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Discussion Starter · #1 ·
Hey Power Stroke Nation!! in advance thanks for any suggestions. Looking for some advice, I have a 1997 OBS 7.3 with 350k. Bought it used about 6 months ago for my son. Ran great till last week it all of a sudden stopped shifting to 1st, in drive then tested it in manual 1st. both circumstances if I rev it up to about 2500 rpm the truck will move very slowly, no grinding or irregular sounds other then the engine revving up. Reverse works perfect, looked all over the net to see if I could find help, called a friend of a friend who was a transmission shop owner, after telling him what I just explained he said to disconnect the wiring harness from the transmission, turn the truck on and manually put the truck in first. see if it works, to my surprise the truck took off like new then I Manually shifted it to second and it worked great. plugged in the harness and it went back to the same problem. So he told me the good new is it not mechanical the bad news is it electrical. First question what do you think is it mechanical or electrical? this is what I have done omhed out the wiring harness. All Good replaced the solenoid pack , new fluid, neutral shift module on drivers side, checked both fuse boxes, replaced speed solenoid on back Dif. Brother moneys tight any and all suggestion will be helpful, Although the 7.3 is a great truck I don't need it as yard art. Thanks
 

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Discussion Starter · #2 ·
Hey Power Stroke Nation!! in advance thanks for any suggestions. Looking for some advice, I have a 1997 OBS 7.3 with 350k. Bought it used about 6 months ago for my son. Ran great till last week it all of a sudden stopped shifting to 1st, in drive then tested it in manual 1st. both circumstances if I rev it up to about 2500 rpm the truck will move very slowly, no grinding or irregular sounds other then the engine revving up. Reverse works perfect, looked all over the net to see if I could find help, called a friend of a friend who was a transmission shop owner, after telling him what I just explained he said to disconnect the wiring harness from the transmission, turn the truck on and manually put the truck in first. see if it works, to my surprise the truck took off like new then I Manually shifted it to second and it worked great. plugged in the harness and it went back to the same problem. So he told me the good new is it not mechanical the bad news is it electrical. First question what do you think is it mechanical or electrical? this is what I have done omhed out the wiring harness. All Good replaced the solenoid pack , new fluid, neutral shift module on drivers side, checked both fuse boxes, replaced speed solenoid on back Dif. Brother moneys tight any and all suggestion will be helpful, Although the 7.3 is a great truck I don't need it as yard art. Thanks
sorry forgot to add 2wd automatic
 

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Former Ford Trans Engr.
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Wow! That's a lot of parts to change with no idea of what you're doing.

The problem is that the solenoid body is not getting +12v. On the connector to the transmission (on the passenger's side of the trans) there are two red wires. They must have +12v with the key on or you will have the exact symptoms that you are describing.

The problem usually is a damaged wiring harness. It could also be a problem with the PCM, but those are much less likely than a wiring problem.
 

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Discussion Starter · #4 · (Edited)
Thank you for your help Mr. Kovalsky, per your wiliness to help. I checked pin 1 and 12 on the harness that connects to the shift solenoid at the transmission with my test light, pin 1 is start hot which is red and pin 12 is Run hot which is red as well both have power. then I took my volt meter to measure what both leads are getting, with the truck running both lead have power and they both measure 13.90 volts steady.
 

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Former Ford Trans Engr.
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3,268 Posts
See if pin #3 has +12v or is grounded with the key on. With the shift handle in 2, pin 2 should be grounded.
 
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