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I have a 92 F350 7.3 IDI that I have been trying to bring back to life after sitting for several years. I have replace several items including Injector pump, injectors, glow plugs, Glow plug realay (still not working correct), alternator, starter, Batteries, and Radiator so far. I can not get my Speedometer and odometer to work and my transmission shift hard and downshifts early. I have replaces the DSS or VSS on the rear end and have checked voltage and I have 0 to a little over 1.01 on plug under the hood. I have read tons of posts and am only getting confused on the troubleshooting. I am not sure what to next since my voltage is low and not at the 3.5. I have read tons of posts from SUBFORD and was looking for help troubleshooting this problem. Any help would be appreciated.
Try unplugging the RABS module behind the glove box and see if the voltage goes up.
When you say you can not get the odometer to work are talking about updating or is the LCD display blank?
Ok with RABS plugged in I get around 2.2 VAC at about 2k rpm with trans in Drive truck jacked up. With RABS unplugged I get about 4.2 VAC at about 2k RPM with trans in Drive and truck jacked up. I still do not have speedometer reading or ODOMETER reading (blank lcd). Thanks for all the help so far!
Yes it sounds like a bad PSOM. Also check the safety diode on the boards input power. I have them fall off the PSOM board. It is a surface mounted diode on the board to protect the board if someone hooks up the battery backwards or the jumper cables backwards.
You can pick up a PSOM at a salvage yard and have somebody with an EPROM burner just copy you old mileage from your old EEPROM and setup to the new boards EEPROM and change the change number back to 6.
will this fix the hard shift? how can I check to see if I am getting a good one? Is there someone I can send this to "somebody with an EPROM burner just copy you old mileage from your old EEPROM and setup to the new boards EEPROM and change the change number back to 6. " Thanks for all the help.
Yes if the replacement PSOM has a good input from the VSS wire.
Originally Posted by Metz12345
how can I check to see if I am getting a good one?
Hard to say. I take a 9volt battery with a PSOM plug on it and do the prove-out on the PSOM/speedometer head and check the display before I buy it.
Originally Posted by Metz12345
Is there someone I can send this to "somebody with an EPROM burner just copy you old mileage from your old EEPROM and setup to the new boards EEPROM and change the change number back to 6.
A lot of electronic hobbyist can do this and most know at least one with one.
There are also places you can send the PSOM to that will fix or send you back another one.
you really should park the truck.your transmission is operated electrically.it needs to know your vehicles speed via the PSOM in order to know when to shift.it's extremely hard on the trans to drive it like that.
this is why it's shifting hard......it's blind without the vehicles speed.it can't see what the vehicle is doing.
I have only drove the truck maybe a mile since getting it running, I am going to send the cluster off to get fixed, I don't need the truck running right now and am just working through all the problems.
Thanks to everyone for all the help it has been greatly appreciated!!! I will post after new cluster arrives. Thanks again!
Speedometer works fine now, transmission shift a little early now and I have instructions on how to calibrate just need some some time to work on that now thanks for all the help on this everyone. I just need to fix some broken plastic from previous owner on the back of the cluster trim piece if someone has an idea.