When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
here is the offset of the tone ring after the gearing change.
is this acceptible?
update: I took it for a drive and today it has no speedo, just bounces around 0-10mph regardless of speed and it almost wont shift at all. basically undrivable at this point, much worse than yesterday.
If the only thing you did was pull the Vss and put it back on, then I’d be checking for poor wire connection and if possible test the Vss for correct specs.
i thought that there is a test harness under hood for Vss not sure maybe?
so at this point we are thinking it is the tone-ring offset that is causing the vss to generate an unstable reading.
I sanded the tip off of the old vss to check the size of the magnet and its very small. small enough that the 1/4" ish tone ring offset could cause it not to read at higher rpms.
the diff is a yukon zip locker and its a 4.56+ so it has a different spacing from the original 4.10 carrier.
the shop that did the gears said they could move the tone ring over into alignment with the sensor as it is a press-fit.
I will try and do this myself this weekend in our shop.
if it isnt this I am almost positive the psom is dying. it could be both.
RABS Test Connector is C161. Diagram of where it is located below.
VSS Testing at that connector:
CHECK SPEED INPUT SIGNAL
NOTE: Only wiring harness end of connector is to be probed.
* Connect Rotunda Digital Volt-Ohmmeter 014-00407 or equivalent to Pin 4 (speed in ) and Pin 5 (speed in -).
* Does the voltage increase smoothly and continuously from 0 to approximately 3.5 volts as vehicle speed increases from 0 to 48 km/h (0 to 30 mph)?
OR:
* If available, a frequency counter may be connected to Pin 4 (Speed in ) and Pin 5 (Speed in -).
* Does the displayed frequency of the signal increase smoothly and continuously from 0 to approximately 667 Hz at approximately 48 km/h (30 mph)?
RABS Test Connector is C161. Diagram of where it is located below.
VSS Testing at that connector:
CHECK SPEED INPUT SIGNAL
NOTE: Only wiring harness end of connector is to be probed.
* Connect Rotunda Digital Volt-Ohmmeter 014-00407 or equivalent to Pin 4 (speed in ) and Pin 5 (speed in -).
* Does the voltage increase smoothly and continuously from 0 to approximately 3.5 volts as vehicle speed increases from 0 to 48 km/h (0 to 30 mph)?
OR:
* If available, a frequency counter may be connected to Pin 4 (Speed in ) and Pin 5 (Speed in -).
* Does the displayed frequency of the signal increase smoothly and continuously from 0 to approximately 667 Hz at approximately 48 km/h (30 mph)?
this is very helpful thank you.
does this test the analog signal from the sensor or the digital signal from the psom?
I used some alligator jumpers to connect a multimeter to the pins of what I believe was the connector and not only did I not get a reading but the rabs light came on and the speedo quit altogether.
it was the 2 pin connector attached to the main obdi diagnostic connector.
maybe my alligator clips were shorting in the connector, Im not sure, but one of them had a rubber shield on it that should have prevented it from touching the other one. I tried them in different positions, nothing.
the speedo came back and the rabs light went away after I disconnected from the diagnostic connector. still have shaky speedo above 20mph
Looks like the RABS module location is similar to the F-Series trucks (behind the glove box):
I was looking at the above wiring for the vss and rabs and the rabs uses the analog signal from the vss, not the digital signal from the psom.
so it seems highly likely that the problem is with the analog signal because if it was just a failing psom the rabs should be unaffected..
could be both as well
Rezvani's Latest Post-Apocalyptic Monster Is a Ford F-150 Raptor Underneath
Slideshow: Called the Fortress, the 850-horsepower pickup combines Raptor underpinnings with military-inspired features, survival equipment, and a starting price of $285,000.
