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Hello! I have a 1994 f250 351 with an E4od 4x4. I am experiencing a very loud grinding noise coming from the bottom of the truck around the driver seat. Here is a link to the noise: Link. I got this truck with a rebuilt transmission but there was a ton of **** wrong with it. A few of the things I've replaced related to the noise is the PCM, EPC, trans filter, radiator, transmission cooler, and a trans fluid flush. The PCM replacement fixed a lot of the issues I was having but this noise came out of nowhere. The codes I have for KOEO are 552 and 624. No codes for CM. Codes I have for KOER are 311, 332, and 632. I am stumped and everyplace I go wants me to buy a new transmission when this one barely has 5,000 miles on it and the warranty has expired. I'm to the point where I think I may just drive it till it grenades itself🤷♂️
Is the inspection cover bent, rubbing the flex plate? You're sure it's not a bent brake dust shield? Nothing rubbing against the driveshaft? Have you jacked the tires up to spin them to see if you hear the noise? Looks like you have solenoid related issues. Though written for the IDI diesel section, the basics apply:
Code 624 is the code for an electrical fault between the PCM and the EPC (Electronic Pressure Control) solenoid. With that code present, you'll have either max pressure all the time in the trans, or if it is shorted to ground, minimum pressure. If it is at max pressure, that can cause noises. If it is at minimum pressure, that will cause slippage, which will destroy the transmission. Find and fix the cause of this code. It is usually a damaged wire to the EPC.
Code 624 is the code for an electrical fault between the PCM and the EPC (Electronic Pressure Control) solenoid. With that code present, you'll have either max pressure all the time in the trans, or if it is shorted to ground, minimum pressure. If it is at max pressure, that can cause noises. If it is at minimum pressure, that will cause slippage, which will destroy the transmission. Find and fix the cause of this code. It is usually a damaged wire to the EPC.
Im certain it’s making max out the pressure since the check engine light only comes on sporadically. Maybe a loose wire?
Just found a another forum with you explaining to another feller how to check for short circuits and continuity in the wiring harness. I will test the harness in the morning and report back to you. One question though, what wire/wires am I checking on the PCM side of the harness? Thank you for the help and sharing your knowledge!
You're checking the wires from the PCM to the EPC solenoid. If I had a wiring diagram I could tell you which wires that is, but I don't have a diagram.
You're checking the wires from the PCM to the EPC solenoid. If I had a wiring diagram I could tell you which wires that is, but I don't have a diagram.
I found the wiring diagram for my PCM and it is pin 38. A white wire with a yellow stripe. Circuit 925. Pin 11 on the EPC connector. Here is the video that helped me figure out the pins:
. I have continuity from pin 38 on the PCM connector to pin 11 on the EPC connector. I also have no shorts to ground or power on any of the wires on the EPC connector. I believe that means my wiring is good and my EPC or PCM is bad? If so, is there more testing I can do to determine which one is bad?
Plug the harness into the trans end. Check the resistance between pins 38 and the ground wire. That will give you the resistance of the solenoid. Also check in this configuration for short to ground and short to power.
Plug the harness into the trans end. Check the resistance between pins 38 and the ground wire. That will give you the resistance of the solenoid. Also check in this configuration for short to ground and short to power.
Okay I believe I understand that process. But what wire is the ground wire?
The ground wire is pin 38 on the PCM. The PCM supplies +12v all the time to the solenoid. It turns the solenoid on and off by making or breaking the ground on pin 38.
The ground wire is pin 38 on the PCM. The PCM supplies +12v all the time to the solenoid. It turns the solenoid on and off by making or breaking the ground on pin 38.
I’m a little slow so I’m sorry for not knowing what you’re talking about. But I’m confused when you said to check the resistance between pin 38 and the ground wire on your previous comment. If pin 38 is the ground wire on the PCM side like you said then what other wire or pin am I back probing to test the resistance?