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.
I don't think there's a wire problem unless there's a problem right at the plug on the harness. I did have it unplugged and hanging for 2 months in the driveway while rebuilding the torque tube. I did trouble shoot this a few weeks ago when the speedometer was reading 0 the whole time. How would you got about testing the wires on the harness with an ohm meter? I may spray some electric cleaner on the plug but looked pretty clean to me. How would you check to see if the wires werent shorted or disconnected at the sensor? Only way i can think of is find them in the cabin and a continuity test from the plug to where they lead in cabin and or engine bay.
With an ohmmeter just read each pin at the VSS connector to chassis ground. You can also read across the pins. You should read something on each of the lines but they shouldn't be shorted to ground or open. You should do it with the battery disconnected. Otherwise you have to do more intrusive stuff like disconnecting the PCM harness and probing directly on the pins and finding the intermediate connectors. You should be able to follow the wires to see if any of the wiring got damaged.
Measured one I have sitting here to be 1400 ohms.
VSS controls all sorts of functions in the ecu. Not just the trans.
You should be able to get it out, just one bolt holds it in.
Since you went from no function, to something intermittent, and had it hanging for some time, checking and cleaning the connector is a good idea.
I sprayed QR electric cleaner on it last night plugged it back in now the speedometer reads 0 all the time. Im assuming its a problem at the connector or the sensor. I then tried closing the tangs on the plug as maybe they werent making good contact. Im tempted to cut the harness and use a connecter i have one here that fits the sensor perfectly. Im thinking i should atleast replace the sensor first as its 32$ before attempting to cut and resplice a new speedo sensor plug. Amazon has the sensor for 32$ ac delco and a gm pigtail for 25$ recommended for it. I have one here that just happens to be the same size. Do you think it could be a sensor problem as it is AC generated sensor where at 60mph on the hwy the car jumps from 60-40-50-60 and when braking down to 30 or even 0 the speedometer is still hung up in higher mph as if the sensor is generated voltage at a greater rate then the mph the vehicle is going. Guess when i get the funds ill try the sensor first with the stock pigtail if it doesn't work try to replace the harness plug.
EDIT: I PREVIOUSLY HAD A CODE FOR VSS LOW INPUT p0502 when i had first took the car out for a test drive after rebuilding the torque tube but doesnt show up anymore after i cleared the dic and had went for maybe 300-400 miles with no problems after clearing the code. It doesnt currently pop the code up when the speedometer was bouncing around but you would think it would. Another reason i seen the p0502 in general not the C5 dic codes list was when the engine rpm was out of range in a certain gear given mph.
Im going to purchase a new sensor ac delco when i get the funds but have found a direct plug that fits the vss maybe even heavier duty them gm's pigtail. I may run 7-10ft of wire from the plug i have and test with an ohm meter in the passenger seat to see if it changes from 1480 constant that it had tested before.
Last edited by Justin Raney; Oct 2, 2021 at 12:00 AM.
Ok i tried the vss speed sensor i got from amazon they both tested 1400s on the ohm meter. After that not working i didnt think i tugged on the terminals and noticed the one not tugging inside the plug when yanking on the wire. It easily pulled out the purple wire. After that i went ahead and fitted my delphi harness connector i have a pictured above. Its working the only complaint is that the signal wires are small 16-18 gauge or whichever while the plug connectors are 14 gauge or power wire type of stuff. The speedometer does lag lightly when backing out barely so im kinda curious as ive heard of old resistance wires or maybe too big or wiring for the voltage generated or maybe i made a poor connection. Can't believe i made that mistake it may need the pt1798 pigtail amazon recommends with the sensor with smaller wires. The harness wires that are there aren't much to work with while tucked up in there. I may end up replacing the delphi connector i used from the above picture as its wire is of thicker gauge with the 6$ ebay/amazon TX3A pigtail harness connector.
Last edited by Justin Raney; Oct 5, 2021 at 02:28 AM.
Wire gauge won't matter much in that kind of circuit since the current is pretty low. What does mater is that you have good solder connections and crimps. As you found out they can screw up sensor readings.
