I’ve been told there are 2 VSS’s (vehicle speed sensor) on a 2000 F150 4.6 triton. they said one was for the speed-o and one was for the pcm. i know one is in the rear end… where is the other located. and could this sensor effect a certain rpm range whether in gear or not.
[b]The sensor you see in the rear end is for the ABS.
If the engine misses without the vehicle moving, then it’s not a problem with the VSS. Both VSS’s are mounted on the transmission.
Tester[/b]
Your truck has a VSS, a turbine speed sensor, and an output speed sensor.
The sensor in the rear end is the VSS it is used only for the ABS system.
The turbine speed sensor (TSS) is located just behind the bellhousing right above the PRNDL switch, the output speed sensor (OSS) is in the tailshaft housing.
The ECM uses the TSS & the OSS to control shift points in the trans. The OSS is also used for the operation of the speedometer. Failure of any of these sensor will not cause an engine running problem only a shifting problem and will usually illuminate the check engine light.
~Michael
the reason i ask about VSS’s is because my original post mentioned checking the VSS, but i forgot to mention it would o it in park… here’s my original:
i have a 2000 Ford F150 with a 4.6 Triton. engine has 125k miles on it and has been perfect all this time…seems like i just replaced my alternator prior to my problem… my problem is that when running stable between 1500 and 2000 rpm the complete ignition will shut down and the truck will buck and jerk. i can throttle through this range fine, but when stabilized it acts up. i have replaced ever electrical sensor on it. crankshaft,camshaft,throttle,MAF,all 8 plugs and all 8 coils and a brand new alternator. the shop has replaced the computer and still this truck acts up ONLY between those rpm ranges. Ford said maybe the thrust washer behind main crank bearing was worn and allowing the crank to have to much play, thus allowing crankshaft sensor to loose timing ring/wheel. the shop check crankshaft end play and said it seemed ok. they are thinking that maybe some how the crankshaft timing wheel/ring is becoming maginatized. the shop said PIP signal is kind of distorted… not as crisp as they would like…i get a p0320 code which is engine/ignition speed input circuit failure. i have put a remote start on it, but it has been on for a year before this problem started. just to make sure not crankshaft sensor i replaced it again, same problem.
P0320 - Ignition Engine Speed Input Circuit Malfunction.
The ignition engine speed sensor input signal to PCM is continuously monitored. The test fails when the signal indicates that two successive erratic profile ignition pickup (PIP) pulses have occurred.
Causes:
Loose wires/ connectors.
Arcing secondary ignition components (coil, wires and plugs)
On board transmitter (2-way radio)
When you changed the plugs and coils did you also replace the rubber boots between the coil and the plugs?
Double check the wiring to the crank sensor for damage.
Have the alternator checked for possible voltage leak.
Check all aftermarket wires and connections.
Hope it helps.
~Michael