Looking for Wiring Diagram 2004 Mustang GT - Ford Mustang Forum
 
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post #1 of 5 (permalink) Old 09-15-2019 Thread Starter
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Looking for Wiring Diagram 2004 Mustang GT

Hey Guys have a 2004 Mustang GT that just rebuilt engine in(bought it with mechanical issues) got motor back in and have no coil ground pulse for cylinder 5-7 or 8.....checked the wiring as much as possible for corrosion and grounds. Starting to lean to probability of bad ECU. Can't find a wiring diagram on line so if any seasoned stangers have any tips appreciate it.....Also changed out the tranny range selector because there is no upshift on gears(strong low and reverse gear). didn't help car sat two years so may have internal issues....anyway appreciate any tips....

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post #2 of 5 (permalink) Old 4 Weeks Ago
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Just wondering. Have you CONFIRMED +12 volts of key on power at all of the COP connectors? Have you confirmed that the supply is able to carry a real current?

Have you measured the resistance of each COP?

Have you "rung out" the signal return lines from the COP to the PCM connector?

5 LG/YE #27
6 OG/YE #1
7 PK/LB #78
8 WH/RD #79

Any evidence of water or rodent activity especially around the PCM?

Do you have an ODB2 scanner? Are there any DTC codes? Usually if a bad PCM Coil driver will set a DTC code. An ODB2 scanner with bi-directional capabilities can be a big help as allowing you to test individual lines.

ForScan ODB2 scanner w ELM327 USB
https://www.stangnet.com/mustang-for...elm327-usb.57/


2003 GT Convertible (sold & missed)
2000 GT coupe (Craigslist project. Fixed. Now my DD). Windsor to Romeo swap.
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post #3 of 5 (permalink) Old 4 Weeks Ago Thread Starter
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Thanks

Thank you for obviously a pro's advice....there were coil codes that i cleared to see if they reset.They reset as follows PO354-355-356-358 ....coil malfunction. I also got P1237 Man fuel control error. I probed each red wire at coil....all 12 volts . checked ground pulse all show pulse with flashing 12 v test light to Pos side of battery except....5-7-8.....I don't know enough about the coil over plug coils ecu setup to know if the same switching diode shuts signal on and off......traced the ground wires back to connector.....under hood....seemed good to there but pulled ecu pin connector off ecu and looks like the color coded are different than at the coil ground.....if u could find time could u email me at [email protected].....I can tell this definitely isn't your first Rodeo and could use your help.....thank u so much Larry..ps does the 04 have a separate Tranny control module Thank you so much for your help

Last edited by lstill; 4 Weeks Ago at 02:57 PM. Reason: Adding information
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post #4 of 5 (permalink) Old 4 Weeks Ago
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No. The 1999-2004 model year Mustangs do NOT have a separate transmission control module.

The fuel injectors and the COP ignition are "ground start" devices. This means there is a constant +12 volts present the whole time the key is on. The circuit is completed by the PCM grounding the signal return line.

Anytime the PCM calls out a DTC with a "circuit malfunction" DTC it means there's something soooooooo wrong with the circuit that the PCM is unable to perform any trouble shooting.

Have you swapped in a known good COP to one of the positions throwing a DTC? The idea is to see if the DCT follows the device or stays on the original cylinder.

Do you have a test light? To test for a short to ground, put the test light pig tail on battery positive. Probe the device's signal return line. A short to ground will cause the test light to be constantly on.

To test for an open in the signal return lines is what is done by "ringing out" the line. My wiring diagrams indicates that the wire colors do NOT change from what was posted when going through any connectors. Suggest that you double check your work (or you may be looking straight at your problem).


>>
P0351 Through P0360 - Ignition Coil A through J Primary/ Secondary Circuit Malfunction

Open or short in Ignition START/RUN circuit
Open coil driver circuit
Coil driver circuit shorted to ground

Damaged coil
Damaged PCM
Coil driver circuit shorted to VPWR


P1237 - Fuel Pump Secondary Circuit Malfunction

Open or shorted FP PWR circuit
Open FP RTN circuit to FPDM
Open or shorted circuit in the fuel pump
Locked fuel pump rotor
Damaged FPDM

2003 GT Convertible (sold & missed)
2000 GT coupe (Craigslist project. Fixed. Now my DD). Windsor to Romeo swap.
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post #5 of 5 (permalink) Old 4 Weeks Ago Thread Starter
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Thank u so much again.....one other thing ive found is that the AT control harness wasn't plugged back in to the main harness....that explains having to start the car by applying 12 volts to starter solenoid and the transmission codes. I can't find a way to reach down and pull the at wiring connector up to plug it in....don't know if i can pull console and access it thru inside of car....there is just no room to reach behind the motor and pull it up.....any ideas appreciated ill ring the return lines from pcm and keep looking....thank u so much again.....
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