92 F150 :Lost speedometer and odometer display
#31
08-21-2013, 06:08 AM
I wish I had a picture of one to help you out, but when you pull the cluster out you won't see much. Once you get it apart, it'll make more sense.
EDIT: I completely missed Page 2 of this thread. Sorry bout that, didn't see the pictures posted by others.
Remove the cluster from the truck, and set it face up. Take the screws out of the clear window over the gauges, and the 2 screws below it that hold the black trim on, and pull the front of it (window and trim) straight up and off.
Now you remove the gauges themselves. Start with the oil/temperature/volt/fuel gauges. These pull straight up and out. If you have a tach, pull it out too. The speedometer has to come out last, it also just pulls out.
Now that you have the speedo in your hand, turn it over and look at the back. That square PCB (circuit board) on the back is the PSOM. It comes off by removing the screws you see holding it on, and if I remember correctly it has a ribbon cable that goes to the digital mileage display.
And just for reference, the cluster is not supposed to be turned face down. I've heard two different reasons for this, one is that the digital mileage display will leak the liquid crystal stuff out, the other is that the speedo head has dampening fluid in it that will leak out. My experience is you can turn these over face down to work on them, just don't leave them like that for too long. Obviously if you have the speedo and odometer out you can turn the cluster any which way you want, but watch how you set the speedo/odo display down.
EDIT: I completely missed Page 2 of this thread. Sorry bout that, didn't see the pictures posted by others.
Remove the cluster from the truck, and set it face up. Take the screws out of the clear window over the gauges, and the 2 screws below it that hold the black trim on, and pull the front of it (window and trim) straight up and off.
Now you remove the gauges themselves. Start with the oil/temperature/volt/fuel gauges. These pull straight up and out. If you have a tach, pull it out too. The speedometer has to come out last, it also just pulls out.
Now that you have the speedo in your hand, turn it over and look at the back. That square PCB (circuit board) on the back is the PSOM. It comes off by removing the screws you see holding it on, and if I remember correctly it has a ribbon cable that goes to the digital mileage display.
And just for reference, the cluster is not supposed to be turned face down. I've heard two different reasons for this, one is that the digital mileage display will leak the liquid crystal stuff out, the other is that the speedo head has dampening fluid in it that will leak out. My experience is you can turn these over face down to work on them, just don't leave them like that for too long. Obviously if you have the speedo and odometer out you can turn the cluster any which way you want, but watch how you set the speedo/odo display down.
#33
08-21-2013, 08:37 AM
Cargo Master
Yes, I have swapped 3 EEPROMS testing to see if it can be done before I did my PSOM for my E350. So far I have not encountered any problems in my PSOM or the others I bench tested. The photos are of one of the PSOM under bench testing and also had a bad ODO display(clouded up and black smuges in it) Forgot about this I did: https://www.ford-trucks.com/forums/1...splay-fix.html
The EEPROM is the 8 DIP IC just below the blue crystal(looks like a capacitor) next to the main processor of the PSOM. I would have them use a IC socket on the new PCboard to install the EEPROM in. Makes things easyer to install/removed and less heating of the EEPROM resoldering it back in.
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