after 2 other posts with no insite this is my last attempt. PLEASE someone give me a clue. 99 f150 v6 auto 2wd. P0722 oss(vss) insufficeient feed is the code thrown. the truck is having shifting problems, no speedo, after 1-2 shift is missed odometer goes blank and check engine and abs light comes on. does shift under LIGHT driving or hard driving but not normal driving. both vss and oss have been replaced. wires have bene checked, giggled wiggled, no blown fuses, etc... anyone have ANY idea of where else to look. thanks for any help

 

I would check for an AC signal at the PCM pins 33 and 58, with the rear off the ground on jack stands and turning in gear. This signal is needed for all the reasons your having a problem with.
P722 code is OSS failed to provide the PCM with inital and ongoing output shaft speed signal.
I believe the dash gets this signal on a secondary basis.

 

am i checking the ac BETWEEN the 2 pins, as in ground lead on one and hot lead on the other? or do i need to COMPARE the ac between the two as in lead one on one pin, lead 2 on the other, and ground at chassis ground? and where can i find a pin out of the ecm? dont wanna burn anything up i dont have to

 

Your looking at the output of the sensor as it turns so the wiring to the measue point at the PCM, is proven out. It is not referenced to ground.
If you don't see the signal, it's the problem.
Harness is either open, crossed or grounded.

Another way is to remove a battery cable, remove the connector off the PCM.
there should be markings on the connector showing the pin counts.
Have someone help by turning the speed sensor while you measure at the pins of the connector.
You can also test for cross, and grounds from either end.
To check for an open, shunt the connector at the sensor location and measue to see that cross at the other end with the meter set to measure low resistance values.

 

Have you actually followed the factory diagnostic procedure yet for your specific fault code?

If not, you're wasting a lot of your money and time....

Steve

 

no, i do not have a copy of their diagnostic outline, nor do i konw where to find one, the internet isnt what it used to be when u search stuff. all i find is info for ford tarus and toyota and thats not helping so im shure im going about this wrong. if u could give me info on where to look i would be greatful thou, it would make this alot easier.i replaced the two sensors jsut to make sure that wasnt it. they were 18 bucks for the pair so it wasnt a great loss.im going to put my labscope on it and see what if any signal i get from the two sensors. least ill konw if the circuit is working. if it is then im sure either the ecm took a dump or something else is awry that didnt pop any codes either standard or extended. any help is 1 step forward, thanks for the suggestions.

 

Send me an email i will send you the list from the manual.



Thanks
Josh

 

....umm, not sure where you got those pin #s, but my EVTM shows both as "NOT USED".

The correct pins should be pin 84 (OSS signal) and pin 91 (signal return). The signal should be a clean AC waveform that varies in frequency as the output shaft of the tranny varies rotational speed. On the 99, this signal goes only to the PCM, it does not go directly to the cluster. The cluster receives speed data for display via the SCP bus from the PCM.

You can perform a quick circuit check of the wiring and sensor circuit by checking for a circuit resistance of 1.38Kohms +/- 600 ohms. If you measure an open circuit, either the sensor is open, the wiring harness is open, or you have a a faulty connection. If your resistance reading is good and solid but the AC signal is missing, I'd be looking for a mechanical problem either on the business end of the sensor or at the exciter ring inside the tranny.

Steve

 

from what i am told by a local tranny shop the truck is a midyear split, making it a 99 1/2 if that makes any differnece. the rain has kept me from getting under it so no update yet but thanks to all for the help.

 

The pin numbers I gave came from a pin-out drawing I have that was supposed to be for 95 up PCM, so could be still be incorrect by 99 or 2000 model year.
I would think that you will see the problem either in the harness, connector or the sensor output.
The PCM needs the signal to process logic functions, then the dash get it's feed.