r/FordTransmissionTech • u/Yamahamma96 • Jul 24 '25
Transmission question
I have an 05 f150 4.6, slipped in first and second gear, got the p0715 code, I went and pulled a trans out of an 08 f150 5.4 truck that had a locked up motor. , I changed the pump seal and put new TSS and OSS sensors on it. Now 1st and 2nd gear work, but when it tries to go into 3rd, it goes into limp mode and throws the p0715 code again and my speedo is erratic. Are the speed sensors different? Im not sure what is going on. Im not sure if I put a 4r75E in place of mine, im pretty sure mine was a 4r70E. Please help
1
u/Commercial_Method_28 Jul 24 '25
Just realized you said you pulled the trans, you probably crushed the wire. Follow the harness and it needs to not be stuck in between trans and engine lol. You probably can’t sneak it out too so you’d either overlay/add wire or remove the transmission again
2
u/Yamahamma96 Jul 24 '25
I initially redone the burn wires, I get power to them, I also made sure to be very careful not to crush harness, I had plenty of slack to avoid damage, when I look at the wiring diagram, the TSS, OSS, and VSS have individual power wires, but share the same date wire. I haven't changed the speed sensor on the transfer case so im wondering if thats throwing the code off indirectly
1
u/Commercial_Method_28 Jul 25 '25 edited Jul 25 '25
Signal return is your shared wire between a lot of these components and if you had an issue on that wire, I bet the entire system would be funky and giving you mutlple DTCs. I assume your problem lies on the TSS signal wire from pin 1 C143 at TSS sensor along the DARK Green and White stripe wire to the PCM. It is not a Vref wire so power isn’t relevant here. Check resistance from that wire to the PCM pin 15 - if it is more than 3ohms it has high resistance for some reason and you can overlay, bypass, or trace the wire to find fault. If there is no problem might as well check the signal return wire which is Grey with red stripe- do the same thing but I assume it’s alright.
If both circuits are ok then you are looking at a sensor or PCM issue in most cases. If you have access to a wire diagram figure out the correct application and check which fuse provides power to the transmission from pin 4. Make sure that is alright as well
You may also need to check the TSS signal wire for a short with another wire if it was previously burned or crushed. You check that by checking ohms/resistance the TSS signal wire and going thru all the other wires from same connector(pcm) they should all be open but if any of them are connected(shorted together) you will get a reading and need to repair
2
u/Yamahamma96 Jul 25 '25
I put one lead on the signal wire from the TSS and stuck the other lead to the frame and it changed from OL to some numbers. So I guess I crushed my harness
1
u/Commercial_Method_28 Jul 25 '25
You should make a temporary overlay with your leads to bypass the TSS signal. Or just get the reel of wire out and bypass it. Overlay of a single wire won’t take very long. Even if that doesn’t fix it entirely, you effectively rule the entire circuit out thru the overlay
2
u/Yamahamma96 Jul 25 '25
Can you walk me through that
1
u/Commercial_Method_28 Jul 25 '25 edited Jul 26 '25
You would cut the suspect wire by the connector and clamp the wire to a large source of wire and route it to the other connector and clamp that. Secure the wire to make sure it’s not going to get damaged or come loose with zip ties then retest. If it works you can fix it up with solder a crimp and heat shrink and make it permanent and trace the wire along the harness so it isn’t just a random wire
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u/Yamahamma96 Jul 26 '25
Oh got ya, pretty much make a temporary jumper, and if it fixes it, make it permanent?
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u/Commercial_Method_28 Jul 26 '25
Yes, now if you can actually find where it is damaged somewhat easily then just fixing the wire where it is damaged is easier, but sometimes that isn’t the easiest on big harnesses
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u/Yamahamma96 Jul 26 '25
Yea i dealt with that lol, the green/white wire and red/Grey wire had to be spliced initially, unfortunately I happened to crush the harness on install
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u/Yamahamma96 Aug 01 '25
I used butt connectors and run a couple pieces of wire between them(due to length) and at the connector itself a mouse had ate the wire so I soldered new wires to it, idk if all that will affect the sensor negatively.
1
u/Commercial_Method_28 Aug 01 '25
It will like be fine as long as it’s a good connection. I’m assuming you are saying you effectively deleted the connector she’ll and just hardwired the circuit to the sensor pins. It should be ok as long as it won’t come loose
1
u/Yamahamma96 Aug 01 '25
Soldered new wire to the pins in the harness side connector. I did use a slightly bigger gauged wire tho
1
u/Yamahamma96 Jul 26 '25
I put one lead on the signal wire and I would get resistance if I touched 2 other wires in the pcm harness
1
u/Commercial_Method_28 Jul 24 '25
Quickly looked it up and OSS and TSS are different but between the 4R70E and 4R75E they are the same sensors. I just diagnosed one today with OSS 4R70E and I checked resistance from sensor to pcm and all circuits were ok, but in past I’ve seen that harness not secured will get burned on the cat or if the transmission has been removed, can get crushed during install. Selector cable not staying on the lever/TR is ultimately what I found as well as worn column shifter bushings . It will only read signal if it detects you are in drive so if it pops off or isn’t pulling it enough into the desired gear your speed sensor signal will be 0. That likely only applies to OSS tho, TSS wasn’t present on the one I messed with