ok guys, i've got a 97 ford f150 with 4.2l. it's had the 4r70w tranny replaced about 50k miles ago with one from jasper transmissions. now a couple months ago i noticed the OD light started flashing. also, when i would come to a stop and go to take off the truck would stay in 3rd gear and never shift down to first. i would have to manually shift to 1st gear to take off and then shift back into Drive. so i took it to my buddy's tranny shop and had the codes read. it had a code for transmission fluid temp sensor circuit high/low and shift solenoid b fault. so i replaced the temp sensor and shift solenoid's. now it drove fine for about 2 weeks and just this morning it's started acting up again like before. but the OD light is not flashing, but the CEL came on.

here is where i get stumped... even when it starts acting up like this, it still won't shift down into first gear manually. it always goes into 2nd gear even when shift selector is in 1st. i've read that anytime there is a fault detected the PCM defaults to 2nd gear.... but wouldn't you be able to do a manual 1st gear? so other than tracing wires (which i will be doing today) and replacing PCM, i am stumped for now. i really need this truck to haul wood with this winter and this couldn't have happened at a better time!!!!

i'm a pretty decent diesel mechanic, i work on big rigs. i've rebuilt a couple of automatic tranny's... so i'm up for the challenge of this one. i will NEVER let a machine beat me!

guess i just need to see if anyone else has had experience with this or someone that can point me in the right direction. talked to a ford mechanic at a local dealership and he said he could count on 1 hand how many PCM's he's changed on these trucks... but i live in a really small town.

all help is greatly appreciated!! thanks!

 

Read the codes.

 

sorry, i guess i left that part out... same code as before, shift solenoid b failure

 

So what was the verdict if any?

 

well.... i've been real busy these past few days so i haven't gotten a chance to get it in the shop. but the CEL went off today and it's back to shifting great. just waiting for things to slow down around here so i can get a chance to work on it. going to check all my wires and connections. i'm gonna pull every wire loom off if i have to. i really really hate intermitent problems like these.

 

well, the verdict is in.... i think. i checked the wiring today and found that the harness had fallen down and was getting on the exhaust pipe for EGR. looks like it was shorting out at times... had a bad spot on one of the wires, but i didn't check the color of the wire to see which one it was. i think it was black/red maybe. i just fixed it up and re-routed the harness.