Help with ECU

[Christian08]

Hi all,

I live in Houston, TX and I am an owner of a 2004 Ford Lightning. During the summer the over drive button started to flash. I took it to several mechanics and had some harness issues resolved. However, I was told that I will need to replace the engine computer (4L3A-12A650-AUB) . The explanation that the mechanic gave me was that when he checked the voltage on the transmission it read 8 voltage, but when he checked the voltage on the computer it read 0 voltage. The code is P1747 and mechanic thinks it can be PCM issue or internal transmission issue.

I have had a difficult time trying to find a computer. I saw one online but once I placed the order the vendor stated that they had to "outsource the unit". May I get some guidance and direction on where I can possible get a hold of a computer, please. Do you all think that it can be something else other than the ECU?

 

[01yellercobra]

@Vinnie_B

 

[Vinnie_B]

Hi all,

I live in Houston, TX and I am an owner of a 2004 Ford Lightning. During the summer the over drive button started to flash. I took it to several mechanics and had some harness issues resolved. However, I was told that I will need to replace the engine computer (4L3A-12A650-AUB) . The explanation that the mechanic gave me was that when he checked the voltage on the transmission it read 8 voltage, but when he checked the voltage on the computer it read 0 voltage. The code is P1747 and mechanic thinks it can be PCM issue or internal transmission issue.

I have had a difficult time trying to find a computer. I saw one online but once I placed the order the vendor stated that they had to "outsource the unit". May I get some guidance and direction on where I can possible get a hold of a computer, please. Do you all think that it can be something else other than the ECU?

P1747 ***Output circuit check, generated only by electrical symptoms

Component failure could be: EPC Solenoid, Wiring issue or PCM

Description: EPC solenoid circuit failure, shorted circuit or output driver

Condition: Voltage through EPC solenoid is checked. An error will be noted if tolerance is exceeded

Symptom: Short circuit causes minimum EPC pressure (minimum capacity) and limits engine torque (alternate firm).

There are tests to isolate each of the possible component failure possibilites. An experience Ford Tech should beable to perform this for you.


I have sourced out an ECU for you here About Us - Flagship One. You have the choice to buy it here or send yours in to have it checked Search results for: '4L3A-12A650-AUB'. I recommend most customers here for ECU repairs or replacements. Good luck @Christian08



Lightning FastElectrical Automotive Repair
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Website:https: Lightning Fast Electrical Automotive Repair LLC
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[decipha]

epc is a ground output not voltage

most likely a wiring issue still making a poor connection

 

[Vinnie_B]

epc is a ground output not voltage

most likely a wiring issue still making a poor connection

If you were troubleshooting ELECTRICAL PRESSURE CONTROL (EPC) SOLENOID you would be taking voltage readings!!!


Once the vehicle enters Trans bench mode your going to check to see if the pressure reading matchs the commanded pressure. If it doesnt your going to disconnect transmission harness connector and measure the voltage (5 Volts) on pin 6 at the transmission harness connector to chassis ground. If you have 5 volts there next you will check for battery voltage. You remove the trans fluid pan than Visually inspect the lead frame connectors for damage, than turn the ignition on and Measure the voltage with positive lead to VPWR solenoid pin and negative lead to a good ground for a voltage greater than 10 volts. If thats good next you will check for electrical signal. You gonna Measure the voltage with positive lead connected to VPWR solenoid pin and connect negative lead to the signal pin of the EPC solenoid and check if voltage and solenoid state changes. Im not going to go on from here. My point is you do take voltage readings diagnosing this issue. I would never purposely give out wrong information to a member!!!! Maybe you misunderstood me or I misunderstood your reply?

 

[decipha]

Thats instructions for idiots. Please never share that crap again.

The EPC is a ground duty cycle output.
Check it at the ecu connector to verify the ecu is functioning correctly.

No one gives two shits about the transmission he asked specifically about the ecu and having to replace it.

No need in replacing it if its functioning correctly.

 

[Dusten]

He's had a melted trans harness and is still having issues. I can almost guarantee the harness is still an issue. We've been helping him over in lightning rodder.

 

[Vinnie_B]

He's had a melted trans harness and is still having issues. I can almost guarantee the harness is still an issue. We've been helping him over in lightning rodder.

Thanks for the tip @Dusten . I would agree with this most likely being a wiring issue if there was damage to the harness.

 

[GerryMX]

He's had a melted trans harness and is still having issues. I can almost guarantee the harness is still an issue. We've been helping him over in lightning rodder.

We may deal with the wiring issue on my uncle's new Lightning project. The previous owner mentioned the trans harness melted once. We'll take a look when it returns from the shop for the mounting of new tires from 4Wheelonline this week.