I hope someone can offer me an idea of what the deal is here.

I installed a remanufactured 2003 4R70W trans into my 1997 F150 4x4 with 4.6.

I made the wire harness modification and it is good. The problem I have is the OSS sensor is reading some, as the tech called them, crazy readings.
He said that he got a reading of over 5000 rpm, I'm not sure how fast he was driving at the time. But he said with that rpm the truck should be going near 200mph.

Because of this out of wack reading the truck wouldn't shift right. But with the sensor unpluged it does. Of course the Eng Check light is on because it's unpluged.

3 OSS sensors were tried, and still the high reading.

So my questions are, is there a difference in the Tone Ring between '97 and 2003 that could account for this high reading?

If so is there any work around for this? (Such as reprograming the computer so it calculates the correct reading)

What proplems if any, other than the Check Eng Light constantly being on, could running with the OSS unpluged cause?

Help,
Doug

 

Does your truck use an original OSS or a VSS?
Is the replacement trans setup the same as the 97 ?
Seems the output shaft has to many signal points for the sensor and the PCM program version is not set for that high a data rate.
Look at the output shaft number of signal points of both transmissions.
They must be the same.
Just some thoughts without fully knowing about all the differences between the transmission years and options per an application..
I can fully understand why the PCM and transmission won't be happy.
Good luck.

 

OK, a little additional information, based on Bluegrasses questions.

According to the wiring diagrams the truck has both an OSS and VSS sensor. (Output Shaft Speed and Vehicle Speed Sensors.)

I’d imagine that the VSS is the one on the transfer case with the gear in it.

The one on left rear of the transmission was the one that seems to be reading wrong. With it plugged in the reading is high and it wants to shift from 2nd to 4th. With it unplugged the Check Eng light is on but it shifts through the gears and is drivable.

On the replacement trans there is another sensor located directly above the MLPS (Digital Transmission Range Sensor), that came with a cap over the plug. I’ve now idea what it is for; I assumed it was used for testing.

If anyone has wiring diagrams for a 2003 Trans Wiring Harness that might help me figure things out. Also if anyone knows if the tone ring had a different number of teeth than the 97.

Doug

 

On an or 4r70w for 2002,
The OSS DB/YE goes to PCM pin 84.
The other side BN/LG goes to the PCM pin 91 as well at the DTR pin 2 on a GY/RD lead.
OSS adds control to the shift skeds, the TCC lockup and EPC internal control pressures.
Might be the same as 03.

 

I appreciate the information, but it is really of no help.

The 2003 trans is installed in a 1997 and running on the '97 harness and PCM etc. Mods were done on the harnes so the trans connector and OSS connector could connect to the 2003 transmission and OSS sensor.

The problem is that the signal from the OSS sensor is causing the PCM to think the output rpm is around 5000 rpm at cruise speed.

Other OSS's have been tried so we know the sensor isn't the problem. Best guess is that there are a different number of teeth on the tone ring on the 2003 than the original 1997. So that the signal from the OSS is correct, but the PCM is interpreting it wrong because it is expecting a lower signal rate than it is getting.

Unfortunatly the '97 was already torn down and scraped so I can't check it's tone ring.

Can anyone tell me how many teeth are on the '97 tone ring and also the 2003 tone ring?

Doug

 

Bump,

Can anyone offer me any more help with this.

Doug