a black/white wire.
You'll find it up next to the starter solenoid where the wire goes into the wiring harness
Wiring Diagrams:

See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host) for help on 88-95 wiring Mustang FAQ - Engine Information Everyone should bookmark this site.

Ignition switch wiring


Fuel, alternator, A/C and ignition wiring


Note that the below diagram shows the connector shape for the sensors
Complete computer, actuator & sensor wiring diagram for 88-91 Mass Air Mustangs

stangboy said:

My buddy said just 1 light came on on the dash, we didn't check the headlights, and no, the coil did not have juice.

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Do the checklist I posted, one step at a time. Do not skip any steps, you might miss the one thing you need to find and fix the problems. The diagrams will help you chase the missing 12 volts starting at the ignition switch and working your way out.

If you have no 12 volts at the ignition coil with the switch in the Run position, be sure to start checking for voltage at the ignition switch.

stangboy said:

What year harness is this supposed to be for. I think this is the harness I have. I wasn't sure what plug 32 and 33 were and this says they are for fuel pump relay and WOT a/c cutoff. I know that the original fuel pump relay on my car is under the driver seat(or am I mistaken). So with that being said, this must be the diagram for a 90-93 harness??

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Correct. I believe that's the only difference, however. The other differences would be wire color within the harness itself, but you can easily figure them out. I just went over mine last year for a similar issue, pretty much wire by wire chasing what caused my non-powered fuel pump issue. I have a '92, but the wiring diagram I had was up to '89, I believe. Between the diagram and some text-based info from forums, I was able to easily figure out what was what when they didn't match the diagram.

Do the checklist above though, it's really important. Once you get through them you'll either find your issue or will have a very limited list of possible causes left over.

"where did this pic come from? "

A post almost 4 years ago?