Rebuilt 4R70W ... Output Shaft Speed Sensor Issue?

[Meteorite]

I have two 2003 Marauders with failed 4R70W transmissions. I already had the transmission out of the first car and recently got it rebuilt. In the interim, the second Marauder's transmission failed, so I swapped the newly rebuilt transmission into the second car.

I wanted to run it up through the gears with the vehicle on the jackstands. Reverse seemed normal. But in "D", I noticed that it didn't want to shift out of 1st Gear. Moreover, the speedometer isn't reading right. At an engine speed of 2500 RPM, the speedometer read 10 mph. I confirmed that with a scanner (which said about 9 mph at the same engine speed). Doing the math for first gear, I think the wheel speed should equate to more like 17 or 18 mph.

I'm thinking that the normal shift schedule is prohibiting the upshifts because one of the inputs to the table is vehicle speed, and I believe I'm feeding in a faulty vehicle speed.

I tried changing the Output Speed Sensor (OSS) from my other car into the problem car, but it made no difference. I also tried swapping in the TRS from the first car; no help.

No trouble codes are present at all.

I put a piece of tape on one of the rear wheels, and let the car idle in M1 position. This verified that the wheels were moving at an appropriate speed given the engine speed at idle.

Anyone have any ideas what might cause the speedometer to be reading wrong? I have a new OSS on order from the dealership, but I'm not super hopeful, since I've already swapped in one that seems to have been working.

[Blown3.8]

It sounds like the reluctor for the OSS has the wrong amount of holes. You can get a tune to fix the issue. Are the calibration codes different between the 2 vehicles?

There are either 6 or 24 teeth. You could probably remove the sensor mark one of the teeth and count them on both trans'.

[Meteorite]

Yes! This makes perfect sense.

So, here is the timeline:

1. A few years back, I drop off this current Marauder (the one I'm working on) for a trans rebuild at my tuner's shop. Tuner removes the trans from the car and sends it out to his rebuilder.
2. Trans rebuilder uses 4R75 (24-lug) Output Ring Gear in place of the existing 4R70W 6-hole Output Ring.
3. Tuner re-installs the trans, notices the speedo is off by a factor of 4, and fixes it in the tune.
4. That trans fails, so I have a 4R70W (6-hole reluctor ring) from my other Marauder rebuilt and install it in the current car, which is expecting a 24-tooth signal.
5. Speed reads 4 times too low.

Thanks! I'm hoping to get this fixed in the tune and be good to go. I will updated the thread if this fixes it.



It sounds like the reluctor for the OSS has the wrong amount of holes. You can get a tune to fix the issue. Are the calibration codes different between the 2 vehicles?

There are either 6 or 24 teeth. You could probably remove the sensor mark one of the teeth and count them on both trans'.

[martyo]

It sounds like the reluctor for the OSS has the wrong amount of holes. You can get a tune to fix the issue. Are the calibration codes different between the 2 vehicles?

There are either 6 or 24 teeth. You could probably remove the sensor mark one of the teeth and count them on both trans'.


This is correct.

We can adjust this with a tune.

[justbob]

Good advice here! Same thing here kind of. While my speedo was off by double or more, mine at least shifted thanks to having a manny tranny!

Easy adjustment on the tune!


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[hotford]

Yup, ford changed them up in 2004, ran into this same issue on my Mach 1, easy fix in the tune.

2003 has 24

2004 has 6

[Meteorite]

I had my tuner change the parameter for me, and all is well now! Thanks!



Yup, ford changed them up in 2004, ran into this same issue on my Mach 1, easy fix in the tune.

2003 has 24

2004 has 6

Actually, it's the other way around. 4R75 has 24 lugs; 4R70 has 6 holes.

[hotford]

^^^Correct......I knew it was one or the other, my car wouldn't shift 3 and speedo was way out, took me a bit to figure it out...….^^^^^^^^^

[Meteorite]

So, now I've had a second transmission rebuilt for my other supercharged Marauder, and after installing it, I'm getting a DIFFERENT speedo issue.

This time (running it on jack stands) the speedometer is smooth up until 20 mph, but as soon as the trans makes the 1-2 shift, the speedometer needle starts fluctuating wildly, like between
10 mph and 40 mph. I can eventually get the 2-3 shift (and 3-4), but they are all pretty harsh, as if made on full line pressure. And it can't be good to feed a bogus vehicle speed into
the PCM, because it'll mess with the shift schedule.

So, I put in a new Output Speed Sensor, but the condition persists.

If I get into O/D and hold the pedal steady or if I reduce or increase speed slowly, the speedo needle is fine, but if I back out and then push the O/D Cancel button to force a 4-3 shift,
it starts swinging wildly again.

Any clue what could be causing this?

I did take it out on the street, and the behavior is similar to how it is on the jack stands. I can get Reverse and all 4 Forward gears, but the speedo is wacked after every shift.

[decipha]

unplug the alternator and see if that changes anything

[Meteorite]

unplug the alternator and see if that changes anything

Thank you for this idea; I'm intrigued! Why would the alternator affect this?

I will tell you this: I am getting a P1246 code (Alternator Load Input Failed).