So after a recent motor swap, my speedo started acting finicky. It was fine for the first hundred miles, then it began to skip around, until it finally stopped working completely. The symptoms are exactly that of a bad electrical connection. It randomly comes back to life, and has worked about 50% of the time up until this weekend when it has stopped for good.

I pulled the VSS out yesterday to check its physical condition. I popped the top off of it to check the wiring. The grease inside surrounding the 'wheel' at the top of the shaft where the electric sensor picks up seemed dried up and 'cakey', so I scooped it out and cleaned everything up. Upon reassembly, I repacked that area with the dielectric grease I had used on the connector.

Now that everything is back together and installed with the corrosion cleaned up, the speedo is still dead as a doornail. I'm getting continuitiy to ground from the black wire, battery voltage from the black/yellow wire, and a steady 4.62v from the blue/white signal wire whether driving or sitting still. The service manual calls for 5v or more from the signal wire. I'm not sure how significant that is, but the point is it's not working. Now I'm wondering if that dielectric grease might be preventing the inductive capacity between the sensor pick-up and the wheel. So... bad sensor, or stupid move??

EDIT: VSS is from a Prelude Si, M2S4 tranny. Voltage was read from VSS pigtail while plugged up to the engine harness.

 

goto a junk yard and pick up one to see if it is a bad vss

 

I had same problem about one year ago. It turned out to be the vss unit itself. First
i found a replacement from a wrecker and then it started to fail as well. I spoke to a
auto electrician and he said that the circuitry within the unit itself fails with age due to
the harsh conditions they endure over nearly two decades. He recommended i get a new
unit from Honda, i did and no problems since. They are also quite affordable new (when i
got mine it was only $15 more than a used unit), so i would recommend first testing with a
known good used vss, and if that works, get a new one. Otherwise it is just a matter of
time until the used one fails.

 

Cool. I think I've got a couple other VSS's in my garage. They're not the right one for the tranny, but I could always swap it in to test. I'll try that this weekend hopefully.

 

Is the Check Engine light on and are you getting a code for the VSS? If so, the problem is in the VSS itself or its wiring circuit.

If the Check Engine light is not on, the problem may likely be a bad speedometer head.

 

No CEL, no codes. By speedo head are you referring to the gauge assembly?

 

You won't get a failed VSS CEL until a wire has completely broken inside. As of right now its just not reading the input from the unit in the transmission, but voltage is still going in an out from/to the ECU, so it knows its connected.

I've had this same issue before being the VSS with no CEL.

 

What car is this in? The cluster has a tendency to go bad on 91-96 hondas as well. So if a new VSS doesnt help you may need a new cluster.

 

Not really notorious on preludes, generally is the sensor.

 

Car is a 2000 Accord.

I know the issue is either faulty wiring/connection or intermittent speed sensor. When my speedo would drop out (often during hard acceleration), my launch control's rev limiter would activate because the ECU saw '0 mph' from the sensor. From what I can find in the service manual, the signal wire literally branches out to the ECU, speedo, and cruise control unit, so evidently they are all seeing the loss of signal.

I'll be going up to my garage tomorrow. I don't think I have another H23 VSS, but I might have a couple others to try out. We'll see...

QUESTION: Since all the FWD F/H series trannys are interchangeable and the VSS is only reading off the differential ring gear, can I use any F/H series VSS with the 4.266 final drive?

 

Yes . They are the same part.

 

Well, got 'home' today and dug up my stock VSS. Hooked it up to the drill, connected it to the plug and turned the ignition on. Spun it up, and nothing happened. Speedo didn't budge and ECU didn't register anything. Reconnected the original VSS and tested it out with the same result.

Still seeing battery voltage at the sensor black and black/yellow wires, continuity to ground from the black wire, and 4.68v from the blue/wht sensor wire. Not sure what in the hell is going on here. I'm almost to the point of cutting off the plug and routing my own wires from the VSS to see what I get. Any more suggestions?

 

possibly a bad ground. check all the wires. had the same issue on a bb.

 

I'm headed down today to get this thing done...

My plan is to disconnect all termination points and attempt to track down any shorts or shunts in the circuitry, double check all grounds, and rerun any wires that could be causing the issue.

 

GL, hope that fixes the problem. Electrical issues
can be f*%king annoying to sort out some times.

 

Jason, try splicing a wire from the signal near the plug straight to the speedo and see if the signal comes through.

 

Good news! It's fixed!

Continuity tested good from the sensor's connector to the gauge cluster harness, so the fault had to be in the connection. I pulled the plug apart, and the metal terminals literally fell apart in my hands. I pulled three terminals from my unused EGR plug to replace them.

Crimped and shrink-wrapped...



I almost forgot how well this car pulls at full throttle. I'm a happy man!

 

^ good to hear.