1995 FORD PSOM Repair
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- เผยแพร่เมื่อ 23 ส.ค. 2024
- FORD PSOM - 1995 E-350 van.
I had no odometer showing, and the transmission was shifting harshly. I followed two other youtube videos in my efforts to repair this.
Bassguitarist1985 (has the Mouser parts list I followed)
• 1995 Ford PSOM Repair
shadowrider460
• 1995 Ford F-250 4X4 PS...
I did the parts replacement and it still didn't work. So I bought another unit from ebay and compared signals with my broken unit.
I determined that an internal trace in the board between the + side of the electrolytic, the + side of the MOV, and the transistor collector (point C) was broken. I added a wire jumper on the bottom of the circuit board and the unit now powers up.
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You are my hero. Just saved me $200+. I had replaced my capacitors and got nothing. Did your jumper wire trick, and I am working.
This worked for my truck after speedometer and odometer quit working simultaneously. Great video!
Thank you so much! replaced all the components and nothing but I tried your fix and now it's working as it's supposed to!
Your video helped me fix my PSOM, but I also found a minor flaw in how you did it. I found that if I jumper from the MOV to the collector on Q5 the PSOM came back to life, but you will have a 30mA battery draw with the key off because you are not allowing Q5 to turn off the circuit that it controls. On my PSOM I found a damaged trace between the Base of Q5 and Pin 1 on IC1. Jumping that trace repaired the PSOM and the battery draw with the key off is 5mA. There is a partial schematic for this board online. Also the Q5 collector trace is hard to see, but it is on the top layer and runs straight back between the other pins. I spent a lot of time with a magnifier and a flashlight while troubleshooting mine.
I would very much like to see the schematic!
I was wrong about an embedded trace. I see now that there is a pass-through near R8 which connects from the Q5 collector trace on the back of the board to the diode D1. It was the neighborhood of D1 that was destroyed on my board by capacitor leakage.
My trace to IC1 looks good.
When electrolytic capacitors leak they can take out traces all around them from the acidic goo.
I don't know what to say about the 30mA/5mA. I think the base of Q5 should control whether Q5 is on or off.
www.ford-trucks.com/forums/1534463-e4od-slams-when-warm-rebuild-psom.html
Basically when you connect power to the collector on Q5 you are bypassing Q5. That will keep part of the circuit alive when It should be off and will cause a small battery drain. If the vehicle was driven regular it wouldn't be a problem, but if the truck sits a lot then the battery would drain faster while parked.
My trace looked good, but it had electrolyte type corrosion in one spot. I wouldn't have caught it without the meter.
Thanks it worked like a charm
Thank you so much! This got my truck working amazing again. Thank you for putting the time to share this information.
Read the comments. At least one person found what they thought was a flaw in my process, and you should check that out.
So my odometer is lit up at the mileage but tue speedometer does not work and the transmission need to be manually shifted into drive. Also sometimes it will not shift from second gear unless the overdrive light on the shifter blinks on and off? Does that sound like a PSOM issue?
Was your vehicle ever wanting to stall or completely stalling going into reverse, idling rough? Or any gear specifically. I've had my E4OD trans rebuilt(won't go into that, but they either did a poor diagnosis or didn't fix the original issue if it was the trans itself), tried everything I can possibly think of or find online and I came across a PSOM repair walkthrough today and the symptoms are somewhat similar to mine.
Does your speedometer work?
Check that.... does your odometer work? Mine the odometer was blank and the shifting was hard.
The issue is internal to the transmission. What happens is, there is a fluid pressure leak from the reverse circuit, to the Torque Converter Clutch apply circuit. So it's the same as releasing a clutch in gear, with your foot on the brake. This issue is relatively common with E4OD's / 4R100's. I do not recall exactly where the leak is, but any competent transmission guy should be familiar with this issue.
what’s the part number for that diode?? i can’t find it
On you page it looks like the wires are hooked up to the top roll on the left hand side, the diagram online looks like the pins are on the right hand side. Can you tell me which side of the connector pin 1 is on?
That's been awhile ago and I don't immediately remember which pins are which.
What's the adjustable peice for?
I do not think these are multi later boards....
I think you're right.
The. MOV TIENE DOS PUNTOS .
SE SUPONE QUE TENGA VOLTAJES EN LOS DOS PUNTOS?
I do not have a circuit diagram, but I assume the MOV is set between GND and V+ (12 v?) and that the job of the MOV is to keep large voltage spikes from getting into this circuit board and damaging components. If you are not seeing any voltage on either side of the MOV then I could be wrong, or possibly something is keeping the V+ from getting to that point?
Sí puedes traductor en español gracias y disculpa pero queremos aprender también
Haha you did the REPAIR AND DIDN'T WORK..??
SO, YOU DIDN'T REPAIRED IT..!
COME ON...DON'T PUT UP DOME VIDEOS..LIKE THIS ONE.
He replaced the failure prone components and it didn't work. Had you watched the video further, he describes how he diagnosed and repaired the problem.
This worked for my truck after speedometer and odometer quit working simultaneously. Great video!
This worked for my truck after speedometer and odometer quit working simultaneously. Great video!
This worked for my truck after speedometer and odometer quit working simultaneously. Great video!