Cel....trying To Check Codes. No Grey Plug?

[First5.001]

My CEL has been on since I got the car. Cleared codes, came back. Last night I went to check them, but there's no grey connector. Just the big one and the brown one. Everything I read said not to use that one...after I already tried it. I'm not sure if someone cut the other one, or what. I've checked CELs on Ford's before so I know what it looks like. Any suggestions?

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[Mustang5L5]

Brown one is hood light.

Follow the big one down to where it enters the harness. You may need to remove some tape or plastic retainer to expose the wiring. Do you find a broken wire down there somewhere?


What year is this car?

 

[First5.001]

Didn't see any wires that were cut. I'll do more digging in the daylight after work. It's a 89.

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[Mustang5L5]

Should be the same as my '88 then.

Pretty much coming from same spot

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[jrichker]

Do the simple stuff - unless you are color blind...

Check the wire color - the gray connector is connected to white/red wire - look for the wire...

Look for pin 48 on the computer wiring harness connector. This is where the white/red wire connects to the computer.

The following are diagrams courtesy of Tmoss & Stang&2birds

Complete computer, actuator & sensor wiring diagram for 88-91 Mass Air Mustangs

See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host) for help on 88-95 wiring; http://www.veryuseful.com/mustang/tech/engine/ Everyone should bookmark this site.

94-95 Mustang wiring diagrams
http://www.veryuseful.com/mustang/tech/engine/#95-95Diagrams

Complete computer, actuator & sensor wiring diagram for 91-93 Mass Air Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/91-93_5.0_EEC_Wiring_Diagram.gif

Complete computer, actuator & sensor wiring diagram for 88-91 Mass Air Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/88-91_5.0_EEC_Wiring_Diagram.gif

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

Fuel, alternator, A/C and ignition wiring
http://www.veryuseful.com/mustang/tech/engine/images/fuel-alt-links-ign-ac.gif

O2 sensor wiring harness
http://www.veryuseful.com/mustang/tech/engine/images/mustangO2Harness.gif

Vacuum diagram 89-93 Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/mustangFoxFordVacuumDiagram.jpg

HVAC vacuum diagram
http://www.veryuseful.com/mustang/tech/engine/images/Mustang_AC_heat_vacuum_controls.gif

TFI module differences & pin out
http://www.veryuseful.com/mustang/tech/engine/images/TFI_5.0_comparison.gif

Fuse box layout
http://www.veryuseful.com/mustang/tech/engine/images/MustangFuseBox.gif

Mustang 5.0 Lights and Radio schematic, by TMoss:
http://www.veryuseful.com/mustang/tech/engine/images/mustangFoxLights-Radio_diag.gif

87-92 power window wiring
http://www.veryuseful.com/mustang/tech/engine/images/mustang87-92 PowerWindowWiring.gif

93 power window wiring
http://www.veryuseful.com/mustang/tech/engine/images/mustang93PowerWindows.gif

T5 Cutaway showing T5 internal parts
http://www.veryuseful.com/mustang/tech/engine/images/5_Speed_Cutaway_Illustrated.jpg

Visual comparison of the Ford Fuel Injectors, picture by TMoss:
http://www.veryuseful.com/mustang/tech/engine/images/Ford_Injector_Guide.jpg

Convertible top motor wiring http://www.veryuseful.com/mustang/tech/engine/images/mustang88VertTopMotorCkt.gif

Engine mounted fuel injector harness
http://www.veryuseful.com/mustang/tech/engine/images/mustangEngineHarness.gif

Location of the TPS, IAB, and the 10-pin connectors on a 5.0, picture by TMoss:
http://www.veryuseful.com/mustang/tech/engine/images/TPS_IAB_Pic.jpg

Starter circuit
http://forums.stangnet.com/attachment.php?attachmentid=21328&d=1080916057

 

[First5.001]

Thanks for the links. I suppose I'll start at the computer and work my way out

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[First5.001]

Picked at the harness. This was the only red/white wire I could find in the harness.

Should I just put a pin in it and use it?

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[jrichker]

Use the ohmmeter function to make sure it goes back to pin 48 on the computer wiring harness. If it does, then jumper it to the black/white wire, turn the ignition to Run and the codes should dump.

 

[First5.001]

Good thinking. I'll try that after work.

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[First5.001]

No luck. Tried a the white wire with a red tracer, a red wire with a white tracer and nothing. Solid cel. Any other methods?

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[Mustang5L5]

Is this harness original to the car as far as you know? Original 5.0 car?


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[Mustang5L5]

No luck. Tried a the white wire with a red tracer, a red wire with a white tracer and nothing. Solid cel. Any other methods?

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The wire is more yellow/orange with a thin red tracer

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[jrichker]

The wire is more yellow/orange with a thin red tracer

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Time. dirt and heat take their toll on wire colors in the engine compartment.

Find someone with a telephone line toner tool and connect the tone generator to pin 48 on the computer and then use the listener to trace the wire in the engine compartment.

See

View: https://www.youtube.com/watch?v=OyJsXpVZc5E
OR

View: https://www.youtube.com/watch?v=jP0AtN9hTP4

to learn how it works...

The first video uses a Harbor Freight http://www.harborfreight.com/cable-tracker-94181.html toner set - cost is ~$25.

There may be better quality or cheaper versions of this tool, but the best bet is to find a friend who has one of these tools and persuade him to help you.

 

[First5.001]

As far as I'm aware it's stock to the car. The dirt and grease matches the rest of the engine bay. Again, pretty sure it's a factory 5.0/5 speed car. In the diagrams it's showing I can see a white wire with a red tracer. So that appears to be it, but there's no "dead end" where a plug would go. I have a power probe with the screw on wire piercing leads, I traced the white/red wire to the computer, but it doesn't appear to be in 48. I pierced it under the hood and linked it to the test lead in the plug. No luck.

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[First5.001]

Here is where it goes into the ecm.

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[jrichker]

Go back and find pin 48 using the diagram for the wire side of the computer wiring plug and see what color the wire is. Then chase that wire out to the self test connector area and see if it is there.

 

[First5.001]

Ok. I have to figure out what way the computer plug and diagram are oriented so I know where it is. Almost looks like that spot in blank on my ecm.

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[First5.001]

I noticed even after having the battery disconnected for an hour the cel is still on the first start. Shouldn't it reset when the battery is disconnected?

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[Mustang5L5]

I noticed even after having the battery disconnected for an hour the cel is still on the first start. Shouldn't it reset when the battery is disconnected?

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It should, unless the fault is a major fault that the eec sees pretty much immediately


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[First5.001]

Gotcha. Really wish I could find the wire to check it. The only plug near it is the brown connector with the black/yellow wire. Did ford maybe use that one in 89? Anyway I can test the wire add not damage anything?

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